Use Secret to Supply Environment Variables¶

Let's see how we can use Secret to supply environment variables to containers in a pod:

Step 1: Create a Secret¶

Let's create a Secret with data that contains the required environment variables:

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apiVersion: v1
kind: Secret
metadata:  
  name: my-secret
data:
  username: cmV5YW5zaA==
  password: bXlkYnBhc3N3b3Jk

Apply the manifest to create the Secret:

kubectl apply -f my-secret.yml

Step 2: Verify Secret¶

# List secrets
kubectl get secrets

# Describe the secret
kubectl describe secret my-secret

Step 3: Create Pods That Uses Environment Variables¶

Let's create pods that uses Secret to set environment variables for the container. We'll use a deployment to create pods:

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apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        envFrom:
        - secretRef:
            name: my-secret

Observe that we are using the keyword envFrom to supply a list of environment variables from the Secret my-secret.

Apply the manifest to create deployment:

kubectl apply -f my-deployment.yml

Step 4: Verify Deployment and Pods¶

# List deployments
kubectl get deployments

# List pods
kubectl get pods

Step 5: Verify Environment Variables¶

Start a shell session inside the container:

kubectl exec -it <pod-name> -- bash

List environment variables available to the container:

env

You'll see a list of environment variables available to the container. This includes both system-provided as well as user-provided environment variables.

Print values of the environment variables we set:

# Print value of the environment variable username
echo $username

# Print value of the environment variable password
echo $password

Clean Up¶

Assuming your folder structure looks like the one below:

|-- manifests
│   |-- my-secret.yml
│   |-- my-deployment.yml

Let's delete all the resources we created:

kubectl delete -f manifests/