Whitebox Controller

Introducing Whitebox Controller.

Transcript

1. Whitebox Controller
   Extensible generic controller for Kubernetes
   Moto Ishizawa
   @summerwind Kubernetes Meetup Tokyo #18
   

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4. Implementing controller is hard…
   
   workqueue
   informers
   controller-tools
   controller-runtime
   reconciliation loop
   Golang
   controller-gen
   admission webhook
   owner reference
   vendor
   metav1
   apimachinery
   CustomResourceDefinition
   finalizer
   client-go corev1
   

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5. • Allow to make a controller without specific knowledges
   • Allow to implement a controller in familiar programming languages
   • Allow to validate new controller ideas more quickly
   Motivation
   

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6. Whitebox Controller
   • https://github.com/summerwind/whitebox-controller
   • Extensible generic controller for Kubernetes
   • It is possible to replace “reconciler” with any command or HTTP server
   • Very similar to Metacontroller, but executes command
   • Just like "Whitebox Switch" but it is for Kubernetes controller
   

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7. Extensible reconciler
   

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8. Whitebox Controller
   Managing resource state
   Exec hander
   Command
   {
   "object": {
   "apiVersion": "example.dev/v1alpha1",
   "kind": "Issue",
   "metadata": {
   "name": "example",
   "namespace": "default"
   },
   "spec": {
   "title": "Hello World!",
   "body": "This is an example."
   }
   }
   }
   Request
   
   (stdin)
   {
   "object": {
   "apiVersion": "example.dev/v1alpha1",
   "kind": "Issue",
   "metadata": {
   "name": "example",
   "namespace": "default"
   },
   "spec": {
   "title": "Hello World!",
   "body": "This is an example."
   },
   "status": {
   "url": "https://github.com/...",
   "creationTime": 12345
   }
   }
   }
   Response
   
   (stdout)
   

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9. Implementing controller in bash (1)
   controllers:
   - name: issue-controller
   resource:
   group: example.summerwind.dev
   version: v1alpha1
   kind: Issue
   reconciler:
   exec:
   command: ./reconcile.sh
   timeout: 60s
   debug: true
   Create the configuration file for Whitebox Controller.
   config.yaml
   

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10. Implementing controller in bash (2)
    #!/bin/bash
    # Read current state from stdio.
    state=$(cat -)
    # Do something based on the state.
    url=$(echo "${state}" | jq -r ".object.status.url|select (.!=null)")
    if [ "${url}" == "" ]; then
    url=$(create_issue "${state}")
    fi
    # Update state.
    updated_state=$(echo "${state}" | jq -r ".object.status.url = \"${url}\"")
    # Write updated state to stdout.
    echo "${updated_state}"
    Write your reconciler in bash.
    reconcile.sh
    

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11. Implementing controller in bash (3)
    $ whitebox-gen manifest -c config.yaml | kubectl apply -f -
    customresourcedefinition.apiextensions.k8s.io "issue.example.summerwind.dev" created
    Generate and apply CRDs.
    

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12. Implementing controller in bash (4)
    $ whitebox-controller -c config.yaml
    …
    {"level":"info","ts":1555560138.050401,"logger":"controller-
    runtime.controller","msg":"Starting workers","controller":"issue-controller","worker
    count”:1}
    Run whitebox-controller command.
    

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13. …and more!
    • Handler for finalizer
    • Handler for validation webhook
    • Handler for mutation webhook
    • Handler for injection webhook (Experimental resource injection endpoint)
    • Observer mode (“watch” only reconciler)
    • Periodic state sync
    

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14. Thank you!
    

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