Multi-container Pods concept in Kubernetes - Mini Project: Build & Apply

Multi-container Pods concept

📖 Scenario: You are working on a Kubernetes cluster for a simple web application. This application needs two containers running together in the same Pod: one container serves the web content, and the other container logs the web server activity.

🎯 Goal: Create a Kubernetes Pod manifest with two containers inside it. One container runs the nginx web server, and the other container runs a simple busybox container that logs messages to a shared volume.

📋 What You'll Learn

Create a Pod manifest named multi-container-pod.yaml.

Define two containers inside the Pod: web-server using the nginx image and logger using the busybox image.

Add a shared emptyDir volume named shared-logs mounted at /var/log in both containers.

The logger container should run the command sh -c 'while true; do echo Logging... >> /var/log/log.txt; sleep 5; done' to simulate logging.

The web-server container should expose port 80.

💡 Why This Matters

🌍 Real World

Multi-container Pods are used when containers need to work closely together, like a web server and a helper container for logging or data processing.

💼 Career

Understanding multi-container Pods is essential for Kubernetes administrators and DevOps engineers to design efficient and maintainable applications.

1

Create the basic Pod manifest with metadata

Create a YAML file named multi-container-pod.yaml with a Pod manifest. Add apiVersion: v1, kind: Pod, and metadata with name: multi-container-pod.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  # Your code here

Need a hint?

Start by defining the Pod with its API version, kind, and give it a name under metadata.

2

Add two containers with images and ports

Under spec, add two containers: one named web-server using image nginx exposing port 80, and another named logger using image busybox. Do not add commands or volumes yet.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: multi-container-pod
spec:
  containers:
  # Your code here

Need a hint?

Remember to indent containers properly under spec and list each container with its name and image.

3

Add shared volume and mount paths, and logger command

Add an emptyDir volume named shared-logs under spec.volumes. Mount this volume at /var/log in both containers. Add the command sh -c 'while true; do echo Logging... >> /var/log/log.txt; sleep 5; done' to the logger container.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: multi-container-pod
spec:
  containers:
  - name: web-server
    image: nginx
    ports:
    - containerPort: 80
  - name: logger
    image: busybox
  # Your code here

Need a hint?

Use emptyDir: {} to create a shared volume. Mount it in both containers at /var/log. Add the command as a list of strings in the logger container.

4

Display the final Pod manifest

Print the complete content of multi-container-pod.yaml to verify your multi-container Pod manifest.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: multi-container-pod
spec:
  containers:
  - name: web-server
    image: nginx
    ports:
    - containerPort: 80
    volumeMounts:
    - name: shared-logs
      mountPath: /var/log
  - name: logger
    image: busybox
    command:
    - sh
    - -c
    - while true; do echo Logging... >> /var/log/log.txt; sleep 5; done
    volumeMounts:
    - name: shared-logs
      mountPath: /var/log
  volumes:
  - name: shared-logs
    emptyDir: {}

# Print the Pod manifest below

Need a hint?

Use print(open('multi-container-pod.yaml').read()) to display the file content if running locally, or simply output the YAML content as a string.