Kubernetes Deployment Example

This exercise is all about Kubernetes deployment. Here we have go api service deployment step by step.

1. Create an api service using GoLang. Here we have main.go

2. Create a Dockerfile to dockerize the api service.

FROM golang
RUN mkdir app/ && cd app/
WORKDIR app/
COPY . .
RUN go build main.go
CMD ["./main"]
EXPOSE 8085

3. Buid an image using above docker file-

      docker build -t <imagename:tagname> .

4. Now before push this image to docker hub, we will do the tagging of image.

     docker tag <image-id> <reponame:tagname>

4. Push the image to your docker hub repository that you built using-

     docker push <reponame:tagname>

NOTE: Before pushing image to docker hub, you must login to docker using- docker login command

5. In this step we create 1 YAML file with name deployment.yaml

    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: api-deployment
    spec:
      replicas: 2
      selector:
        matchLabels:
          app: api-deployment
      template:
        metadata:
          labels:
            app: api-deployment
        spec:
          containers:
          - name: api-deployment
            image: sannidocker/myfirstrepository:api-image-v1.0
            ports:
             - containerPort: 80

6. Now create deployment using deployment.yaml. This will create a deployment with 2 replica pods.

     kubectl create -f deployment.yaml

7. To check the deployment and pods has created or not, we can use the below commands

     $ kubectl get deployments
       NAME             READY   UP-TO-DATE   AVAILABLE   AGE
       api-deployment   2/2     2            2           26m
       
     $ kubectl get pods
       NAME                              READY   STATUS    RESTARTS   AGE
       api-deployment-5f9c9cfb4d-7pdd7   1/1     Running   0          25m
       api-deployment-5f9c9cfb4d-nnrmp   1/1     Running   0          25m

Scale-up and Scale-down

Scale-up and scale-down can happen in two ways:

a. kubectl edit deployments <deployment-name>

• Here deployment-name is same as given in deployment.yaml file

b. kubectl scale <deployment-name> --replicas=<number-of-replica>

• Here deployment-name we can get using kubectl get all

  $ kubectl get all
  NAME                                  READY   STATUS    RESTARTS   AGE
  pod/api-deployment-869cb9548c-bxssz   1/1     Running   0          29m
  pod/api-deployment-869cb9548c-nvz82   1/1     Running   0          29m
  
  NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
  service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   11d
  
  NAME                             READY   UP-TO-DATE   AVAILABLE   AGE 
  deployment.apps/api-deployment   2/2     2            2           29m
  
  NAME                                        DESIRED   CURRENT   READY   AGE
  replicaset.apps/api-deployment-869cb9548c   2         2         2       29m