Deploying Apps on Kubernetes

Kubernetes is an open-source platform designed to automate deploying, scaling, and operating application containers. This lesson will guide you through the process of deploying applications on Kubernetes, covering key concepts, architecture, and practical steps.

• Basic understanding of Linux commands.
• Familiarity with containerization (Docker).
• Kubernetes installed on your machine or access to a Kubernetes cluster.

Kubernetes architecture consists of a master node and multiple worker nodes. The master node contains the control plane, while the worker nodes run the applications. Major components include:

• Control Plane: Manages the Kubernetes cluster.
• Node: A worker machine in Kubernetes.
• Pod: The smallest deployable unit in Kubernetes.
• Service: Exposes a set of pods as a network service.

4.1 Creating a Deployment

To deploy an application, you need to create a Deployment resource. Here’s a basic example of deploying an Nginx application:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Save the above YAML to a file named nginx-deployment.yaml and deploy it using:

kubectl apply -f nginx-deployment.yaml

4.2 Exposing the Application

After deploying, expose your application using a Service:

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: LoadBalancer
  ports:
    - port: 80
  selector:
    app: nginx

Apply the Service configuration with:

kubectl apply -f nginx-service.yaml

• Use versioned images for deployments.
• Define resource requests and limits for containers.
• Utilize health checks (liveness and readiness probes).
• Implement logging and monitoring solutions.
• Regularly update and patch your Kubernetes cluster.