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Chapter 26. Load balancing with MetalLB

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26.1. About MetalLB and the MetalLB Operator

As a cluster administrator, you can add the MetalLB Operator to your cluster so that when a service of type LoadBalancer is added to the cluster, MetalLB can add an external IP address for the service. The external IP address is added to the host network for your cluster.

You can configure MetalLB so that the IP address is advertised with layer 2 protocols. With layer 2, MetalLB provides a fault-tolerant external IP address.

You can configure MetalLB so that the IP address is advertised with the BGP protocol. With BGP, MetalLB provides fault-tolerance for the external IP address and load balancing.

MetalLB supports providing layer 2 for some IP addresses and BGP for other IP addresses.

26.1.1. When to use MetalLB

Using MetalLB is valuable when you have a bare-metal cluster, or an infrastructure that is like bare metal, and you want fault-tolerant access to an application through an external IP address.

You must configure your networking infrastructure to ensure that network traffic for the external IP address is routed from clients to the host network for the cluster.

After deploying MetalLB with the MetalLB Operator, when you add a service of type LoadBalancer, MetalLB provides a platform-native load balancer.

MetalLB operating in layer2 mode provides support for failover by utilizing a mechanism similar to IP failover. However, instead of relying on the virtual router redundancy protocol (VRRP) and keepalived, MetalLB leverages a gossip-based protocol to identify instances of node failure. When a failover is detected, another node assumes the role of the leader node, and a gratuitous ARP message is dispatched to broadcast this change.

MetalLB operating in layer3 or border gateway protocol (BGP) mode delegates failure detection to the network. The BGP router or routers that the OpenShift Container Platform nodes have established a connection with will identify any node failure and terminate the routes to that node.

Using MetalLB instead of IP failover is preferable for ensuring high availability of pods and services.

26.1.2. MetalLB Operator custom resources

The MetalLB Operator monitors its own namespace for the following custom resources:

MetalLB
When you add a MetalLB custom resource to the cluster, the MetalLB Operator deploys MetalLB on the cluster. The Operator only supports a single instance of the custom resource. If the instance is deleted, the Operator removes MetalLB from the cluster.
AddressPool
MetalLB requires one or more pools of IP addresses that it can assign to a service when you add a service of type LoadBalancer. When you add an AddressPool custom resource to the cluster, the MetalLB Operator configures MetalLB so that it can assign IP addresses from the pool. An address pool includes a list of IP addresses. The list can be a single IP address that is set using a range, such as 1.1.1.1-1.1.1.1, a range specified in CIDR notation, a range specified as a starting and ending address separated by a hyphen, or a combination of the three. An address pool requires a name. The documentation uses names like doc-example, doc-example-reserved, and doc-example-ipv6. An address pool specifies whether MetalLB can automatically assign IP addresses from the pool or whether the IP addresses are reserved for services that explicitly specify the pool by name. An address pool specifies whether MetalLB uses layer 2 protocols to advertise the IP addresses, or whether the BGP protocol is used.
BGPPeer
The BGP peer custom resource identifies the BGP router for MetalLB to communicate with, the AS number of the router, the AS number for MetalLB, and customizations for route advertisement. MetalLB advertises the routes for service load-balancer IP addresses to one or more BGP peers. The service load-balancer IP addresses are specified with AddressPool custom resources that set the protocol field to bgp.
BFDProfile
The BFD profile custom resource configures Bidirectional Forwarding Detection (BFD) for a BGP peer. BFD provides faster path failure detection than BGP alone provides.

After you add the MetalLB custom resource to the cluster and the Operator deploys MetalLB, the MetalLB software components, controller and speaker, begin running.

The Operator includes validating webhooks for the AddressPool and BGPPeer custom resources. The webhook for the address pool custom resource performs the following checks:

  • Address pool names must be unique.
  • IP address ranges do not overlap with an existing address pool.
  • If the address pool includes a bgpAdvertisement field, the protocol field must be set to bgp.

The webhook for the BGP peer custom resource performs the following checks:

  • If the BGP peer name matches an existing peer, the IP address for the peer must be unique.
  • If the keepaliveTime field is specified, the holdTime field must be specified and the keep-alive duration must be less than the hold time.
  • The myASN field must be the same for all BGP peers.

26.1.3. MetalLB software components

When you install the MetalLB Operator, the metallb-operator-controller-manager deployment starts a pod. The pod is the implementation of the Operator. The pod monitors for changes to the MetalLB custom resource and AddressPool custom resources.

When the Operator starts an instance of MetalLB, it starts a controller deployment and a speaker daemon set.

controller

The Operator starts the deployment and a single pod. When you add a service of type LoadBalancer, Kubernetes uses the controller to allocate an IP address from an address pool. In case of a service failure, verify you have the following entry in your controller pod logs:

Example output

"event":"ipAllocated","ip":"172.22.0.201","msg":"IP address assigned by controller

speaker

The Operator starts a daemon set for speaker pods. By default, a pod is started on each node in your cluster. You can limit the pods to specific nodes by specifying a node selector in the MetalLB custom resource when you start MetalLB. If the controller allocated the IP address to the service and service is still unavailable, read the speaker pod logs. If the speaker pod is unavailable, run the oc describe pod -n command.

For layer 2 mode, after the controller allocates an IP address for the service, the speaker pods use an algorithm to determine which speaker pod on which node will announce the load balancer IP address. The algorithm involves hashing the node name and the load balancer IP address. For more information, see "MetalLB and external traffic policy". The speaker uses Address Resolution Protocol (ARP) to announce IPv4 addresses and Neighbor Discovery Protocol (NDP) to announce IPv6 addresses.

For BGP mode, after the controller allocates an IP address for the service, each speaker pod advertises the load balancer IP address with its BGP peers. You can configure which nodes start BGP sessions with BGP peers.

Requests for the load balancer IP address are routed to the node with the speaker that announces the IP address. After the node receives the packets, the service proxy routes the packets to an endpoint for the service. The endpoint can be on the same node in the optimal case, or it can be on another node. The service proxy chooses an endpoint each time a connection is established.

26.1.4. MetalLB concepts for layer 2 mode

In layer 2 mode, the speaker pod on one node announces the external IP address for a service to the host network. From a network perspective, the node appears to have multiple IP addresses assigned to a network interface.

Note

In layer 2 mode, MetalLB relies on ARP and NDP. These protocols implement local address resolution within a specific subnet. In this context, the client must be able to reach the VIP assigned by MetalLB that exists on the same subnet as the nodes announcing the service in order for MetalLB to work.

The speaker pod responds to ARP requests for IPv4 services and NDP requests for IPv6.

In layer 2 mode, all traffic for a service IP address is routed through one node. After traffic enters the node, the service proxy for the CNI network provider distributes the traffic to all the pods for the service.

Because all traffic for a service enters through a single node in layer 2 mode, in a strict sense, MetalLB does not implement a load balancer for layer 2. Rather, MetalLB implements a failover mechanism for layer 2 so that when a speaker pod becomes unavailable, a speaker pod on a different node can announce the service IP address.

When a node becomes unavailable, failover is automatic. The speaker pods on the other nodes detect that a node is unavailable and a new speaker pod and node take ownership of the service IP address from the failed node.

Conceptual diagram for MetalLB and layer 2 mode

The preceding graphic shows the following concepts related to MetalLB:

  • An application is available through a service that has a cluster IP on the 172.130.0.0/16 subnet. That IP address is accessible from inside the cluster. The service also has an external IP address that MetalLB assigned to the service, 192.168.100.200.
  • Nodes 1 and 3 have a pod for the application.
  • The speaker daemon set runs a pod on each node. The MetalLB Operator starts these pods.
  • Each speaker pod is a host-networked pod. The IP address for the pod is identical to the IP address for the node on the host network.
  • The speaker pod on node 1 uses ARP to announce the external IP address for the service, 192.168.100.200. The speaker pod that announces the external IP address must be on the same node as an endpoint for the service and the endpoint must be in the Ready condition.
  • Client traffic is routed to the host network and connects to the 192.168.100.200 IP address. After traffic enters the node, the service proxy sends the traffic to the application pod on the same node or another node according to the external traffic policy that you set for the service.

    • If the external traffic policy for the service is set to cluster, the node that advertises the 192.168.100.200 load balancer IP address is selected from the nodes where a speaker pod is running. Only that node can receive traffic for the service.
    • If the external traffic policy for the service is set to local, the node that announces the 192.168.100.200 load balancer IP address is selected from the nodes where a speaker pod is running and at least an endpoint of the service. Only that node can receive traffic for the service. In the preceding graphic, either node 1 or 3 would advertise 192.168.100.200.
  • If node 1 becomes unavailable, the external IP address fails over to another node. On another node that has an instance of the application pod and service endpoint, the speaker pod begins to announce the external IP address, 192.168.100.200 and the new node receives the client traffic. In the diagram, the only candidate is node 3.

26.1.5. MetalLB concepts for BGP mode

In BGP mode, each speaker pod advertises the load balancer IP address for a service to each BGP peer. BGP peers are commonly network routers that are configured to use the BGP protocol. When a router receives traffic for the load balancer IP address, the router picks one of the nodes with a speaker pod that advertised the IP address. The router sends the traffic to that node. After traffic enters the node, the service proxy for the CNI network provider distributes the traffic to all the pods for the service.

The directly-connected router on the same layer 2 network segment as the cluster nodes can be configured as a BGP peer. If the directly-connected router is not configured as a BGP peer, you need to configure your network so that packets for load balancer IP addresses are routed between the BGP peers and the cluster nodes that run the speaker pods.

Each time a router receives new traffic for the load balancer IP address, it creates a new connection to a node. Each router manufacturer has an implementation-specific algorithm for choosing which node to initiate the connection with. However, the algorithms commonly are designed to distribute traffic across the available nodes for the purpose of balancing the network load.

If a node becomes unavailable, the router initiates a new connection with another node that has a speaker pod that advertises the load balancer IP address.

Figure 26.1. MetalLB topology diagram for BGP mode

Speaker pods on host network 10.0.1.0/24 use BGP to advertise the load balancer IP address, 203.0.113.200, to a router.

The preceding graphic shows the following concepts related to MetalLB:

  • An application is available through a service that has an IPv4 cluster IP on the 172.130.0.0/16 subnet. That IP address is accessible from inside the cluster. The service also has an external IP address that MetalLB assigned to the service, 203.0.113.200.
  • Nodes 2 and 3 have a pod for the application.
  • The speaker daemon set runs a pod on each node. The MetalLB Operator starts these pods. You can configure MetalLB to specify which nodes run the speaker pods.
  • Each speaker pod is a host-networked pod. The IP address for the pod is identical to the IP address for the node on the host network.
  • Each speaker pod starts a BGP session with all BGP peers and advertises the load balancer IP addresses or aggregated routes to the BGP peers. The speaker pods advertise that they are part of Autonomous System 65010. The diagram shows a router, R1, as a BGP peer within the same Autonomous System. However, you can configure MetalLB to start BGP sessions with peers that belong to other Autonomous Systems.
  • All the nodes with a speaker pod that advertises the load balancer IP address can receive traffic for the service.

    • If the external traffic policy for the service is set to cluster, all the nodes where a speaker pod is running advertise the 203.0.113.200 load balancer IP address and all the nodes with a speaker pod can receive traffic for the service. The host prefix is advertised to the router peer only if the external traffic policy is set to cluster.
    • If the external traffic policy for the service is set to local, then all the nodes where a speaker pod is running and at least an endpoint of the service is running can advertise the 203.0.113.200 load balancer IP address. Only those nodes can receive traffic for the service. In the preceding graphic, nodes 2 and 3 would advertise 203.0.113.200.
  • You can configure MetalLB to control which speaker pods start BGP sessions with specific BGP peers by specifying a node selector when you add a BGP peer custom resource.
  • Any routers, such as R1, that are configured to use BGP can be set as BGP peers.
  • Client traffic is routed to one of the nodes on the host network. After traffic enters the node, the service proxy sends the traffic to the application pod on the same node or another node according to the external traffic policy that you set for the service.
  • If a node becomes unavailable, the router detects the failure and initiates a new connection with another node. You can configure MetalLB to use a Bidirectional Forwarding Detection (BFD) profile for BGP peers. BFD provides faster link failure detection so that routers can initiate new connections earlier than without BFD.

26.1.6. MetalLB and external traffic policy

With layer 2 mode, one node in your cluster receives all the traffic for the service IP address. With BGP mode, a router on the host network opens a connection to one of the nodes in the cluster for a new client connection. How your cluster handles the traffic after it enters the node is affected by the external traffic policy.

cluster

This is the default value for spec.externalTrafficPolicy.

With the cluster traffic policy, after the node receives the traffic, the service proxy distributes the traffic to all the pods in your service. This policy provides uniform traffic distribution across the pods, but it obscures the client IP address and it can appear to the application in your pods that the traffic originates from the node rather than the client.

local

With the local traffic policy, after the node receives the traffic, the service proxy only sends traffic to the pods on the same node. For example, if the speaker pod on node A announces the external service IP, then all traffic is sent to node A. After the traffic enters node A, the service proxy only sends traffic to pods for the service that are also on node A. Pods for the service that are on additional nodes do not receive any traffic from node A. Pods for the service on additional nodes act as replicas in case failover is needed.

This policy does not affect the client IP address. Application pods can determine the client IP address from the incoming connections.

26.1.7. Limitations and restrictions

26.1.7.1. Infrastructure considerations for MetalLB

MetalLB is primarily useful for on-premise, bare metal installations because these installations do not include a native load-balancer capability. In addition to bare metal installations, installations of OpenShift Container Platform on some infrastructures might not include a native load-balancer capability. For example, the following infrastructures can benefit from adding the MetalLB Operator:

  • Bare metal
  • VMware vSphere

MetalLB Operator and MetalLB are supported with the OpenShift SDN and OVN-Kubernetes network providers.

26.1.7.2. Limitations for layer 2 mode

26.1.7.2.1. Single-node bottleneck

MetalLB routes all traffic for a service through a single node, the node can become a bottleneck and limit performance.

Layer 2 mode limits the ingress bandwidth for your service to the bandwidth of a single node. This is a fundamental limitation of using ARP and NDP to direct traffic.

26.1.7.2.2. Slow failover performance

Failover between nodes depends on cooperation from the clients. When a failover occurs, MetalLB sends gratuitous ARP packets to notify clients that the MAC address associated with the service IP has changed.

Most client operating systems handle gratuitous ARP packets correctly and update their neighbor caches promptly. When clients update their caches quickly, failover completes within a few seconds. Clients typically fail over to a new node within 10 seconds. However, some client operating systems either do not handle gratuitous ARP packets at all or have outdated implementations that delay the cache update.

Recent versions of common operating systems such as Windows, macOS, and Linux implement layer 2 failover correctly. Issues with slow failover are not expected except for older and less common client operating systems.

To minimize the impact from a planned failover on outdated clients, keep the old node running for a few minutes after flipping leadership. The old node can continue to forward traffic for outdated clients until their caches refresh.

During an unplanned failover, the service IPs are unreachable until the outdated clients refresh their cache entries.

26.1.7.3. Limitations for BGP mode

26.1.7.3.1. Node failure can break all active connections

MetalLB shares a limitation that is common to BGP-based load balancing. When a BGP session terminates, such as when a node fails or when a speaker pod restarts, the session termination might result in resetting all active connections. End users can experience a Connection reset by peer message.

The consequence of a terminated BGP session is implementation-specific for each router manufacturer. However, you can anticipate that a change in the number of speaker pods affects the number of BGP sessions and that active connections with BGP peers will break.

To avoid or reduce the likelihood of a service interruption, you can specify a node selector when you add a BGP peer. By limiting the number of nodes that start BGP sessions, a fault on a node that does not have a BGP session has no affect on connections to the service.

26.1.7.3.2. Communities are specified as 16-bit values

Communities are specified as part of an address pool custom resource and are specified as 16-bit values separated by a colon. For example, to specify that load balancer IP addresses are advertised with the well-known NO_ADVERTISE community attribute, use notation like the following:

apiVersion: metallb.io/v1beta1
kind: AddressPool
metadata:
  name: doc-example-no-advertise
  namespace: metallb-system
spec:
  protocol: bgp
  addresses:
    - 192.168.1.100-192.168.1.255
  bgpAdvertisements:
  - communities:
    - 65535:65282

The limitation that communities are only specified as 16-bit values is a difference with the community-supported implementation of MetalLB that supports a bgp-communities field and readable names for BGP communities.

26.1.7.3.3. Support for a single ASN and a single router ID only

When you add a BGP peer custom resource, you specify the spec.myASN field to identify the Autonomous System Number (ASN) that MetalLB belongs to. OpenShift Container Platform uses an implementation of BGP with MetalLB that requires MetalLB to belong to a single ASN. If you attempt to add a BGP peer and specify a different value for spec.myASN than an existing BGP peer custom resource, you receive an error.

Similarly, when you add a BGP peer custom resource, the spec.routerID field is optional. If you specify a value for this field, you must specify the same value for all other BGP peer custom resources that you add.

The limitation to support a single ASN and single router ID is a difference with the community-supported implementation of MetalLB.

26.1.8. Additional resources

26.2. Installing the MetalLB Operator

As a cluster administrator, you can add the MetallB Operator so that the Operator can manage the lifecycle for an instance of MetalLB on your cluster.

The installation procedures use the metallb-system namespace. You can install the Operator and configure custom resources in a different namespace. The Operator starts MetalLB in the same namespace that the Operator is installed in.

MetalLB and IP failover are incompatible. If you configured IP failover for your cluster, perform the steps to remove IP failover before you install the Operator.

26.2.1. Installing the MetalLB Operator from the OperatorHub using the web console

As a cluster administrator, you can install the MetalLB Operator by using the OpenShift Container Platform web console.

Procedure

  1. Log in to the OpenShift Container Platform web console.
  2. Optional: Create the required namespace for the MetalLB Operator:

    Note

    You can choose to create the namespace at this stage or you can create it when you start the MetalLB Operator install. From the Installed Namespace list you can create the project.

    1. Navigate to Administration Namespaces and click Create Namespace.
    2. Enter metallb-system in the Name field, and click Create.
  3. Install the MetalLB Operator:

    1. In the OpenShift Container Platform web console, click Operators OperatorHub.
    2. Type metallb into the Filter by keyword field to find the MetalLB Operator, and then click Install.

      You can also filter options by Infrastructure Features. For example, select Disconnected if you want to see Operators that work in disconnected environments, also known as restricted network environments.

    3. On the Install Operator page, select a specific namespace on the cluster. Select the namespace created in the earlier section or choose to create the metallb-system project, and then click Install.

Verification

To verify that the MetalLB Operator installed successfully:

  1. Navigate to the Operators Installed Operators page.
  2. Ensure that MetalLB Operator is listed in the metallb-system project with a Status of Succeeded.

    Note

    During installation, an Operator might display a Failed status. If the installation later succeeds with an Succeeded message, you can ignore the Failed message.

  3. If the Operator installation does not succeed, you can troubleshoot further:

    1. Navigate to the Operators Installed Operators page and inspect the Operator Subscriptions and Install Plans tabs for any failure or errors under Status.
    2. Navigate to the Workloads Pods page and check the logs for pods in the metallb-system project.

26.2.2. Installing from OperatorHub using the CLI

Instead of using the OpenShift Container Platform web console, you can install an Operator from OperatorHub using the CLI. Use the oc command to create or update a Subscription object.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.

Procedure

  1. Confirm that the MetalLB Operator is available:

    $ oc get packagemanifests -n openshift-marketplace metallb-operator

    Example output

    NAME               CATALOG                AGE
    metallb-operator   Red Hat Operators      9h

  2. Create the metallb-system namespace:

    $ cat << EOF | oc apply -f -
    apiVersion: v1
    kind: Namespace
    metadata:
      name: metallb-system
    EOF
  3. Optional: To ensure BGP and BFD metrics appear in Prometheus, you can label the namespace as in the following command:

    $ oc label ns metallb-system "openshift.io/cluster-monitoring=true"
  4. Create an Operator group custom resource in the namespace:

    $ cat << EOF | oc apply -f -
    apiVersion: operators.coreos.com/v1
    kind: OperatorGroup
    metadata:
      name: metallb-operator
      namespace: metallb-system
    spec:
      targetNamespaces:
      - metallb-system
    EOF
  5. Confirm the Operator group is installed in the namespace:

    $ oc get operatorgroup -n metallb-system

    Example output

    NAME               AGE
    metallb-operator   14m

  6. Subscribe to the MetalLB Operator.

    1. Run the following command to get the OpenShift Container Platform major and minor version. You use the values to set the channel value in the next step.

      $ OC_VERSION=$(oc version -o yaml | grep openshiftVersion | \
          grep -o '[0-9]*[.][0-9]*' | head -1)
    2. To create a subscription custom resource for the Operator, enter the following command:

      $ cat << EOF| oc apply -f -
      apiVersion: operators.coreos.com/v1alpha1
      kind: Subscription
      metadata:
        name: metallb-operator-sub
        namespace: metallb-system
      spec:
        channel: "${OC_VERSION}"
        name: metallb-operator
        source: redhat-operators
        sourceNamespace: openshift-marketplace
      EOF
  7. Confirm the install plan is in the namespace:

    $ oc get installplan -n metallb-system

    Example output

    NAME            CSV                                                 APPROVAL    APPROVED
    install-wzg94   metallb-operator.4.10.0-nnnnnnnnnnnn   Automatic   true

  8. To verify that the Operator is installed, enter the following command:

    $ oc get clusterserviceversion -n metallb-system \
      -o custom-columns=Name:.metadata.name,Phase:.status.phase

    Example output

    Name                                                Phase
    metallb-operator.4.10.0-nnnnnnnnnnnn   Succeeded

26.2.3. Starting MetalLB on your cluster

After you install the Operator, you need to configure a single instance of a MetalLB custom resource. After you configure the custom resource, the Operator starts MetalLB on your cluster.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Install the MetalLB Operator.

Procedure

  1. Create a single instance of a MetalLB custom resource:

    $ cat << EOF | oc apply -f -
    apiVersion: metallb.io/v1beta1
    kind: MetalLB
    metadata:
      name: metallb
      namespace: metallb-system
    EOF

Verification

Confirm that the deployment for the MetalLB controller and the daemon set for the MetalLB speaker are running.

  1. Check that the deployment for the controller is running:

    $ oc get deployment -n metallb-system controller

    Example output

    NAME         READY   UP-TO-DATE   AVAILABLE   AGE
    controller   1/1     1            1           11m

  2. Check that the daemon set for the speaker is running:

    $ oc get daemonset -n metallb-system speaker

    Example output

    NAME      DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR            AGE
    speaker   6         6         6       6            6           kubernetes.io/os=linux   18m

    The example output indicates 6 speaker pods. The number of speaker pods in your cluster might differ from the example output. Make sure the output indicates one pod for each node in your cluster.

26.2.3.1. Limit speaker pods to specific nodes

By default, when you start MetalLB with the MetalLB Operator, the Operator starts an instance of a speaker pod on each node in the cluster. Only the nodes with a speaker pod can advertise a load balancer IP address. You can configure the MetalLB custom resource with a node selector to specify which nodes run the speaker pods.

The most common reason to limit the speaker pods to specific nodes is to ensure that only nodes with network interfaces on specific networks advertise load balancer IP addresses. Only the nodes with a running speaker pod are advertised as destinations of the load balancer IP address.

If you limit the speaker pods to specific nodes and specify local for the external traffic policy of a service, then you must ensure that the application pods for the service are deployed to the same nodes.

Example configuration to limit speaker pods to worker nodes

apiVersion: metallb.io/v1beta1
kind: MetalLB
metadata:
  name: metallb
  namespace: metallb-system
spec:
  nodeSelector:  <.>
    node-role.kubernetes.io/worker: ""
  speakerTolerations:   <.>
  - key: "Example"
    operator: "Exists"
    effect: "NoExecute"

<.> The example configuration specifies to assign the speaker pods to worker nodes, but you can specify labels that you assigned to nodes or any valid node selector. <.> In this example configuration, the pod that this toleration is attached to tolerates any taint that matches the key value and effect value using the operator.

After you apply a manifest with the spec.nodeSelector field, you can check the number of pods that the Operator deployed with the oc get daemonset -n metallb-system speaker command. Similarly, you can display the nodes that match your labels with a command like oc get nodes -l node-role.kubernetes.io/worker=.

You can optionally allow the node to control which speaker pods should, or should not, be scheduled on them by using affinity rules. You can also limit these pods by applying a list of tolerations. For more information about affinity rules, taints, and tolerations, see the additional resources.

Additional resources

26.2.4. Next steps

26.3. Configuring MetalLB address pools

As a cluster administrator, you can add, modify, and delete address pools. The MetalLB Operator uses the address pool custom resources to set the IP addresses that MetalLB can assign to services.

26.3.1. About the address pool custom resource

The fields for the address pool custom resource are described in the following table.

Table 26.1. MetalLB address pool custom resource
FieldTypeDescription

metadata.name

string

Specifies the name for the address pool. When you add a service, you can specify this pool name in the metallb.universe.tf/address-pool annotation to select an IP address from a specific pool. The names doc-example, silver, and gold are used throughout the documentation.

metadata.namespace

string

Specifies the namespace for the address pool. Specify the same namespace that the MetalLB Operator uses.

spec.protocol

string

Specifies the protocol for announcing the load balancer IP address to peer nodes. Specify layer2 or bgp.

spec.autoAssign

boolean

Optional: Specifies whether MetalLB automatically assigns IP addresses from this pool. Specify false if you want explicitly request an IP address from this pool with the metallb.universe.tf/address-pool annotation. The default value is true.

spec.addresses

array

Specifies a list of IP addresses for MetalLB to assign to services. You can specify multiple ranges in a single pool. Specify each range in CIDR notation or as starting and ending IP addresses separated with a hyphen.

spec.bgpAdvertisements

object

Optional: By default, BGP mode advertises each allocated load-balancer IP address to the configured peers with no additional BGP attributes. The peer routers receive one /32 route for each service IP address, with the BGP local preference set to zero and no BGP communities. Use this field to create custom advertisements.

The fields for the bgpAdvertisements object are defined in the following table:

Table 26.2. BGP advertisements configuration
FieldTypeDescription

aggregationLength

integer

Optional: Specifies the number of bits to include in a 32-bit CIDR mask. To aggregate the routes that the speaker advertises to BGP peers, the mask is applied to the routes for several service IP addresses and the speaker advertises the aggregated route. For example, with an aggregation length of 24, the speaker can aggregate several 10.0.1.x/32 service IP addresses and advertise a single 10.0.1.0/24 route.

aggregationLengthV6

integer

Optional: Specifies the number of bits to include in a 128-bit CIDR mask. For example, with an aggregation length of 124, the speaker can aggregate several fc00:f853:0ccd:e799::x/128 service IP addresses and advertise a single fc00:f853:0ccd:e799::0/124 route.

community

array

Optional: Specifies one or more BGP communities. Each community is specified as two 16-bit values separated by the colon character. Well-known communities must be specified as 16-bit values:

  • NO_EXPORT: 65535:65281
  • NO_ADVERTISE: 65535:65282
  • NO_EXPORT_SUBCONFED: 65535:65283

localPref

integer

Optional: Specifies the local preference for this advertisement. This BGP attribute applies to BGP sessions within the Autonomous System.

26.3.2. Configuring an address pool

As a cluster administrator, you can add address pools to your cluster to control the IP addresses that MetalLB can assign to load-balancer services.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.

Procedure

  1. Create a file, such as addresspool.yaml, with content like the following example:

    apiVersion: metallb.io/v1alpha1
    kind: AddressPool
    metadata:
      namespace: metallb-system
      name: doc-example
    spec:
      protocol: layer2
      addresses:
      - 203.0.113.1-203.0.113.10
      - 203.0.113.65-203.0.113.75
  2. Apply the configuration for the address pool:

    $ oc apply -f addresspool.yaml

Verification

  • View the address pool:

    $ oc describe -n metallb-system addresspool doc-example

    Example output

    Name:         doc-example
    Namespace:    metallb-system
    Labels:       <none>
    Annotations:  <none>
    API Version:  metallb.io/v1alpha1
    Kind:         AddressPool
    Metadata:
      ...
    Spec:
      Addresses:
        203.0.113.1-203.0.113.10
        203.0.113.65-203.0.113.75
      Auto Assign:  true
      Protocol:     layer2
    Events:         <none>

Confirm that the address pool name, such as doc-example, and the IP address ranges appear in the output.

26.3.3. Example address pool configurations

26.3.3.1. Example: IPv4 and CIDR ranges

You can specify a range of IP addresses in CIDR notation. You can combine CIDR notation with the notation that uses a hyphen to separate lower and upper bounds.

apiVersion: metallb.io/v1beta1
kind: AddressPool
metadata:
  name: doc-example-cidr
  namespace: metallb-system
spec:
  protocol: layer2
  addresses:
  - 192.168.100.0/24
  - 192.168.200.0/24
  - 192.168.255.1-192.168.255.5

26.3.3.2. Example: Reserve IP addresses

You can set the autoAssign field to false to prevent MetalLB from automatically assigning the IP addresses from the pool. When you add a service, you can request a specific IP address from the pool or you can specify the pool name in an annotation to request any IP address from the pool.

apiVersion: metallb.io/v1beta1
kind: AddressPool
metadata:
  name: doc-example-reserved
  namespace: metallb-system
spec:
  protocol: layer2
  addresses:
  - 10.0.100.0/28
  autoAssign: false

26.3.3.3. Example: IPv4 and IPv6 addresses

You can add address pools that use IPv4 and IPv6. You can specify multiple ranges in the addresses list, just like several IPv4 examples.

Whether the service is assigned a single IPv4 address, a single IPv6 address, or both is determined by how you add the service. The spec.ipFamilies and spec.ipFamilyPolicy fields control how IP addresses are assigned to the service.

apiVersion: metallb.io/v1beta1
kind: AddressPool
metadata:
  name: doc-example-combined
  namespace: metallb-system
spec:
  protocol: layer2
  addresses:
  - 10.0.100.0/28
  - 2002:2:2::1-2002:2:2::100

26.3.3.4. Example: Simple address pool with BGP mode

For BGP mode, you must set the protocol field set to bgp. Other address pool custom resource fields, such as autoAssign, also apply to BGP mode.

In the following example, the peer BGP routers receive one 203.0.113.200/32 route and one fc00:f853:ccd:e799::1/128 route for each load-balancer IP address that MetalLB assigns to a service. Because the localPref and communities fields are not specified, the routes are advertised with localPref set to zero and no BGP communities.

apiVersion: metallb.io/v1beta1
kind: AddressPool
metadata:
  name: doc-example-bgp
  namespace: metallb-system
spec:
  protocol: bgp
  addresses:
    - 203.0.113.200/30
    - fc00:f853:ccd:e799::/124

26.3.3.5. Example: BGP mode with custom advertisement

You can specify sophisticated custom advertisements.

apiVersion: metallb.io/v1beta1
kind: AddressPool
metadata:
  name: doc-example-bgp-adv
  namespace: metallb-system
spec:
  protocol: bgp
  addresses:
    - 203.0.113.200/30
    - fc00:f853:ccd:e799::/124
  bgpAdvertisements:
  - communities:
    - 65535:65282
    aggregationLength: 32
    localPref: 100
  - communities:
    - 8000:800
    aggregationLength: 30
    aggregationLengthV6: 124

In the preceding example, MetalLB assigns IP addresses to load-balancer services in the ranges between 203.0.113.200 and 203.0.113.203 and between fc00:f853:ccd:e799::0 and fc00:f853:ccd:e799::f.

To explain the two BGP advertisements, consider an instance when MetalLB assigns the IP address of 203.0.113.200 to a service. With that IP address as an example, the speaker advertises two routes to BGP peers:

  • 203.0.113.200/32, with localPref set to 100 and the community set to the numeric value of the well-known NO_ADVERTISE community. This specification indicates to the peer routers that they can use this route but they should not propagate information about this route to BGP peers.
  • 203.0.113.200/30, aggregates the load-balancer IP addresses assigned by MetalLB into a single route. MetalLB advertises the aggregated route to BGP peers with the community attribute set to 8000:800. BGP peers propagate the 203.0.113.200/30 route to other BGP peers. When traffic is routed to a node with a speaker, the 203.0.113.200/32 route is used to forward the traffic into the cluster and to a pod that is associated with the service.

As you add more services and MetalLB assigns more load-balancer IP addresses from the pool, peer routers receive one local route, 203.0.113.20x/32, for each service, as well as the 203.0.113.200/30 aggregate route. Each service that you add generates the /30 route, but MetalLB deduplicates the routes to one BGP advertisement before communicating with peer routers.

26.3.4. Next steps

26.4. Configuring MetalLB BGP peers

As a cluster administrator, you can add, modify, and delete Border Gateway Protocol (BGP) peers. The MetalLB Operator uses the BGP peer custom resources to identify which peers that MetalLB speaker pods contact to start BGP sessions. The peers receive the route advertisements for the load-balancer IP addresses that MetalLB assigns to services.

26.4.1. About the BGP peer custom resource

The fields for the BGP peer custom resource are described in the following table.

Table 26.3. MetalLB BGP peer custom resource
FieldTypeDescription

metadata.name

string

Specifies the name for the BGP peer custom resource.

metadata.namespace

string

Specifies the namespace for the BGP peer custom resource.

spec.myASN

integer

Specifies the Autonomous System number for the local end of the BGP session. Specify the same value in all BGP peer custom resources that you add. The range is 0 to 65535.

spec.peerASN

integer

Specifies the Autonomous System number for the remote end of the BGP session. The range is 0 to 65535.

spec.peerAddress

string

Specifies the IP address of the peer to contact for establishing the BGP session.

spec.sourceAddress

string

Optional: Specifies the IP address to use when establishing the BGP session. The value must be an IPv4 address.

spec.peerPort

integer

Optional: Specifies the network port of the peer to contact for establishing the BGP session. The range is 0 to 16384.

spec.holdTime

string

Optional: Specifies the duration for the hold time to propose to the BGP peer. The minimum value is 3 seconds (3s). The common units are seconds and minutes, such as 3s, 1m, and 5m30s. To detect path failures more quickly, also configure BFD.

spec.keepaliveTime

string

Optional: Specifies the maximum interval between sending keep-alive messages to the BGP peer. If you specify this field, you must also specify a value for the holdTime field. The specified value must be less than the value for the holdTime field.

spec.routerID

string

Optional: Specifies the router ID to advertise to the BGP peer. If you specify this field, you must specify the same value in every BGP peer custom resource that you add.

spec.password

string

Optional: Specifies the MD5 password to send to the peer for routers that enforce TCP MD5 authenticated BGP sessions.

spec.bfdProfile

string

Optional: Specifies the name of a BFD profile.

spec.nodeSelectors

object[]

Optional: Specifies a selector, using match expressions and match labels, to control which nodes can connect to the BGP peer.

spec.ebgpMultiHop

boolean

Optional: Specifies that the BGP peer is multiple network hops away. If the BGP peer is not directly connected to the same network, the speaker cannot establish a BGP session unless this field is set to true. This field applies to external BGP. External BGP is the term that is used to describe when a BGP peer belongs to a different Autonomous System.

26.4.2. Configuring a BGP peer

As a cluster administrator, you can add a BGP peer custom resource to exchange routing information with network routers and advertise the IP addresses for services.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Configure a MetalLB address pool that specifies bgp for the spec.protocol field.

Procedure

  1. Create a file, such as bgppeer.yaml, with content like the following example:

    apiVersion: metallb.io/v1beta1
    kind: BGPPeer
    metadata:
      namespace: metallb-system
      name: doc-example-peer
    spec:
      peerAddress: 10.0.0.1
      peerASN: 64501
      myASN: 64500
      routerID: 10.10.10.10
  2. Apply the configuration for the BGP peer:

    $ oc apply -f bgppeer.yaml

Additional resources

26.4.3. Example BGP peer configurations

26.4.3.1. Example: Limit which nodes connect to a BGP peer

You can specify the node selectors field to control which nodes can connect to a BGP peer.

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-nodesel
  namespace: metallb-system
spec:
  peerAddress: 10.0.20.1
  peerASN: 64501
  myASN: 64500
  nodeSelectors:
  - matchExpressions:
    - key: kubernetes.io/hostname
      operator: In
      values: [compute-1.example.com, compute-2.example.com]

26.4.3.2. Example: Specify a BFD profile for a BGP peer

You can specify a BFD profile to associate with BGP peers. BFD compliments BGP by providing more rapid detection of communication failures between peers than BGP alone.

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-peer-bfd
  namespace: metallb-system
spec:
  peerAddress: 10.0.20.1
  peerASN: 64501
  myASN: 64500
  holdTime: "10s"
  bfdProfile: doc-example-bfd-profile-full
Note

Deleting the bidirectional forwarding detection (BFD) profile and removing the bfdProfile added to the border gateway protocol (BGP) peer resource does not disable the BFD. Instead, the BGP peer starts using the default BFD profile. To disable BFD from a BGP peer resource, delete the BGP peer configuration and recreate it without a BFD profile. For more information, see BZ#2050824.

26.4.3.3. Example: Specify BGP peers for dual-stack networking

To support dual-stack networking, add one BGP peer custom resource for IPv4 and one BGP peer custom resource for IPv6.

apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-dual-stack-ipv4
  namespace: metallb-system
spec:
  peerAddress: 10.0.20.1
  peerASN: 64500
  myASN: 64500
---
apiVersion: metallb.io/v1beta1
kind: BGPPeer
metadata:
  name: doc-example-dual-stack-ipv6
  namespace: metallb-system
spec:
  peerAddress: 2620:52:0:88::104
  peerASN: 64500
  myASN: 64500

26.5. Configuring MetalLB BFD profiles

As a cluster administrator, you can add, modify, and delete Bidirectional Forwarding Detection (BFD) profiles. The MetalLB Operator uses the BFD profile custom resources to identify which BGP sessions use BFD to provide faster path failure detection than BGP alone provides.

26.5.1. About the BFD profile custom resource

The fields for the BFD profile custom resource are described in the following table.

Table 26.4. BFD profile custom resource
FieldTypeDescription

metadata.name

string

Specifies the name for the BFD profile custom resource.

metadata.namespace

string

Specifies the namespace for the BFD profile custom resource.

spec.detectMultiplier

integer

Specifies the detection multiplier to determine packet loss. The remote transmission interval is multiplied by this value to determine the connection loss detection timer.

For example, when the local system has the detect multiplier set to 3 and the remote system has the transmission interval set to 300, the local system detects failures only after 900 ms without receiving packets.

The range is 2 to 255. The default value is 3.

spec.echoMode

boolean

Specifies the echo transmission mode. If you are not using distributed BFD, echo transmission mode works only when the peer is also FRR. The default value is false and echo transmission mode is disabled.

When echo transmission mode is enabled, consider increasing the transmission interval of control packets to reduce bandwidth usage. For example, consider increasing the transmit interval to 2000 ms.

spec.echoInterval

integer

Specifies the minimum transmission interval, less jitter, that this system uses to send and receive echo packets. The range is 10 to 60000. The default value is 50 ms.

spec.minimumTtl

integer

Specifies the minimum expected TTL for an incoming control packet. This field applies to multi-hop sessions only.

The purpose of setting a minimum TTL is to make the packet validation requirements more stringent and avoid receiving control packets from other sessions.

The default value is 254 and indicates that the system expects only one hop between this system and the peer.

spec.passiveMode

boolean

Specifies whether a session is marked as active or passive. A passive session does not attempt to start the connection. Instead, a passive session waits for control packets from a peer before it begins to reply.

Marking a session as passive is useful when you have a router that acts as the central node of a star network and you want to avoid sending control packets that you do not need the system to send.

The default value is false and marks the session as active.

spec.receiveInterval

integer

Specifies the minimum interval that this system is capable of receiving control packets. The range is 10 to 60000. The default value is 300 ms.

spec.transmitInterval

integer

Specifies the minimum transmission interval, less jitter, that this system uses to send control packets. The range is 10 to 60000. The default value is 300 ms.

26.5.2. Configuring a BFD profile

As a cluster administrator, you can add a BFD profile and configure a BGP peer to use the profile. BFD provides faster path failure detection than BGP alone.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.

Procedure

  1. Create a file, such as bfdprofile.yaml, with content like the following example:

    apiVersion: metallb.io/v1beta1
    kind: BFDProfile
    metadata:
      name: doc-example-bfd-profile-full
      namespace: metallb-system
    spec:
      receiveInterval: 300
      transmitInterval: 300
      detectMultiplier: 3
      echoMode: false
      passiveMode: true
      minimumTtl: 254
  2. Apply the configuration for the BFD profile:

    $ oc apply -f bfdprofile.yaml

26.5.3. Next steps

26.6. Configuring services to use MetalLB

As a cluster administrator, when you add a service of type LoadBalancer, you can control how MetalLB assigns an IP address.

26.6.1. Request a specific IP address

Like some other load-balancer implementations, MetalLB accepts the spec.loadBalancerIP field in the service specification.

If the requested IP address is within a range from any address pool, MetalLB assigns the requested IP address. If the requested IP address is not within any range, MetalLB reports a warning.

Example service YAML for a specific IP address

apiVersion: v1
kind: Service
metadata:
  name: <service_name>
  annotations:
    metallb.universe.tf/address-pool: <address_pool_name>
spec:
  selector:
    <label_key>: <label_value>
  ports:
    - port: 8080
      targetPort: 8080
      protocol: TCP
  type: LoadBalancer
  loadBalancerIP: <ip_address>

If MetalLB cannot assign the requested IP address, the EXTERNAL-IP for the service reports <pending> and running oc describe service <service_name> includes an event like the following example.

Example event when MetalLB cannot assign a requested IP address

  ...
Events:
  Type     Reason            Age    From                Message
  ----     ------            ----   ----                -------
  Warning  AllocationFailed  3m16s  metallb-controller  Failed to allocate IP for "default/invalid-request": "4.3.2.1" is not allowed in config

26.6.2. Request an IP address from a specific pool

To assign an IP address from a specific range, but you are not concerned with the specific IP address, then you can use the metallb.universe.tf/address-pool annotation to request an IP address from the specified address pool.

Example service YAML for an IP address from a specific pool

apiVersion: v1
kind: Service
metadata:
  name: <service_name>
  annotations:
    metallb.universe.tf/address-pool: <address_pool_name>
spec:
  selector:
    <label_key>: <label_value>
  ports:
    - port: 8080
      targetPort: 8080
      protocol: TCP
  type: LoadBalancer

If the address pool that you specify for <address_pool_name> does not exist, MetalLB attempts to assign an IP address from any pool that permits automatic assignment.

26.6.3. Accept any IP address

By default, address pools are configured to permit automatic assignment. MetalLB assigns an IP address from these address pools.

To accept any IP address from any pool that is configured for automatic assignment, no special annotation or configuration is required.

Example service YAML for accepting any IP address

apiVersion: v1
kind: Service
metadata:
  name: <service_name>
spec:
  selector:
    <label_key>: <label_value>
  ports:
    - port: 8080
      targetPort: 8080
      protocol: TCP
  type: LoadBalancer

26.6.4. Share a specific IP address

By default, services do not share IP addresses. However, if you need to colocate services on a single IP address, you can enable selective IP sharing by adding the metallb.universe.tf/allow-shared-ip annotation to the services.

apiVersion: v1
kind: Service
metadata:
  name: service-http
  annotations:
    metallb.universe.tf/address-pool: doc-example
    metallb.universe.tf/allow-shared-ip: "web-server-svc"  1
spec:
  ports:
    - name: http
      port: 80  2
      protocol: TCP
      targetPort: 8080
  selector:
    <label_key>: <label_value>  3
  type: LoadBalancer
  loadBalancerIP: 172.31.249.7  4
---
apiVersion: v1
kind: Service
metadata:
  name: service-https
  annotations:
    metallb.universe.tf/address-pool: doc-example
    metallb.universe.tf/allow-shared-ip: "web-server-svc"  5
spec:
  ports:
    - name: https
      port: 443  6
      protocol: TCP
      targetPort: 8080
  selector:
    <label_key>: <label_value>  7
  type: LoadBalancer
  loadBalancerIP: 172.31.249.7  8
1 5
Specify the same value for the metallb.universe.tf/allow-shared-ip annotation. This value is referred to as the sharing key.
2 6
Specify different port numbers for the services.
3 7
Specify identical pod selectors if you must specify externalTrafficPolicy: local so the services send traffic to the same set of pods. If you use the cluster external traffic policy, then the pod selectors do not need to be identical.
4 8
Optional: If you specify the three preceding items, MetalLB might colocate the services on the same IP address. To ensure that services share an IP address, specify the IP address to share.

By default, Kubernetes does not allow multiprotocol load balancer services. This limitation would normally make it impossible to run a service like DNS that needs to listen on both TCP and UDP. To work around this limitation of Kubernetes with MetalLB, create two services:

  • For one service, specify TCP and for the second service, specify UDP.
  • In both services, specify the same pod selector.
  • Specify the same sharing key and spec.loadBalancerIP value to colocate the TCP and UDP services on the same IP address.

26.6.5. Configuring a service with MetalLB

You can configure a load-balancing service to use an external IP address from an address pool.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Install the MetalLB Operator and start MetalLB.
  • Configure at least one address pool.
  • Configure your network to route traffic from the clients to the host network for the cluster.

Procedure

  1. Create a <service_name>.yaml file. In the file, ensure that the spec.type field is set to LoadBalancer.

    Refer to the examples for information about how to request the external IP address that MetalLB assigns to the service.

  2. Create the service:

    $ oc apply -f <service_name>.yaml

    Example output

    service/<service_name> created

Verification

  • Describe the service:

    $ oc describe service <service_name>

    Example output

    Name:                     <service_name>
    Namespace:                default
    Labels:                   <none>
    Annotations:              metallb.universe.tf/address-pool: doc-example  <.>
    Selector:                 app=service_name
    Type:                     LoadBalancer  <.>
    IP Family Policy:         SingleStack
    IP Families:              IPv4
    IP:                       10.105.237.254
    IPs:                      10.105.237.254
    LoadBalancer Ingress:     192.168.100.5  <.>
    Port:                     <unset>  80/TCP
    TargetPort:               8080/TCP
    NodePort:                 <unset>  30550/TCP
    Endpoints:                10.244.0.50:8080
    Session Affinity:         None
    External Traffic Policy:  Cluster
    Events:  <.>
      Type    Reason        Age                From             Message
      ----    ------        ----               ----             -------
      Normal  nodeAssigned  32m (x2 over 32m)  metallb-speaker  announcing from node "<node_name>"

    <.> The annotation is present if you request an IP address from a specific pool. <.> The service type must indicate LoadBalancer. <.> The load-balancer ingress field indicates the external IP address if the service is assigned correctly. <.> The events field indicates the node name that is assigned to announce the external IP address. If you experience an error, the events field indicates the reason for the error.

26.7. MetalLB logging, troubleshooting, and support

If you need to troubleshoot MetalLB configuration, see the following sections for commonly used commands.

26.7.1. Setting the MetalLB logging levels

MetalLB uses FRRouting (FRR) in a container with the default setting of info generates a lot of logging. You can control the verbosity of the logs generated by setting the logLevel as illustrated in this example.

Gain a deeper insight into MetalLB by setting the logLevel to debug as follows:

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.
  • You have installed the OpenShift CLI (oc).

Procedure

  1. Create a file, such as setdebugloglevel.yaml, with content like the following example:

    apiVersion: metallb.io/v1beta1
    kind: MetalLB
    metadata:
      name: metallb
      namespace: metallb-system
    spec:
      logLevel: debug
      nodeSelector:
        node-role.kubernetes.io/worker: ""
  2. Apply the configuration:

    $ oc replace -f setdebugloglevel.yaml
    Note

    Use oc replace as the understanding is the metallb CR is already created and here you are changing the log level.

  3. Display the names of the speaker pods:

    $ oc get -n metallb-system pods -l component=speaker

    Example output

    NAME                    READY   STATUS    RESTARTS   AGE
    speaker-2m9pm           4/4     Running   0          9m19s
    speaker-7m4qw           3/4     Running   0          19s
    speaker-szlmx           4/4     Running   0          9m19s

    Note

    Speaker and controller pods are recreated to ensure the updated logging level is applied. The logging level is modified for all the components of MetalLB.

  4. View the speaker logs:

    $ oc logs -n metallb-system speaker-7m4qw -c speaker

    Example output

    {"branch":"main","caller":"main.go:92","commit":"3d052535","goversion":"gc / go1.17.1 / amd64","level":"info","msg":"MetalLB speaker starting (commit 3d052535, branch main)","ts":"2022-05-17T09:55:05Z","version":""}
    {"caller":"announcer.go:110","event":"createARPResponder","interface":"ens4","level":"info","msg":"created ARP responder for interface","ts":"2022-05-17T09:55:05Z"}
    {"caller":"announcer.go:119","event":"createNDPResponder","interface":"ens4","level":"info","msg":"created NDP responder for interface","ts":"2022-05-17T09:55:05Z"}
    {"caller":"announcer.go:110","event":"createARPResponder","interface":"tun0","level":"info","msg":"created ARP responder for interface","ts":"2022-05-17T09:55:05Z"}
    {"caller":"announcer.go:119","event":"createNDPResponder","interface":"tun0","level":"info","msg":"created NDP responder for interface","ts":"2022-05-17T09:55:05Z"}
    I0517 09:55:06.515686      95 request.go:665] Waited for 1.026500832s due to client-side throttling, not priority and fairness, request: GET:https://172.30.0.1:443/apis/operators.coreos.com/v1alpha1?timeout=32s
    {"Starting Manager":"(MISSING)","caller":"k8s.go:389","level":"info","ts":"2022-05-17T09:55:08Z"}
    {"caller":"speakerlist.go:310","level":"info","msg":"node event - forcing sync","node addr":"10.0.128.4","node event":"NodeJoin","node name":"ci-ln-qb8t3mb-72292-7s7rh-worker-a-vvznj","ts":"2022-05-17T09:55:08Z"}
    {"caller":"service_controller.go:113","controller":"ServiceReconciler","enqueueing":"openshift-kube-controller-manager-operator/metrics","epslice":"{\"metadata\":{\"name\":\"metrics-xtsxr\",\"generateName\":\"metrics-\",\"namespace\":\"openshift-kube-controller-manager-operator\",\"uid\":\"ac6766d7-8504-492c-9d1e-4ae8897990ad\",\"resourceVersion\":\"9041\",\"generation\":4,\"creationTimestamp\":\"2022-05-17T07:16:53Z\",\"labels\":{\"app\":\"kube-controller-manager-operator\",\"endpointslice.kubernetes.io/managed-by\":\"endpointslice-controller.k8s.io\",\"kubernetes.io/service-name\":\"metrics\"},\"annotations\":{\"endpoints.kubernetes.io/last-change-trigger-time\":\"2022-05-17T07:21:34Z\"},\"ownerReferences\":[{\"apiVersion\":\"v1\",\"kind\":\"Service\",\"name\":\"metrics\",\"uid\":\"0518eed3-6152-42be-b566-0bd00a60faf8\",\"controller\":true,\"blockOwnerDeletion\":true}],\"managedFields\":[{\"manager\":\"kube-controller-manager\",\"operation\":\"Update\",\"apiVersion\":\"discovery.k8s.io/v1\",\"time\":\"2022-05-17T07:20:02Z\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:addressType\":{},\"f:endpoints\":{},\"f:metadata\":{\"f:annotations\":{\".\":{},\"f:endpoints.kubernetes.io/last-change-trigger-time\":{}},\"f:generateName\":{},\"f:labels\":{\".\":{},\"f:app\":{},\"f:endpointslice.kubernetes.io/managed-by\":{},\"f:kubernetes.io/service-name\":{}},\"f:ownerReferences\":{\".\":{},\"k:{\\\"uid\\\":\\\"0518eed3-6152-42be-b566-0bd00a60faf8\\\"}\":{}}},\"f:ports\":{}}}]},\"addressType\":\"IPv4\",\"endpoints\":[{\"addresses\":[\"10.129.0.7\"],\"conditions\":{\"ready\":true,\"serving\":true,\"terminating\":false},\"targetRef\":{\"kind\":\"Pod\",\"namespace\":\"openshift-kube-controller-manager-operator\",\"name\":\"kube-controller-manager-operator-6b98b89ddd-8d4nf\",\"uid\":\"dd5139b8-e41c-4946-a31b-1a629314e844\",\"resourceVersion\":\"9038\"},\"nodeName\":\"ci-ln-qb8t3mb-72292-7s7rh-master-0\",\"zone\":\"us-central1-a\"}],\"ports\":[{\"name\":\"https\",\"protocol\":\"TCP\",\"port\":8443}]}","level":"debug","ts":"2022-05-17T09:55:08Z"}

  5. View the FRR logs:

    $ oc logs -n metallb-system speaker-7m4qw -c frr

    Example output

    Started watchfrr
    2022/05/17 09:55:05 ZEBRA: client 16 says hello and bids fair to announce only bgp routes vrf=0
    2022/05/17 09:55:05 ZEBRA: client 31 says hello and bids fair to announce only vnc routes vrf=0
    2022/05/17 09:55:05 ZEBRA: client 38 says hello and bids fair to announce only static routes vrf=0
    2022/05/17 09:55:05 ZEBRA: client 43 says hello and bids fair to announce only bfd routes vrf=0
    2022/05/17 09:57:25.089 BGP: Creating Default VRF, AS 64500
    2022/05/17 09:57:25.090 BGP: dup addr detect enable max_moves 5 time 180 freeze disable freeze_time 0
    2022/05/17 09:57:25.090 BGP: bgp_get: Registering BGP instance (null) to zebra
    2022/05/17 09:57:25.090 BGP: Registering VRF 0
    2022/05/17 09:57:25.091 BGP: Rx Router Id update VRF 0 Id 10.131.0.1/32
    2022/05/17 09:57:25.091 BGP: RID change : vrf VRF default(0), RTR ID 10.131.0.1
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF br0
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF ens4
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF ens4 addr 10.0.128.4/32
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF ens4 addr fe80::c9d:84da:4d86:5618/64
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF lo
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF ovs-system
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF tun0
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF tun0 addr 10.131.0.1/23
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF tun0 addr fe80::40f1:d1ff:feb6:5322/64
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF veth2da49fed
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF veth2da49fed addr fe80::24bd:d1ff:fec1:d88/64
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF veth2fa08c8c
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF veth2fa08c8c addr fe80::6870:ff:fe96:efc8/64
    2022/05/17 09:57:25.091 BGP: Rx Intf add VRF 0 IF veth41e356b7
    2022/05/17 09:57:25.091 BGP: Rx Intf address add VRF 0 IF veth41e356b7 addr fe80::48ff:37ff:fede:eb4b/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF veth1295c6e2
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF veth1295c6e2 addr fe80::b827:a2ff:feed:637/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF veth9733c6dc
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF veth9733c6dc addr fe80::3cf4:15ff:fe11:e541/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF veth336680ea
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF veth336680ea addr fe80::94b1:8bff:fe7e:488c/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF vetha0a907b7
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF vetha0a907b7 addr fe80::3855:a6ff:fe73:46c3/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF vethf35a4398
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF vethf35a4398 addr fe80::40ef:2fff:fe57:4c4d/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF vethf831b7f4
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF vethf831b7f4 addr fe80::f0d9:89ff:fe7c:1d32/64
    2022/05/17 09:57:25.092 BGP: Rx Intf add VRF 0 IF vxlan_sys_4789
    2022/05/17 09:57:25.092 BGP: Rx Intf address add VRF 0 IF vxlan_sys_4789 addr fe80::80c1:82ff:fe4b:f078/64
    2022/05/17 09:57:26.094 BGP: 10.0.0.1 [FSM] Timer (start timer expire).
    2022/05/17 09:57:26.094 BGP: 10.0.0.1 [FSM] BGP_Start (Idle->Connect), fd -1
    2022/05/17 09:57:26.094 BGP: Allocated bnc 10.0.0.1/32(0)(VRF default) peer 0x7f807f7631a0
    2022/05/17 09:57:26.094 BGP: sendmsg_zebra_rnh: sending cmd ZEBRA_NEXTHOP_REGISTER for 10.0.0.1/32 (vrf VRF default)
    2022/05/17 09:57:26.094 BGP: 10.0.0.1 [FSM] Waiting for NHT
    2022/05/17 09:57:26.094 BGP: bgp_fsm_change_status : vrf default(0), Status: Connect established_peers 0
    2022/05/17 09:57:26.094 BGP: 10.0.0.1 went from Idle to Connect
    2022/05/17 09:57:26.094 BGP: 10.0.0.1 [FSM] TCP_connection_open_failed (Connect->Active), fd -1
    2022/05/17 09:57:26.094 BGP: bgp_fsm_change_status : vrf default(0), Status: Active established_peers 0
    2022/05/17 09:57:26.094 BGP: 10.0.0.1 went from Connect to Active
    2022/05/17 09:57:26.094 ZEBRA: rnh_register msg from client bgp: hdr->length=8, type=nexthop vrf=0
    2022/05/17 09:57:26.094 ZEBRA: 0: Add RNH 10.0.0.1/32 type Nexthop
    2022/05/17 09:57:26.094 ZEBRA: 0:10.0.0.1/32: Evaluate RNH, type Nexthop (force)
    2022/05/17 09:57:26.094 ZEBRA: 0:10.0.0.1/32: NH has become unresolved
    2022/05/17 09:57:26.094 ZEBRA: 0: Client bgp registers for RNH 10.0.0.1/32 type Nexthop
    2022/05/17 09:57:26.094 BGP: VRF default(0): Rcvd NH update 10.0.0.1/32(0) - metric 0/0 #nhops 0/0 flags 0x6
    2022/05/17 09:57:26.094 BGP: NH update for 10.0.0.1/32(0)(VRF default) - flags 0x6 chgflags 0x0 - evaluate paths
    2022/05/17 09:57:26.094 BGP: evaluate_paths: Updating peer (10.0.0.1(VRF default)) status with NHT
    2022/05/17 09:57:30.081 ZEBRA: Event driven route-map update triggered
    2022/05/17 09:57:30.081 ZEBRA: Event handler for route-map: 10.0.0.1-out
    2022/05/17 09:57:30.081 ZEBRA: Event handler for route-map: 10.0.0.1-in
    2022/05/17 09:57:31.104 ZEBRA: netlink_parse_info: netlink-listen (NS 0) type RTM_NEWNEIGH(28), len=76, seq=0, pid=0
    2022/05/17 09:57:31.104 ZEBRA: 	Neighbor Entry received is not on a VLAN or a BRIDGE, ignoring
    2022/05/17 09:57:31.105 ZEBRA: netlink_parse_info: netlink-listen (NS 0) type RTM_NEWNEIGH(28), len=76, seq=0, pid=0
    2022/05/17 09:57:31.105 ZEBRA: 	Neighbor Entry received is not on a VLAN or a BRIDGE, ignoring

26.7.1.1. FRRouting (FRR) log levels

The following table describes the FRR logging levels.

Table 26.5. Log levels
Log levelDescription

all

Supplies all logging information for all logging levels.

debug

Information that is diagnostically helpful to people. Set to debug to give detailed troubleshooting information.

info

Provides information that always should be logged but under normal circumstances does not require user intervention. This is the default logging level.

warn

Anything that can potentially cause inconsistent MetalLB behaviour. Usually MetalLB automatically recovers from this type of error.

error

Any error that is fatal to the functioning of MetalLB. These errors usually require administrator intervention to fix.

none

Turn off all logging.

26.7.2. Troubleshooting BGP issues

The BGP implementation that Red Hat supports uses FRRouting (FRR) in a container in the speaker pods. As a cluster administrator, if you need to troubleshoot BGP configuration issues, you need to run commands in the FRR container.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.
  • You have installed the OpenShift CLI (oc).

Procedure

  1. Display the names of the speaker pods:

    $ oc get -n metallb-system pods -l app.kubernetes.io/component=speaker

    Example output

    NAME            READY   STATUS    RESTARTS   AGE
    speaker-66bth   4/4     Running   0          56m
    speaker-gvfnf   4/4     Running   0          56m
    ...

  2. Display the running configuration for FRR:

    $ oc exec -n metallb-system speaker-66bth -c frr -- vtysh -c "show running-config"

    Example output

    Building configuration...
    
    Current configuration:
    !
    frr version 7.5.1_git
    frr defaults traditional
    hostname some-hostname
    log file /etc/frr/frr.log informational
    log timestamp precision 3
    service integrated-vtysh-config
    !
    router bgp 64500  1
     bgp router-id 10.0.1.2
     no bgp ebgp-requires-policy
     no bgp default ipv4-unicast
     no bgp network import-check
     neighbor 10.0.2.3 remote-as 64500  2
     neighbor 10.0.2.3 bfd profile doc-example-bfd-profile-full  3
     neighbor 10.0.2.3 timers 5 15
     neighbor 10.0.2.4 remote-as 64500  4
     neighbor 10.0.2.4 bfd profile doc-example-bfd-profile-full  5
     neighbor 10.0.2.4 timers 5 15
     !
     address-family ipv4 unicast
      network 203.0.113.200/30   6
      neighbor 10.0.2.3 activate
      neighbor 10.0.2.3 route-map 10.0.2.3-in in
      neighbor 10.0.2.4 activate
      neighbor 10.0.2.4 route-map 10.0.2.4-in in
     exit-address-family
     !
     address-family ipv6 unicast
      network fc00:f853:ccd:e799::/124  7
      neighbor 10.0.2.3 activate
      neighbor 10.0.2.3 route-map 10.0.2.3-in in
      neighbor 10.0.2.4 activate
      neighbor 10.0.2.4 route-map 10.0.2.4-in in
     exit-address-family
    !
    route-map 10.0.2.3-in deny 20
    !
    route-map 10.0.2.4-in deny 20
    !
    ip nht resolve-via-default
    !
    ipv6 nht resolve-via-default
    !
    line vty
    !
    bfd
     profile doc-example-bfd-profile-full  8
      transmit-interval 35
      receive-interval 35
      passive-mode
      echo-mode
      echo-interval 35
      minimum-ttl 10
     !
    !
    end

    <.> The router bgp section indicates the ASN for MetalLB. <.> Confirm that a neighbor <ip-address> remote-as <peer-ASN> line exists for each BGP peer custom resource that you added. <.> If you configured BFD, confirm that the BFD profile is associated with the correct BGP peer and that the BFD profile appears in the command output. <.> Confirm that the network <ip-address-range> lines match the IP address ranges that you specified in address pool custom resources that you added.

  3. Display the BGP summary:

    $ oc exec -n metallb-system speaker-66bth -c frr -- vtysh -c "show bgp summary"

    Example output

    IPv4 Unicast Summary:
    BGP router identifier 10.0.1.2, local AS number 64500 vrf-id 0
    BGP table version 1
    RIB entries 1, using 192 bytes of memory
    Peers 2, using 29 KiB of memory
    
    Neighbor        V         AS   MsgRcvd   MsgSent   TblVer  InQ OutQ  Up/Down State/PfxRcd   PfxSnt
    10.0.2.3        4      64500       387       389        0    0    0 00:32:02            0        1  1
    10.0.2.4        4      64500         0         0        0    0    0    never       Active        0  2
    
    Total number of neighbors 2
    
    IPv6 Unicast Summary:
    BGP router identifier 10.0.1.2, local AS number 64500 vrf-id 0
    BGP table version 1
    RIB entries 1, using 192 bytes of memory
    Peers 2, using 29 KiB of memory
    
    Neighbor        V         AS   MsgRcvd   MsgSent   TblVer  InQ OutQ  Up/Down State/PfxRcd   PfxSnt
    10.0.2.3        4      64500       387       389        0    0    0 00:32:02 NoNeg  3
    10.0.2.4        4      64500         0         0        0    0    0    never       Active        0  4
    
    Total number of neighbors 2

    1 1 3
    Confirm that the output includes a line for each BGP peer custom resource that you added.
    2 4 2 4
    Output that shows 0 messages received and messages sent indicates a BGP peer that does not have a BGP session. Check network connectivity and the BGP configuration of the BGP peer.
  4. Display the BGP peers that received an address pool:

    $ oc exec -n metallb-system speaker-66bth -c frr -- vtysh -c "show bgp ipv4 unicast 203.0.113.200/30"

    Replace ipv4 with ipv6 to display the BGP peers that received an IPv6 address pool. Replace 203.0.113.200/30 with an IPv4 or IPv6 IP address range from an address pool.

    Example output

    BGP routing table entry for 203.0.113.200/30
    Paths: (1 available, best #1, table default)
      Advertised to non peer-group peers:
      10.0.2.3  <.>
      Local
        0.0.0.0 from 0.0.0.0 (10.0.1.2)
          Origin IGP, metric 0, weight 32768, valid, sourced, local, best (First path received)
          Last update: Mon Jan 10 19:49:07 2022

    <.> Confirm that the output includes an IP address for a BGP peer.

26.7.3. Troubleshooting BFD issues

The Bidirectional Forwarding Detection (BFD) implementation that Red Hat supports uses FRRouting (FRR) in a container in the speaker pods. The BFD implementation relies on BFD peers also being configured as BGP peers with an established BGP session. As a cluster administrator, if you need to troubleshoot BFD configuration issues, you need to run commands in the FRR container.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.
  • You have installed the OpenShift CLI (oc).

Procedure

  1. Display the names of the speaker pods:

    $ oc get -n metallb-system pods -l app.kubernetes.io/component=speaker

    Example output

    NAME            READY   STATUS    RESTARTS   AGE
    speaker-66bth   4/4     Running   0          26m
    speaker-gvfnf   4/4     Running   0          26m
    ...

  2. Display the BFD peers:

    $ oc exec -n metallb-system speaker-66bth -c frr -- vtysh -c "show bfd peers brief"

    Example output

    Session count: 2
    SessionId  LocalAddress              PeerAddress              Status
    =========  ============              ===========              ======
    3909139637 10.0.1.2                  10.0.2.3                 up  <.>

    <.> Confirm that the PeerAddress column includes each BFD peer. If the output does not list a BFD peer IP address that you expected the output to include, troubleshoot BGP connectivity with the peer. If the status field indicates down, check for connectivity on the links and equipment between the node and the peer. You can determine the node name for the speaker pod with a command like oc get pods -n metallb-system speaker-66bth -o jsonpath='{.spec.nodeName}'.

26.7.4. MetalLB metrics for BGP and BFD

OpenShift Container Platform captures the following metrics that are related to MetalLB and BGP peers and BFD profiles:

  • metallb_bfd_control_packet_input counts the number of BFD control packets received from each BFD peer.
  • metallb_bfd_control_packet_output counts the number of BFD control packets sent to each BFD peer.
  • metallb_bfd_echo_packet_input counts the number of BFD echo packets received from each BFD peer.
  • metallb_bfd_echo_packet_output counts the number of BFD echo packets sent to each BFD peer.
  • metallb_bfd_session_down_events counts the number of times the BFD session with a peer entered the down state.
  • metallb_bfd_session_up indicates the connection state with a BFD peer. 1 indicates the session is up and 0 indicates the session is down.
  • metallb_bfd_session_up_events counts the number of times the BFD session with a peer entered the up state.
  • metallb_bfd_zebra_notifications counts the number of BFD Zebra notifications for each BFD peer.
  • metallb_bgp_announced_prefixes_total counts the number of load balancer IP address prefixes that are advertised to BGP peers. The terms prefix and aggregated route have the same meaning.
  • metallb_bgp_session_up indicates the connection state with a BGP peer. 1 indicates the session is up and 0 indicates the session is down.
  • metallb_bgp_updates_total counts the number of BGP update messages that were sent to a BGP peer.

Additional resources

26.7.5. About collecting MetalLB data

You can use the oc adm must-gather CLI command to collect information about your cluster, your MetalLB configuration, and the MetalLB Operator. The following features and objects are associated with MetalLB and the MetalLB Operator:

  • The namespace and child objects that the MetalLB Operator is deployed in
  • All MetalLB Operator custom resource definitions (CRDs)

The oc adm must-gather CLI command collects the following information from FRRouting (FRR) that Red Hat uses to implement BGP and BFD:

  • /etc/frr/frr.conf
  • /etc/frr/frr.log
  • /etc/frr/daemons configuration file
  • /etc/frr/vtysh.conf

The log and configuration files in the preceding list are collected from the frr container in each speaker pod.

In addition to the log and configuration files, the oc adm must-gather CLI command collects the output from the following vtysh commands:

  • show running-config
  • show bgp ipv4
  • show bgp ipv6
  • show bgp neighbor
  • show bfd peer

No additional configuration is required when you run the oc adm must-gather CLI command.

Additional resources

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