admission_controller_practice

• 개요
• 준비
• 실행 방법
  • self signed 인증서 생성
  • admission controller를 실행할 golang pod 생성
  • webhook 생성
• admission controller 테스트
• 참고자료

개요

kubernetes adminssion controller 연습

준비

• kind 쿠버네티스 클러스터 생성

# 생성
make up

# 삭제
make down

실행 방법

self signed 인증서 생성

mkdir certs

openssl req -x509 -newkey rsa:4096 -nodes -out certs/ca.crt -keyout certs/ca.key -days 365 -config ./cert.cnf -extensions req_ext

kubectl create secret tls webhook-certs --cert=certs/ca.crt --key=certs/ca.key --namespace=default

admission controller를 실행할 golang pod 생성

• golang 컨테이너가 있는 pod생성

kubectl apply -f ./manifests/golang-deployment.yaml
kubectl apply -f ./manifests/service.yaml

• golang pod 쉘 접속

kubectl get pod -n default
kubectl exec -it {pod 이름} -- /bin/bash

• go 모듈 초기화와 외부모듈 다운로드

go mod init github.com/opsarena/admission-controller
go get k8s.io/api/admission/v1
go get k8s.io/apimachinery/pkg/apis/meta/v1
go get k8s.io/api/core/v1

• main.go 파일 생성: main.go파일을 pod안에 복사

• main.go 실행

go run main.go

webhook 생성

• validate webhook

CA_BUNDLE=$(cat ./certs/ca.crt | base64 | tr -d '\n')
sed -e 's@${CA_BUNDLE}@'"$CA_BUNDLE"'@g' < ./manifests/validation-webhook.yaml | kubectl apply -f -

• mutate webhook

CA_BUNDLE=$(cat ./certs/ca.crt | base64 | tr -d '\n')
sed -e 's@${CA_BUNDLE}@'"$CA_BUNDLE"'@g' < ./manifests/mutate-webhook.yaml | kubectl apply -f -

admission controller 테스트

• buysbox 생성 후 admission controller pod로그 확인

kubectl apply -f ./manifests/busybox-pod.yaml

참고자료

• https://github.com/GoesToEleven/golang-web-dev
• https://koras02.tistory.com/236
• https://dev.to/ashokan/simple-validation-webhook-with-python-5bof
• https://github.com/slackhq/simple-kubernetes-webhook/blob/main/pkg/admission/admission.go#L83
• https://sphong0417.tistory.com/54