ConfigMaps & Secret — Kubernetes

ConfigMaps and Secrets are used to store configuration data and secrets, respectively. ConfigMaps store configuration data as key-value pairs, while Secrets store sensitive data in an encrypted form.

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1. Create a ConfigMap for your Deployment
2. Create a ConfigMap for your Deployment using a file or the command line

apiVersion: v1
kind: ConfigMap
metadata:
  name: todo-app
data:
  name: django-todo-app
  application: todo-app
  protocol: TCP

Apply the changes using

kubectl apply -f configMap.yml

Update the deployment.yml file to include the ConfigMap

apiVersion: apps/v1
kind: Deployment
metadata:
  name: config-todo-app
  labels:
    app: todo
  namespace: todo-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: todo
  template:
    metadata:
      labels:
        app: todo
    spec:
      containers:
      - name: todo
        image: trainwithshubham/django-todo:latest
        ports:
        - containerPort: 8000
        env:
          - name: TODO_APP
            valueFrom:
              configMapKeyRef:
                name: todo-app
                key: application

Apply the updated deployment using the command:

First create a namespace after deploy the file

kubectl create namespace todo-app
kubectl apply -f deployment.yml <namespace-name>

Verify that the ConfigMap has been created by checking the status of the ConfigMaps in your Namespace.

The given command displays list of all ConfigMaps in your namespace

kubectl get configmaps -n todo-app

kubectl get pod -n todo-app

CreateContainerConfigError is an error that occurs when a Kubernetes container is transitioning from a pending state to a running state. It indicates the YAML configuration specified for a container in a pod is incorrect.

kubectl describe pod -n todo-app config-todo-app-84f646fbbc-fgh8l

A Secret is an object that contains a small amount of sensitive data such as a password, a token, or a key.

1. Create a Secret for your Deployment.
2. Create a Secret for your Deployment using a file or the command line.

apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
data:
  username: YWRtaW4=  # base64 encoded value for "admin"
  password: cGFzc3dvcmQyOTA2  # base64 encoded value for "password123"

In this example, we’re creating a Secret called my-secret with two keys: username and password. The values for these keys are base64-encoded, so that the encoded sensitive information can be stored as plain text in a file.

Apply the updated secret.yml file using the command

kubectl apply -f secret.yml -n <namespace-name>

Update the deployment.yaml file to include the Secret

apiVersion: apps/v1
kind: Deployment
metadata:
  name: config-demo
  labels:
    app: todo
  namespace: todo-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: todo
  template:
    metadata:
      labels:
        app: todo
    spec:
      containers:
      - name: todo
        image: trainwithshubham/django-todo:latest
        ports:
        - containerPort: 8000
        env:
          - name: env_secret
            valueFrom:
              secretKeyRef:
                name: my-secret
                key: password

Apply the updated deployment using the command

kubectl apply -f deployment.yml -n <namespace-name>

Verify that the Secret has been created by checking the status of the Secrets in your Namespace.

You can use the following command to verify that the Secret has been created

kubectl get secrets -n <namespace-name>

To view the details of a specific Secret

kubectl describe secret <secret-name> -n <namespace-name>

To see the key-value pairs of an environment variable in a ConfigMap inside a pod

kubectl get pod -n <namespace-name>

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

Thanks for reading