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

If your various reasons, you don't want to use share volume. And you want to create a configmap or a secret, here is a solution.

First you need to use a docker image which contains kubectl : gcr.io/cloud-builders/kubectl:latest for example. (docker image which contains kubectl manage by Google).

Then this (init)container needs enough rights to create resource on Kubernetes cluster. Ok by default, kubernetes inject a token of default service account named : "default" in container, but I prefer to make more explicit, then add this line :

...
      initContainers:
        - # Already true by default but if use it, prefer to make it explicit
          automountServiceAccountToken: true
          name: artifactory-snapshot

And add "edit" role to "default" service account:

kubectl create rolebinding default-edit-rb --clusterrole=edit --serviceaccount=default:myapp --namespace=default

Then complete example :

apiVersion: batch/v1
kind: Job
metadata:
  name: installer-test
spec:
  template:
    spec:
      initContainers:
        - # Already true by default but if use it, prefer to make it explicit.
          automountServiceAccountToken: true
          name: artifactory-snapshot
          # You need to use docker image which contains kubectl
          image: gcr.io/cloud-builders/kubectl:latest
          command:
            - sh
            - -c
            # the "--dry-run -o yaml | kubectl apply -f -" is to make command idempotent
            - kubectl create configmap test-config --from-literal=artifactorySnapshotUrl=http://artifactory.com/some/url --dry-run -o yaml | kubectl apply -f -
      containers:
        - name: installer-test
          image: installer-test:latest
          env:
            - name: clusterId
              value: "some_cluster_id"
            - name: in_artifactoryUrl
              valueFrom:
                configMapKeyRef:
                  name: test-config
                  key: artifactorySnapshotUrl