Chapter 1. Configuring system controls and interface attributes using the tuning plugin

Procedure

1. Create a network attachment definition, such as tuning-example.yaml, with the following content:

   apiVersion: "k8s.cni.cncf.io/v1"
   kind: NetworkAttachmentDefinition
   metadata:
     name: <name>
     namespace: default
   spec:
     config: '{
       "cniVersion": "0.4.0",
       "name": "<name>",
       "plugins": [{
          "type": "<main_CNI_plugin>"
         },
         {
          "type": "tuning",
          "sysctl": {
               "net.ipv4.conf.IFNAME.accept_redirects": "1"
           }
         }
        ]
   }

   where:

   metadata.name

   Specifies the name for the additional network attachment to create. The name must be unique within the specified namespace.

   metadata.namespace

   Specifies the namespace that the object is associated with.

   spec.config.cniVersion

   Specifies the CNI specification version.

   spec.config.name

   Specifies the name for the configuration. It is recommended to match the configuration name to the name value of the network attachment definition.

   spec.config.plugins.type

   Specifies the name of the main CNI plugin to configure.

   spec.config.plugins.tuning.sysctl

   Specifies the sysctl to set. The interface name is represented by the IFNAME token and is replaced with the actual name of the interface at runtime.

   Example network attachment definition

   apiVersion: "k8s.cni.cncf.io/v1"
   kind: NetworkAttachmentDefinition
   metadata:
     name: tuningnad
     namespace: default
   spec:
     config: '{
       "cniVersion": "0.4.0",
       "name": "tuningnad",
       "plugins": [{
         "type": "bridge"
         },
         {
         "type": "tuning",
         "sysctl": {
            "net.ipv4.conf.IFNAME.accept_redirects": "1"
           }
       }
     ]
   }'

2. Apply the YAML by running the following command:

   $ oc apply -f tuning-example.yaml

   Example output

   networkattachmentdefinition.k8.cni.cncf.io/tuningnad created

3. Create a pod such as examplepod.yaml with the network attachment definition similar to the following:

   apiVersion: v1
   kind: Pod
   metadata:
     name: tunepod
     namespace: default
     annotations:
       k8s.v1.cni.cncf.io/networks: tuningnad
   spec:
     containers:
     - name: podexample
       image: centos
       command: ["/bin/bash", "-c", "sleep INF"]
       securityContext:
         runAsUser: 2000
         runAsGroup: 3000
         allowPrivilegeEscalation: false
         capabilities:
           drop: ["ALL"]
     securityContext:
       runAsNonRoot: true
       seccompProfile:
         type: RuntimeDefault

   where:

   metadata.annotations.k8s.v1.cni.cncf.io/networks

   Specifies the name of the configured NetworkAttachmentDefinition.

   spec.containers.securityContext.runAsUser

   Specifies which user ID the container is run with.

   spec.containers.securityContext.runAsGroup

   Specifies which primary group ID the containers is run with.

   spec.containers.securityContext.allowPrivilegeEscalation

   Specifies if a pod can request to allow privilege escalation. If unspecified, it defaults to true. This boolean directly controls whether the no_new_privs flag gets set on the container process.

   spec.containers.securityContext.capabilities

   Specifies privileged actions without giving full root access. This policy ensures all capabilities are dropped from the pod.

   spec.securityContext.runAsNonRoot: true

   Specifies that the container will run with a user with any UID other than 0.

   spec.securityContext.seccompProfile

   Specifies the default seccomp profile for a pod or container workload.

4. Apply the yaml by running the following command:

   $ oc apply -f examplepod.yaml

5. Verify that the pod is created by running the following command:

   $ oc get pod

   Example output

   NAME      READY   STATUS    RESTARTS   AGE
   tunepod   1/1     Running   0          47s

6. Log in to the pod by running the following command:

   $ oc rsh tunepod

7. Verify the values of the configured sysctl flags. For example, find the value net.ipv4.conf.net1.accept_redirects by running the following command:

   sh-4.4# sysctl net.ipv4.conf.net1.accept_redirects

   Expected output

   net.ipv4.conf.net1.accept_redirects = 1

Procedure

1. Create a network attachment definition, such as tuning-example.yaml, with the following content:

   apiVersion: "k8s.cni.cncf.io/v1"
   kind: NetworkAttachmentDefinition
   metadata:
     name: <name>
     namespace: default
   spec:
     config: '{
       "cniVersion": "0.4.0",
       "name": "<name>",
       "plugins": [{
          "type": "<main_CNI_plugin>"
         },
         {
          "type": "tuning",
          "allmulti": true
           }
         }
        ]
   }

   where:

   <name>

   Specifies the name for the additional network attachment to create. The name must be unique within the specified namespace.

   default

   Specifies the namespace that the object is associated with.

   "0.4.0"

   Specifies the CNI specification version.

   "<name>"

   Specifies the name for the configuration. Match the configuration name to the name value of the network attachment definition.

   "<main_CNI_plugin>"

   Specifies the name of the main CNI plugin to configure.

   "tuning"

   Specifies the name of the CNI meta plugin.

   "true"

   Specifies the all-multicast mode of interface. If enabled, all multicast packets on the network will be received by the interface.

   Example network attachment definition

   apiVersion: "k8s.cni.cncf.io/v1"
   kind: NetworkAttachmentDefinition
   metadata:
     name: setallmulti
     namespace: default
   spec:
     config: '{
       "cniVersion": "0.4.0",
       "name": "setallmulti",
       "plugins": [
         {
           "type": "bridge"
         },
         {
           "type": "tuning",
           "allmulti": true
         }
       ]
     }'

2. Apply the settings specified in the YAML file by running the following command:

   $ oc apply -f tuning-allmulti.yaml

   Example output

   networkattachmentdefinition.k8s.cni.cncf.io/setallmulti created

3. Create a pod with a network attachment definition similar to that specified in the following examplepod.yaml sample file:

   apiVersion: v1
   kind: Pod
   metadata:
     name: allmultipod
     namespace: default
     annotations:
       k8s.v1.cni.cncf.io/networks: setallmulti
   spec:
     containers:
     - name: podexample
       image: centos
       command: ["/bin/bash", "-c", "sleep INF"]
       securityContext:
         runAsUser: 2000
         runAsGroup: 3000
         allowPrivilegeEscalation: false
         capabilities:
           drop: ["ALL"]
     securityContext:
       runAsNonRoot: true
       seccompProfile:
         type: RuntimeDefault

   where:

   metadata.annotations.k8s.v1.cni.cncf.io/networks

   Specifies the name of the configured NetworkAttachmentDefinition.

   spec.containers.securityContext.runAsUser

   Specifies which user ID the container is run with.

   spec.containers.securityContext.runAsGroup

   Specifies which primary group ID the containers is run with.

   spec.containers.securityContext.allowPrivilegeEscalation

   Specifies if a pod can request to allow privilege escalation. If unspecified, it defaults to true. This boolean directly controls whether the no_new_privs flag gets set on the container process.

   spec.containers.securityContext.capabilities

   Specifies privileged actions without giving full root access. This policy ensures all capabilities are dropped from the pod.

   spec.containers.securityContext.runAsNonRoot: true

   Specifies that the container will run with a user with any UID other than 0.

   spec.containers.securityContext.seccompProfile

   Specifies the default seccomp profile for a pod or container workload.

4. Apply the settings specified in the YAML file by running the following command:

   $ oc apply -f examplepod.yaml

5. Verify that the pod is created by running the following command:

   $ oc get pod

   Example output

   NAME          READY   STATUS    RESTARTS   AGE
   allmultipod   1/1     Running   0          23s

6. Log in to the pod by running the following command:

   $ oc rsh allmultipod

7. List all the interfaces associated with the pod by running the following command:

   sh-4.4# ip link

   Example output

   1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
       link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
   2: eth0@if22: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 8901 qdisc noqueue state UP mode DEFAULT group default
       link/ether 0a:58:0a:83:00:10 brd ff:ff:ff:ff:ff:ff link-netnsid 0
   3: net1@if24: <BROADCAST,MULTICAST,ALLMULTI,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default
       link/ether ee:9b:66:a4:ec:1d brd ff:ff:ff:ff:ff:ff link-netnsid 0

   where:

   eth0@if22

   Specifies the primary interface.

   net1@if24

   Specifies the secondary interface configured with the network-attachment-definition that supports the all-multicast mode (ALLMULTI flag).