How To Provide ENV Variable From K8s To A Python App During The Docker Run

I have a docker file in which I am hardcoding the env variables for now as it gets injected in the app during the build process. Now, I want to inject those during the runtime when

Solution 1:

First Create k8s configmap or k8s secret(better for sensitive data) in your cluster. Then read these values in k8s deployment yaml as env variables for pod.

official Docs: https://kubernetes.io/docs/concepts/configuration/secret/

Eg. Create secret yaml

apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
    username: "abc-user"
    password: "pwd-here"

Deployment yaml

apiVersion: v1
kind: Pod
metadata:
  name: secret-env-pod
spec:
  containers:
  - name: mycontainer
    image: redis
    env:
      - name: DB_USERNAME
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: username
      - name: DB_PASSWORD
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: password
  restartPolicy: Never

Solution 2:

You can pass env variables to k8s pod with pod spec field: env.

Look a the following example from k8s docs:

apiVersion: v1
kind: Pod
metadata:
  name: envar-demo
  labels:
    purpose: demonstrate-envars
spec:
  containers:
  - name: envar-demo-container
    image: gcr.io/google-samples/node-hello:1.0
    env:
    - name: DEMO_GREETING
      value: "Hello from the environment"
    - name: DEMO_FAREWELL
      value: "Such a sweet sorrow"

Also take a look at k8s documentaion for more information:

• k8s api spec reference
• defining environment variables
• using secrets as environment variables