DaemonSets for per-node workloads in Kubernetes - Mini Project: Build & Apply

DaemonSets for per-node workloads

📖 Scenario: You are managing a Kubernetes cluster where you need to run a monitoring agent on every node. This agent collects system metrics and sends them to a central dashboard. To ensure the agent runs on all current and future nodes automatically, you will use a DaemonSet.

🎯 Goal: Create a Kubernetes DaemonSet manifest that deploys a monitoring agent container on every node in the cluster.

📋 What You'll Learn

Create a DaemonSet manifest named monitor-agent in the default namespace

Use the container image busybox with the command ['sh', '-c', 'while true; do echo Monitoring; sleep 30; done']

Set the container name to monitor-agent-container

Ensure the DaemonSet runs one pod per node

Add a label app: monitor-agent to the pod template metadata

💡 Why This Matters

🌍 Real World

DaemonSets are used to deploy system-level agents like monitoring, logging, or security tools on every node automatically.

💼 Career

Understanding DaemonSets is essential for Kubernetes administrators and DevOps engineers to manage node-level workloads efficiently.

1

Create the DaemonSet skeleton

Create a YAML manifest for a DaemonSet named monitor-agent in the default namespace. Include the apiVersion, kind, metadata with the name and namespace, and an empty spec section.

Kubernetes

# Your code here

Need a hint?

Start with the basic structure of a DaemonSet manifest including apiVersion, kind, and metadata.

2

Add the pod template with labels and container

Inside the spec section, add a selector with matchLabels set to app: monitor-agent. Then add a template section with metadata labels app: monitor-agent and a spec that defines one container named monitor-agent-container using the image busybox.

Kubernetes

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: monitor-agent
  namespace: default
spec:
  # Add selector and template with labels and container here

Need a hint?

Remember the selector.matchLabels must match the pod template labels exactly.

3

Add the container command to run the monitoring loop

In the container spec, add the command field with the value ['sh', '-c', 'while true; do echo Monitoring; sleep 30; done'] to keep the container running and printing 'Monitoring' every 30 seconds.

Kubernetes

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: monitor-agent
  namespace: default
spec:
  selector:
    matchLabels:
      app: monitor-agent
  template:
    metadata:
      labels:
        app: monitor-agent
    spec:
      containers:
      - name: monitor-agent-container
        image: busybox
        # Add the command to run the monitoring loop here

Need a hint?

The command field overrides the default container command to run your monitoring loop.

4

Display the DaemonSet manifest

Print the complete DaemonSet YAML manifest to the console.

Kubernetes

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: monitor-agent
  namespace: default
spec:
  selector:
    matchLabels:
      app: monitor-agent
  template:
    metadata:
      labels:
        app: monitor-agent
    spec:
      containers:
      - name: monitor-agent-container
        image: busybox
        command: ['sh', '-c', 'while true; do echo Monitoring; sleep 30; done']

# Print the manifest below

Need a hint?

Use a print statement to output the entire YAML manifest as a string.