external-scheduler.md

External scheduler

The external scheduler is the feature of the simulator to allow you to run any of your scheduler in the simulator instead of the default one.

Before diving into the description, you need to know debuggable scheduler.

connect your scheduler to the simulator

Let's connect your scheduler to the simulator.

First, you need to set externalSchedulerEnabled: true on the simulator config so that the scheduler, running in the simulator by default, won't get started.

Next, you need to connect your scheduler into the simulator's kube-apiserver via KubeSchedulerConfig:

kind: KubeSchedulerConfiguration
apiVersion: kubescheduler.config.k8s.io/v1
clientConnection:
  kubeconfig: ./path/to/kubeconfig.yaml

You can use this kubeconfig.yaml to communicate with the simulator's kube-apiserver.

The example external scheduler

You can see how the external scheduler can be set up with the sample debuggable scheduler implementation in ./sample/debuggable-scheduler.

prerequisite:

1. set externalSchedulerEnabled: true on the simulator config
2. run the simulator

cd sample/debuggable-scheduler
go run main.go --config scheduler.yaml

You'll see the simulator is working with the external scheduler.