scheduling-framework-regex-plugin

README

Regex Scheduling Plugin implemented as a Scheduler Framework Plugin in Golang

This is an implementation which uses the Scheduling Framework implementation in Go.

v1

This is the basic version of the plugin. It is triggered by the Filter method, receiving both the pod and node as parameters.

The plugin checks for the scheduler.wasmkwokwizardry.io/regex annotation on the pod, using its value as a regex pattern to match against the node name. If the node name does not match the specified regex, the plugin returns an Unschedulable status to indicate that the node is not a suitable candidate for scheduling the pod.

The code can be found under the v1 directory.

How to run

1. Go to the Simulator project by running cd kube-scheduler-simulator/simulator
2. Add the new plugin as a dependency by running go get github.com/wasmkwokwizardry/kubecon-na-2024/scheduling-framework-regex-plugin
3. Open this file and import the following module: regex "github.com/wasmkwokwizardry/kubecon-na-2024/scheduling-framework-regex-plugin/v1/plugin"
4. Add the Regex Scheduling plugin to the out-of-tree registry:

   var outOfTreeRegistries = runtime.Registry{
       regex.Name: regex.New,
   }
   

5. Go back to the project root and run the Simulator by running make start-simulator.
6. Open the Simulator at http://localhost:3000 in your browser.
7. Click the cog icon in the upper-left corner to open the Scheduler configuration and edit the plugins field so it contains the following:

   multiPoint:
     enabled:  
     - name: RegexScheduling
   

8. Create a Node with a default name and additional two Nodes named kubecon-1 and kubecon-2
9. Create a Pod with an annotation scheduler.wasmkwokwizardry.io/regex: 'kubecon-.*'

   annotations:
     scheduler.wasmkwokwizardry.io/regex: 'kubecon-.*'
   

10. Create a Pod with an annotation for a non-existing Node Group and observe result:

    annotations:
      scheduler.wasmkwokwizardry.io/regex: 'cncf-.*'
    

v2

This version adds a PreFilter step where it compiles the regex pattern and caches it for later use in the Filter step. This avoids recompiling the regex pattern in each invocation of the Filter method for a given pod and available nodes.

The code can be found under the v2 directory.

How to run

1. Open the file simulator/scheduler/config/plugin.go and edit import from the previous version: regex "github.com/wasmkwokwizardry/kubecon-na-2024/scheduling-framework-regex-plugin/v2/plugin"
2. Restart the Simulator by running make start-simulator from the project root.
3. Open the Simulator at http://localhost:3000 in your browser.
4. Click the cog icon in the upper-left corner to open the Scheduler configuration and edit the plugins field so it contains the following:

   multiPoint:
     enabled:  
     - name: RegexScheduling
   

5. Profit!