(Day 36) Task : Kubernetes ConfigMaps & Secrets :-

In a modern DevOps environment, configuration management and secrets handling are essential for secure and scalable application deployments. Kubernetes offers two native mechanisms for managing configuration data: ConfigMaps and Secrets. These are designed to decouple configuration from the application code and Docker images, thus enabling smoother deployments across different environments.

Why Use ConfigMaps and Secrets?

When deploying applications across different environments (development, QA, production), configuration files and environment-specific values often differ. Traditionally, updating these values meant:

1. Editing source code

2. Committing changes

3. Rebuilding the Docker image

4. Redeploying the application

This approach is time-consuming and error-prone. Kubernetes ConfigMaps and Secrets solve this by decoupling configuration from the container image, enabling the same image to be used in different environments by simply injecting different configurations.

ConfigMap: Managing Non-Sensitive Configuration :

What is a ConfigMap?

A ConfigMap is a Kubernetes object used to store non-sensitive, unencrypted configuration data in key-value pairs or configuration files.

Use Cases :

• Application environment variables

• System properties or feature toggles

• Entire configuration files (e.g., .env, .properties)

How to Use ConfigMaps :-

1. As Environment Variables :

When you use a ConfigMap as environment variables, the key-value pairs inside the ConfigMap are injected into the container's environment, just like how you’d use export in a shell.

apiVersion: v1
kind: Pod
metadata:
  name: config-env-demo
spec:
  containers:
    - name: app-container
      image: my-app
      envFrom:
        - configMapRef:
            name: app-config

2. As Volumes (Mounting Config Files) :

When you mount a ConfigMap as a volume, Kubernetes creates actual files inside the container's filesystem, where each key becomes a file, and the file content is the value.

apiVersion: v1
kind: Pod
metadata:
  name: config-volume-demo
spec:
  containers:
    - name: app-container
      image: my-app
      volumeMounts:
        - name: config-volume
          mountPath: "/etc/config"
  volumes:
    - name: config-volume
      configMap:
        name: app-config

How to Create a ConfigMap :

From Literal Key-Value Pairs

kubectl create configmap app-config --from-literal=MODE=dev --from-literal=LOG_LEVEL=info

From a File

kubectl create configmap app-config --from-file=config.properties

Secrets: Safeguarding Sensitive Information

What is a Secret?

A Secret is a Kubernetes object designed to store sensitive information, such as:

• Database passwords

• API keys

• Tokens

Unlike ConfigMaps, Secrets are base64 encoded and optionally encrypted when stored in etcd. They are mounted in-memory using tmpfs so that they are not written to disk.

Properties of Secrets

• Namespace-scoped objects

• Accessible via env vars or volumes

• Stored in-memory (tmpfs) in the pod

• Size limit: 1 MB