Converting ConfigMap output into environment variables

All the examples we've seen so far are differing only in the source. The destination is always the same. No matter whether ConfigMap is created from a file, from a directory, from literal values, or from an environment file, it perpetually resulted in one or more files being injected into a container.

This time we'll try something different. We'll see how we can convert a ConfigMap into environment variables.

Let's take a look at a sample definition:

cat cm/alpine-env.yml  

The output is as follows.

apiVersion: v1 
kind: Pod 
metadata: 
  name: alpine-env 
spec: 
  containers: 
  - name: alpine 
    image: alpine 
    command: ["sleep"] 
    args: ["100000"] 
    env: 
    - name: something 
      valueFrom: 
        configMapKeyRef: 
          name: my-config 
          key: something...