Container logging architecture in Kubernetes - Mini Project: Build & Apply

Container Logging Architecture in Kubernetes

📖 Scenario: You are working as a DevOps engineer managing a Kubernetes cluster. You want to set up a simple container logging architecture to collect logs from your application pods and store them centrally for easy access and troubleshooting.

🎯 Goal: Build a basic container logging setup in Kubernetes by creating a pod with a container that writes logs, configure a log path variable, collect logs using a sidecar container, and finally display the collected logs.

📋 What You'll Learn

Create a pod manifest with a main container that writes logs to a file

Add a configuration variable for the log file path

Add a sidecar container that reads the log file and outputs logs

Display the logs collected by the sidecar container

💡 Why This Matters

🌍 Real World

Centralized logging helps DevOps teams monitor and troubleshoot applications running in Kubernetes clusters efficiently.

💼 Career

Understanding container logging architecture is essential for roles like DevOps engineer, site reliability engineer, and cloud administrator.

1

Create a pod manifest with a main container that writes logs

Create a Kubernetes pod manifest named logging-pod.yaml with a pod called logger. It should have one container named app using the image busybox. The container should run the command sh -c "while true; do echo 'Log entry' >> /var/log/app.log; sleep 5; done" to write logs continuously to /var/log/app.log. Use an emptyDir volume named log-volume mounted at /var/log.

Kubernetes

# Create the pod manifest with the specified container and volume
# Your code here

Need a hint?

Use emptyDir volume to share logs inside the pod. The app container writes logs to /var/log/app.log.

2

Add a configuration variable for the log file path

Add an environment variable named LOG_PATH with the value /var/log/app.log to the app container in the logging-pod.yaml manifest.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: logger
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "while true; do echo 'Log entry' >> /var/log/app.log; sleep 5; done"]
    volumeMounts:
    - name: log-volume
      mountPath: /var/log
    # Add environment variable LOG_PATH here
    env:
    # Your code here
  volumes:
  - name: log-volume
    emptyDir: {}

Need a hint?

Use the env field inside the app container to add the LOG_PATH variable.

3

Add a sidecar container to read and output logs

Add a second container named log-reader to the pod. Use the image busybox. It should mount the same log-volume at /var/log and run the command sh -c "tail -f /var/log/app.log" to continuously output the logs.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: logger
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "while true; do echo 'Log entry' >> /var/log/app.log; sleep 5; done"]
    volumeMounts:
    - name: log-volume
      mountPath: /var/log
    env:
    - name: LOG_PATH
      value: "/var/log/app.log"
  # Add the log-reader container below
  - name: log-reader
    # Your code here
  volumes:
  - name: log-volume
    emptyDir: {}

Need a hint?

The log-reader container shares the log-volume and tails the log file to output logs.

4

Display the logs collected by the sidecar container

Run the command kubectl logs logger -c log-reader to display the logs output by the log-reader container.

Kubernetes

# Run the kubectl command below to show logs from the log-reader container
# Your code here

Need a hint?

This command fetches logs from the log-reader container inside the logger pod.