Update k8s deployment on a configmap change

原文链接

kubectl v1.15 now provides a rollout restart sub-command that allows you to restart Pods in a Deployment - taking into account your surge/unavailability config - and thus have them pick up changes to a referenced ConfigMap, Secret or similar. It’s worth noting that you can use this with clusters older than v1.15, as it’s implemented in the client.

Example usage: kubectl rollout restart deploy/admission-control to restart a specific deployment. Easy as that!

there are certainly cases where we want to:

Update a ConfigMap
Have our Deployment reference that specific ConfigMap version (in a version-control & CI friendly way)
Rollout a new revision of our Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo-deployment
  labels:
    app: config-demo-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: config-demo-app
  template:
    metadata:
      labels:
        app: config-demo-app
    annotations:
      # The field we'll use to couple our ConfigMap and Deployment
      configHash: ""
    spec:
      containers:
        - name: config-demo-app
          image: gcr.io/optimum-rock-145719/config-demo-app
          ports:
            - containerPort: 80
          envFrom:
            # The ConfigMap we want to use
            - configMapRef:
                name: demo-config
          # Extra-curricular: We can make the hash of our ConfigMap available at a
          # (e.g.) debug endpoint via a fieldRef
          env:
            - name: CONFIG_HASH
              valueFrom:
                fieldRef:
                  fieldPath: spec.template.metadata.annotations.configHash

采用confighash的方式

这样就可以自动rollout restart

# Invoke as hash-deploy-config deployment.yaml configHash myConfigMap
hash-deploy-config() {
  yq w $1 spec.template.metadata.annotations.$2 \
  $(kubectl get cm/$3 -oyaml | sha256sum)
}

We can now re-deploy our Deployment, and because our spec.template changed, Kubernetes will detect it as a change and re-create our Pods.

以此为原理的工程

repo