alpine-envsubst

Docker image based on alpine to use envsubst (part of the gettext package) to substitute environmen variables in init containers.

Usage

The entrypoint expects two parameters which are the source file and the target file where the rendered output is stored.

Example:

docker run -v $(pwd)/config:/config mee /config/config.template /config/config.rendered

k8s example with initContainer

initContainers:
  - name: render-config
    image: ghcr.io/makandra/alpine-envsubst:v1.0.0
    args: ["/source/config.json", "/rendered/config.json"]
    env:
      - name: SOMEENV
        valueFrom:
          secretKeyRef:
            name: some_secret
            key: some_key
    volumeMounts:
    - name: template-config
      mountPath: /source/config.json
      subPath: config.json
    - mountPath: /rendered
      name: rendered-configuration
volumes:
- name: template-config
  configMap:
    name: template-config
    items:
    - key: config.json
      path: config.json
- name: rendered-configuration
  emptyDir:
    sizeLimit: 5Mi

The rendered-configuration volume can then be mounted in the containers requiring the configuration.