🚀 Mastering ConfigMaps and Secrets in Kubernetes.

1️⃣ Task: Creating a ConfigMap

📝 Method 1: Using a YAML File

Create a file named configmap.yml and add the following content:

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config    # Name of the ConfigMap
data:
  APP_ENV: "production"  # Environment setting
  LOG_LEVEL: "debug"  # Logging level

📌 Explanation:

• apiVersion: v1 → Specifies the Kubernetes API version.

• kind: ConfigMap → Defines that this is a ConfigMap.

• metadata.name: my-config → Assigns a name to the ConfigMap.

• data → Stores key-value pairs used for configuration.

🔹 Apply the ConfigMap using the command:

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

📌 What this does:

• Applies the configmap.yml file to the specified namespace in Kubernetes.

📝 Method 2: Using the Command Line

If you don’t want to create a file, you can create a ConfigMap directly with this command:

kubectl create configmap my-config --from-literal=APP_ENV=production --from-literal=LOG_LEVEL=debug -n <namespace-name>

📌 Explanation:

• kubectl create configmap → Command to create a ConfigMap.

• my-config → Name of the ConfigMap.

• --from-literal=APP_ENV=production → Directly sets a key-value pair (APP_ENV=production).

• -n <namespace-name> → Specifies the namespace where the ConfigMap will be created.

🔎 Verify that the ConfigMap is created

kubectl get configmaps -n <namespace-name>

📌 Shows a list of ConfigMaps in the specified namespace.

kubectl describe configmap my-config -n <namespace-name>

📌 Displays details about the my-config ConfigMap.

---

2️⃣ Task: Using the ConfigMap in a Deployment

Modify your deployment.yml file to use the ConfigMap:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: nginx
          envFrom:
            - configMapRef:
                name: my-config  # Using the ConfigMap in the container

📌 Explanation:

• envFrom.configMapRef.name: my-config → Loads all key-value pairs from the ConfigMap into environment variables for the container.

🔹 Apply the updated Deployment

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

---

3️⃣ Task: Creating a Secret

📝 Method 1: Using a YAML File

Create a file named secret.yml:

apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
data:
  DB_PASSWORD: cGFzc3dvcmQ=  # Base64 encoded password (password)

📌 Encoding the Secret in Base64

Run the following command in your terminal to generate the Base64-encoded password:

echo -n "password" | base64

✅ Example Output:

cGFzc3dvcmQ=

📌 Explanation:

• kind: Secret → Defines that this is a Secret.

• type: Opaque → Specifies an arbitrary secret type.

• data.DB_PASSWORD: cGFzc3dvcmQ= → Base64-encoded value for password (password encoded in Base64).

🔹 Apply the Secret

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

📝 Method 2: Using the Command Line

kubectl create secret generic my-secret --from-literal=DB_PASSWORD=password -n <namespace-name>

📌 Explanation:

• kubectl create secret generic → Creates a generic Secret.

• my-secret → Name of the Secret.

• --from-literal=DB_PASSWORD=password → Adds a key-value pair with DB_PASSWORD=password.

• Kubernetes automatically encodes the value in Base64.

🔎 Verify that the Secret is created

kubectl get secrets -n <namespace-name>

📌 Lists all Secrets in the namespace.

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

📌 Shows detailed information about the Secret.

---

4️⃣ Task: Using the Secret in a Deployment

Modify your deployment.yml file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: nginx
          env:
            - name: DB_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: my-secret  # Using the Secret in the container
                  key: DB_PASSWORD

📌 Explanation:

• env.name: DB_PASSWORD → The environment variable inside the container.

• valueFrom.secretKeyRef.name: my-secret → Refers to the Kubernetes Secret named my-secret.

• valueFrom.secretKeyRef.key: DB_PASSWORD → Uses the DB_PASSWORD key from the Secret.

🔹 Apply the updated Deployment

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