1.4. Creating a machine set on OpenStack
You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Red Hat OpenStack Platform (RHOSP). For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.
1.4.1. Machine API overview
The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.
For OpenShift Container Platform 4.5 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.5 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.
The two primary resources are:
- Machines
-
A fundamental unit that describes the host for a Node. A machine has a
providerSpecspecification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata. - Machine sets
-
MachineSetresources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.
The following custom resources add more capabilities to your cluster:
- Machine autoscaler
-
The
MachineAutoscalerresource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. TheMachineAutoscalerobject takes effect after aClusterAutoscalerobject exists. BothClusterAutoscalerandMachineAutoscalerresources are made available by theClusterAutoscalerOperatorobject. - Cluster autoscaler
- This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
- Machine health check
-
The
MachineHealthCheckresource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.
In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.
1.4.2. Sample YAML for a machine set custom resource on RHOSP
This sample YAML defines a machine set that runs on Red Hat OpenStack Platform (RHOSP) and creates nodes that are labeled with node-role.openshift.io/<node_role>: ""
In this sample, infrastructure_ID is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and node_role is the node label to add.
apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
labels:
machine.openshift.io/cluster-api-cluster: <infrastructure_ID> 1
machine.openshift.io/cluster-api-machine-role: <node_role> 2
machine.openshift.io/cluster-api-machine-type: <node_role> 3
name: <infrastructure_ID>-<node_role> 4
namespace: openshift-machine-api
spec:
replicas: <number_of_replicas>
selector:
matchLabels:
machine.openshift.io/cluster-api-cluster: <infrastructure_ID> 5
machine.openshift.io/cluster-api-machineset: <infrastructure_ID>-<node_role> 6
template:
metadata:
labels:
machine.openshift.io/cluster-api-cluster: <infrastructure_ID> 7
machine.openshift.io/cluster-api-machine-role: <node_role> 8
machine.openshift.io/cluster-api-machine-type: <node_role> 9
machine.openshift.io/cluster-api-machineset: <infrastructure_ID>-<node_role> 10
spec:
providerSpec:
value:
apiVersion: openstackproviderconfig.openshift.io/v1alpha1
cloudName: openstack
cloudsSecret:
name: openstack-cloud-credentials
namespace: openshift-machine-api
flavor: <nova_flavor>
image: <glance_image_name_or_location>
serverGroupID: <optional_UUID_of_server_group> 11
kind: OpenstackProviderSpec
networks:
- filter: {}
subnets:
- filter:
name: <subnet_name>
tags: openshiftClusterID=<infrastructure_ID>
securityGroups:
- filter: {}
name: <infrastructure_ID>-<node_role>
serverMetadata:
Name: <infrastructure_ID>-<node_role>
openshiftClusterID: <infrastructure_ID>
tags:
- openshiftClusterID=<infrastructure_ID>
trunk: true
userDataSecret:
name: <node_role>-user-data 12- 1 5 7
- Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster - 2 3 8 9 12
- Specify the node label to add.
- 4 6 10
- Specify the infrastructure ID and node label.
- 11
- To set a server group policy for the machine set, enter the value that is returned from creating a server group. For most deployments,
anti-affinityorsoft-anti-affinitypolicies are recommended.
1.4.3. Creating a machine set
In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.
Prerequisites
- Deploy an OpenShift Container Platform cluster.
-
Install the OpenShift CLI (
oc). -
Log in to
ocas a user withcluster-adminpermission.
Procedure
Create a new YAML file that contains the machine set custom resource (CR) sample, as shown, and is named
<file_name>.yaml.Ensure that you set the
<clusterID>and<role>parameter values.If you are not sure about which value to set for a specific field, you can check an existing machine set from your cluster.
$ oc get machinesets -n openshift-machine-api
Example output
NAME DESIRED CURRENT READY AVAILABLE AGE agl030519-vplxk-worker-us-east-1a 1 1 1 1 55m agl030519-vplxk-worker-us-east-1b 1 1 1 1 55m agl030519-vplxk-worker-us-east-1c 1 1 1 1 55m agl030519-vplxk-worker-us-east-1d 0 0 55m agl030519-vplxk-worker-us-east-1e 0 0 55m agl030519-vplxk-worker-us-east-1f 0 0 55m
Check values of a specific machine set:
$ oc get machineset <machineset_name> -n \ openshift-machine-api -o yamlExample output
... template: metadata: labels: machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1 machine.openshift.io/cluster-api-machine-role: worker 2 machine.openshift.io/cluster-api-machine-type: worker machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a
Create the new
MachineSetCR:$ oc create -f <file_name>.yaml
View the list of machine sets:
$ oc get machineset -n openshift-machine-api
Example output
NAME DESIRED CURRENT READY AVAILABLE AGE agl030519-vplxk-infra-us-east-1a 1 1 1 1 11m agl030519-vplxk-worker-us-east-1a 1 1 1 1 55m agl030519-vplxk-worker-us-east-1b 1 1 1 1 55m agl030519-vplxk-worker-us-east-1c 1 1 1 1 55m agl030519-vplxk-worker-us-east-1d 0 0 55m agl030519-vplxk-worker-us-east-1e 0 0 55m agl030519-vplxk-worker-us-east-1f 0 0 55m
When the new machine set is available, the
DESIREDandCURRENTvalues match. If the machine set is not available, wait a few minutes and run the command again.After the new machine set is available, check status of the machine and the node that it references:
$ oc describe machine <name> -n openshift-machine-api
For example:
$ oc describe machine agl030519-vplxk-infra-us-east-1a -n openshift-machine-api
Example output
status: addresses: - address: 10.0.133.18 type: InternalIP - address: "" type: ExternalDNS - address: ip-10-0-133-18.ec2.internal type: InternalDNS lastUpdated: "2019-05-03T10:38:17Z" nodeRef: kind: Node name: ip-10-0-133-18.ec2.internal uid: 71fb8d75-6d8f-11e9-9ff3-0e3f103c7cd8 providerStatus: apiVersion: awsproviderconfig.openshift.io/v1beta1 conditions: - lastProbeTime: "2019-05-03T10:34:31Z" lastTransitionTime: "2019-05-03T10:34:31Z" message: machine successfully created reason: MachineCreationSucceeded status: "True" type: MachineCreation instanceId: i-09ca0701454124294 instanceState: running kind: AWSMachineProviderStatusView the new node and confirm that the new node has the label that you specified:
$ oc get node <node_name> --show-labels
Review the command output and confirm that
node-role.kubernetes.io/<your_label>is in theLABELSlist.
Any change to a machine set is not applied to existing machines owned by the machine set. For example, labels edited or added to an existing machine set are not propagated to existing machines and nodes associated with the machine set.
