What is Deployment in k8s

A Deployment provides a configuration for updates for Pods and ReplicaSets.

Task-1:

Create one Deployment file to deploy a sample todo-app on K8s using the "Auto-healing" and "Auto-Scaling" features.

• First, we have to make a deployment Yaml file. We can use deployment.yaml file provided

    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: todo-app
      labels:
        app: todo
    spec:
      replicas: 2
      selector:
        matchLabels:
          app: todo
      template:
        metadata:
          labels:
            app: todo
        spec:
          containers:
          - name: todo
            image: rishikeshops/todo-app
            ports:
            - containerPort: 3000
  

  or we can build an image first with docker and push the image in docker Hub and write a new YAML file.

  Let's create it from scratch.

  • Fork the repo from GitHub

    https://github.com/sri766/django-todo-cicd

    

  • Clone it to the local system

    git clone <repo_url>

  • build the image with the docker

      docker build -t <docker_hub_username>/<name>:<tag> .
    
      #eg: docker build -t sri766/django-todo:latest .
      #note: name must be in lower_case
    

    

  • now run the docker run command to up the container

      docker run -d -p 8000:8000 sri766/django-todo:latest
    

    

  • and push the image to DockerHub docker push <image_name>:<tag>

    

  • now, cd to k8s, and check the image to your repo image. eg: sri766/django-todo:latest

  • now we have to create a pod for eg: (we don't have to create another pod.yaml file it already created in k8s folder). just run kubectl apply -f pod.yaml

    

    

      #template to create a pod 
      apiVersion: v1
      kind: Pod
      metadata:
        name: nginx
      spec:
        containers:
        - name: nginx
          image: nginx:1.14.2
          ports:
          - containerPort: 80
    

    Now, we have to create a development. Its main feature is auto-scaling and auto-healing.

    • just write kubectl apply -f development.yaml you will see 3 containers running simultaneously.

    • we can scale it with replica set

      kubectl scale --replicas=3 deployment/my-deployment

      

    • auto-healing: if you delete a pod deployment create a new pod automatically. As you can see in this example:

      

Thanks !! for your patient reading 💕

Happy learning !