Custom Scheduling
- Overview
- Deploying the Scheduler

Custom Scheduling

You are viewing documentation for a release that is no longer supported. The latest supported version of version 3 is [3.11]. For the most recent version 4, see [4]

Overview

You can run multiple, custom schedulers alongside the default scheduler and configure which scheduler to use for each pods.

To schedule a given pod using a specific scheduler, specify the name of the scheduler in that pod specification.

Deploying the Scheduler

The steps below are the general process for deploying a scheduler into your cluster.

Information on how to create/deploy a scheduler is outside the scope of this document. For an example, see plugin/pkg/scheduler in the Kubernetes source directory.

Create or edit a pod configuration and specify the name of the scheduler with the schedulerName parameter. The name must be unique.

Sample pod specification with scheduler
```
apiVersion: v1
kind: Pod
metadata:
  name: custom-scheduler
  labels:
    name: multischeduler-example
spec:
  schedulerName: custom-scheduler (1)
  containers:
  - name: pod-with-second-annotation-container
    image: docker.io/ocpqe/hello-pod
```
1 The name of the scheduler to use. When no scheduler name is supplied, the pod is automatically scheduled using the default scheduler.
Run the following command to create the pod:
```
$ oc create -f scheduler.yaml
```
Run the following command to check that the pod was created with the custom scheduler:
```
$ oc get pod custom-scheduler -o yaml
```

Run the following command to check the status of the pod:

$ oc get pod

The pod should not be running.

NAME                READY     STATUS    RESTARTS   AGE
custom-scheduler    0/1       Pending    0         2m

Deploy the custom scheduler.

Run the following command to check the status of the pod:

$ oc get pod

The pod should be running.

NAME                READY     STATUS    RESTARTS   AGE
custom-scheduler    1/1       Running    0         4m

Run the following command to check that the scheduler was used:

$ oc describe pod custom-scheduler

The name of the scheduler is listed, as shown in the following truncated output:

[...]
Events:
  FirstSeen  LastSeen  Count  From              SubObjectPath  Type       Reason Message
  ---------  --------  -----  ----              -------------  --------   ------ -------
  1m         1m        1      my-scheduler      Normal         Scheduled  Successfully assigned custom-scheduler to <$node1>
[...]