slok/imagepull-controller-workshop

A Kubernetes controller workshop where we are creating a imagepullsecret-patcher controller

imagepull-controller-workshop

Versions

• workshop: First working version without some code for the workshop.
• v0.1.0: First working versions.
• v0.2.0: Optimized version for secret retrieval.

Agenda

Introduction

Problem

• Explain the problem to solve.
  • https://github.com/titansoft-pte-ltd/imagepullsecret-patcher
  • https://github.com/titansoft-pte-ltd/imagepullsecret-patcher/blob/master/main.go#L110
  • https://medium.com/titansoft-engineering/kubernetes-cluster-wide-access-to-private-container-registry-with-imagepullsecret-patcher-b8b8fb79f7e5

Concepts

• Controller Concepts
  • Edge and level trigger (1, 2)
  • Reconciliation
• Explain controller components (1, 2).
  • ListerWatcher
  • Handler
  • Queue (ID and cache) and workers.
  • Optimizations made on the Listers.

Implementation

Explanation

• What is Kooper and alternatives.
  • client-go.
  • Kubebuilder.
  • Operator framework.
• Explain project structure.

Implement

git clone git@github.com:slok/imagepull-controller-workshop.git && cd ./imagepull-controller-workshop
git checkout workshop

• Implement Retriever.
• Implement Handler.
• Test with local cluster using kind.

kind create cluster
kubectl apply -f ./tests/manual/secret.yaml
go run ./cmd/imagepull-controller-workshop/ -r default --secret-name test-imagepull-credentials --development

Optional homework

• Metrics.
• Unit testing.
• Secret.
  • Caching (Check v0.2.0).
  • Update on change (Secret controller).
• Service account.
  • Update on change instead of ensuring.

Further information

• Explain garbage collection.
  • Owner reference.
  • Finalizers.
• Creating an Operator.
  • kube-code-generator.
  • Create CRDs with clients.
    • Generate CRD (1, 2, 3)
    • Generate Client (1, 2)
• Production ready operator example (Bilrost).