Friends,

I am learning here and trying to run a pod with an init container which checks if the DNS of the service of my mysql pod resolves. Both pods are being deployed with helm (Version:v3.4.1) charts created by me in minikube (version: v1.15.0).

The problem is that the init container tries for about five minutes until it finally resolves the DNS. It always works after 4 to 5 minutes but never before that, no matter for how long the mysql pod is running and the mysql service exists. Does anyone know how this is happening?

One interesting thing is that if I pass the clusterIP instead of the the DNS, it resolves immediately and it also resolves immediately if I passe the full domain name like this: mysql.default.svc.cluster.local.

Here is the conde of my init container:

 initContainers:
    - name: {{ .Values.initContainers.name }}
      image: {{ .Values.initContainers.image }}
      command: ['sh', '-c', 'until nslookup mysql; do echo waiting for mysql; sleep 2; done;']

Here is the service of the mysql deployment:

apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
spec:
  ports:
  - protocol: TCP
    port: 3306
    targetPort: 3306
  selector:
    app: mysql
  type: ClusterIP

And the deployment of the mysql:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
  labels: 
    app: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:8.0
        envFrom:
        - configMapRef:
            name: mysql
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-storage
          mountPath: /var/lib/mysql
          subPath: mysql
      volumes:
      - name: mysql-storage
        persistentVolumeClaim:
          claimName: pvc-mysql