Make the use of environment variables for handler more like core k8s about cli HOT 1 CLOSED

There is an alternative suggestion from @markfisher

Suggestion:

• Keep what we have for --env

  example:

  --env MY_VAR=my-value

  results in:

  - env:
    - name: MY_VAR
      value: my-value
  

• Change --env-from to accept secretKeyRef and configMapKeyRef as well as secretRef and configMapRef

  examples:

  --env-from MY_SECRET_VALUE=secretKeyRef:my-secret-name:key-in-secret

  results in:

  - env:
    - name: MY_SECRET_VALUE
      valueFrom:
        secretKeyRef:
          key: key-in-secret
          name: my-secret-name
  

  --env-from MY_CONFIG_MAP_VALUE=configMapKeyRef:my-config-map-name:key-in-config-map

  results in:

  - env:
    - name: MY_CONFIG_MAP_VALUE
      valueFrom:
        configMapKeyRef:
          key: key-in-config-map
          name: my-config-map-name
  

  --env-from configMapRef:my-config-map-name

  results in:

  - envFrom:
    - configMapRef:
        name: my-config-map-name
  

  --env-from prefix_:secretRef:my-secret-name

  results in:

  - envFrom:
    - prefix: prefix_
      secretRef:
        name: my-secret-name
  

from cli.