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Certified Kubernetes Application Developer (CKAD)

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The Certified Kubernetes Application Developer (CKAD) certification is designed for Kubernetes practitioners who want to demonstrate their ability to design, build, and deploy cloud-native applications for Kubernetes. This module will guide you through the key areas of the CKAD exam, providing you with the knowledge and skills needed to pass the certification.

Overview of CKAD Exam

Exam Details

  • Duration: 2 hours
  • Format: Performance-based, hands-on tasks
  • Passing Score: 66%
  • Prerequisites: Basic understanding of Kubernetes concepts and experience with kubectl

Exam Domains

The CKAD exam covers the following domains:

  1. Core Concepts (13%)
  2. Configuration (18%)
  3. Multi-Container Pods (10%)
  4. Observability (18%)
  5. Pod Design (20%)
  6. Services & Networking (13%)
  7. State Persistence (8%)

Core Concepts

Key Topics

  • Kubernetes API Primitives: Understand the basic Kubernetes objects such as Pods, Deployments, and Services.
  • Cluster Architecture: Familiarize yourself with the components of a Kubernetes cluster.

Practical Example

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: my-container
    image: nginx

Explanation:

  • apiVersion: Specifies the API version.
  • kind: Defines the type of Kubernetes object.
  • metadata: Contains metadata about the object, such as its name.
  • spec: Describes the desired state of the object.
  • containers: Lists the containers within the Pod.

Configuration

Key Topics

  • ConfigMaps and Secrets: Manage configuration data and sensitive information.
  • Environment Variables: Use environment variables to configure applications.

Practical Example

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  key1: value1
  key2: value2

Explanation:

  • data: Contains key-value pairs of configuration data.

Multi-Container Pods

Key Topics

  • Sidecar Containers: Use sidecar containers to enhance the functionality of the main container.
  • Init Containers: Use init containers to perform initialization tasks before the main container starts.

Practical Example

apiVersion: v1
kind: Pod
metadata:
  name: multi-container-pod
spec:
  containers:
  - name: main-container
    image: nginx
  - name: sidecar-container
    image: busybox
    command: ["sh", "-c", "echo Hello from the sidecar"]

Explanation:

  • containers: Lists multiple containers within the Pod.

Observability

Key Topics

  • Probes: Use liveness, readiness, and startup probes to monitor container health.
  • Logging and Monitoring: Implement logging and monitoring for applications.

Practical Example

apiVersion: v1
kind: Pod
metadata:
  name: pod-with-probes
spec:
  containers:
  - name: my-container
    image: nginx
    livenessProbe:
      httpGet:
        path: /healthz
        port: 80
      initialDelaySeconds: 3
      periodSeconds: 3

Explanation:

  • livenessProbe: Defines a probe to check if the container is alive.

Pod Design

Key Topics

  • Labels and Selectors: Use labels and selectors to organize and manage Kubernetes objects.
  • Annotations: Use annotations to attach metadata to objects.

Practical Example

apiVersion: v1
kind: Pod
metadata:
  name: labeled-pod
  labels:
    app: my-app
spec:
  containers:
  - name: my-container
    image: nginx

Explanation:

  • labels: Attach key-value pairs to the Pod for identification.

Services & Networking

Key Topics

  • Service Types: Understand different service types (ClusterIP, NodePort, LoadBalancer).
  • Network Policies: Implement network policies to control traffic flow.

Practical Example

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP

Explanation:

  • selector: Selects the Pods to expose.
  • ports: Defines the ports for the service.

State Persistence

Key Topics

  • Persistent Volumes (PVs) and Persistent Volume Claims (PVCs): Manage storage for stateful applications.
  • Storage Classes: Use storage classes to define different types of storage.

Practical Example

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

Explanation:

  • accessModes: Defines how the volume can be accessed.
  • resources: Specifies the storage request.

Practical Exercises

Exercise 1: Create a Pod with a ConfigMap

  1. Create a ConfigMap named app-config with the following data: 
    apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  config.json: |
    {
      "key": "value"
    }
  2. Create a Pod named app-pod that uses the app-config ConfigMap.

Solution:

apiVersion: v1
kind: Pod
metadata:
  name: app-pod
spec:
  containers:
  - name: app-container
    image: busybox
    command: ["sh", "-c", "cat /etc/config/config.json"]
    volumeMounts:
    - name: config-volume
      mountPath: /etc/config
  volumes:
  - name: config-volume
    configMap:
      name: app-config

Exercise 2: Implement a Liveness Probe

  1. Create a Pod named probe-pod with a container that uses the nginx image.
  2. Add a liveness probe that checks the /healthz endpoint on port 80.

Solution:

apiVersion: v1
kind: Pod
metadata:
  name: probe-pod
spec:
  containers:
  - name: nginx-container
    image: nginx
    livenessProbe:
      httpGet:
        path: /healthz
        port: 80
      initialDelaySeconds: 3
      periodSeconds: 3

Conclusion

In this module, you have learned about the key areas covered in the CKAD exam, including core concepts, configuration, multi-container pods, observability, pod design, services and networking, and state persistence. By understanding these topics and practicing the provided exercises, you will be well-prepared to take the CKAD certification exam. Good luck!

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Kubernetes Course

Module 1: Introduction to Kubernetes

Module 2: Core Kubernetes Components

Module 3: Configuration and Secrets Management

Module 4: Networking in Kubernetes

Module 5: Storage in Kubernetes

Module 6: Advanced Kubernetes Concepts

Module 7: Monitoring and Logging

Module 8: Security in Kubernetes

Module 9: Scaling and Performance

Module 10: Kubernetes Ecosystem and Tools

Module 11: Case Studies and Real-World Applications

Module 12: Preparing for Kubernetes Certification

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