can i use a configmap created from an init container in the pod

Question

I am trying to \"pass\" a value from the init container to a container. Since values in a configmap are shared across the namespace, I figured I can use it for this purpose. Her

Answer 1

First of all, kubectl is a binary. It was downloaded in your machine before you could use the command. But, In your POD, the kubectl binary doesn't exist. So, you can't use kubectl command from a busybox image.

Furthermore, kubectl uses some credential that is saved in your machine (probably in ~/.kube path). So, If you try to use kubectl from inside an image, this will fail because of missing credentials.

For your scenario, I will suggest the same as @ccshih, use volume sharing. Here is the official doc about volume sharing between init-container and container.

The yaml that is used here is ,

apiVersion: v1
kind: Pod
metadata:
  name: init-demo
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80
    volumeMounts:
    - name: workdir
      mountPath: /usr/share/nginx/html
  # These containers are run during pod initialization
  initContainers:
  - name: install
    image: busybox
    command:
    - wget
    - "-O"
    - "/work-dir/index.html"
    - http://kubernetes.io
    volumeMounts:
    - name: workdir
      mountPath: "/work-dir"
  dnsPolicy: Default
  volumes:
  - name: workdir
    emptyDir: {}

Here init-containers saves a file in the volume and later the file was available in inside the container. Try the tutorial by yourself for better understanding.