Load env variables from ConfigMaps and Secrets upon Pod boot

Apr 21, 2017

One of the coolest stuff I’ve picked up just today is that you can keep environment variables that you want to be loaded into every deployment pod in a neatly configured ConfigMap or Secret which gets injected back into the Pod during deploys.

Lets say you have a Secret that looks like:

apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
  username: YWRtaW4=
  password: MWYyZDFlMmU2N2Rm

And you want username and password to be easily accessible in ENV['username'] and ENV['password'] on your application pods, all you need is a envFrom within your TemplateSpec

ie.

apiVersion: extension/v1beta1
kind: Deployment
spec:
  replicas:1
  template:
    spec:
      containers:
        - name: test-container
          image: gcr.io/google_containers/busybox
          command: [ "/bin/sh", "-c", "env" ]
          envFrom:
            - secretRef:
                name: mysecret

Because envFrom expects an array, you can do multiple references like:

envFrom:
  - secretRef:
      name: hello
  - configMapRef:
      name: hello2
  - configMapRef:
      name: hello3

This will take all the data keys from the 2 ConfigMaps and 1 Secret and load it into your pod.

References

Kubernetes - Configmap