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In this guide, you’ll learn how to create a Kubernetes Deployment manifest to deploy your Docker image on Google Kubernetes Engine (GKE). We’ll cover:
  1. Creating a Git branch
  2. Writing the Deployment manifest
  3. Understanding each field in the YAML
  4. Next steps for automated deployment

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Prerequisites

  • A working GKE cluster
  • kubectl configured to talk to your GKE cluster
  • Docker image pushed to a container registry (e.g., Google Container Registry)

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1. Create a New Git Branch

Open your terminal, ensure you’re on main, then create a feature branch: 
$ git branch
* main
$ git checkout -b minor/deployment-file
Switched to a new branch 'minor/deployment-file'
$ git branch
  main
* minor/deployment-file
Make sure you have committed or stashed any local changes before switching branches.
You can confirm the active branch in your IDE’s integrated terminal.

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2. Define the Deployment Manifest

In the root of your project, create a file named GKE.yaml. This manifest tells Kubernetes how many replicas to run, which Docker image to use, and which port to expose. 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gcp-devops-gke
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gcp
  template:
    metadata:
      labels:
        app: gcp
    spec:
      containers:
        - name: gcp-devops-gke
          image: gcr.io/kodekloud-gcp-training/test-gcpdevops:latest
          ports:
            - containerPort: 5000
          env:
            - name: PORT
              value: "5000"

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3. Manifest Field Reference

Below is a quick reference for the key fields in GKE.yaml:
FieldDescriptionExample
apiVersionKubernetes API version for the Deployment resourceapps/v1
kindResource typeDeployment
metadata.nameUnique name for your Deploymentgcp-devops-gke
spec.replicasNumber of pod replicas to maintain1
spec.selector.matchLabelsLabel selector matching pods managed by this Deploymentapp: gcp
spec.template.metadata.labelsLabels applied to each podapp: gcp
spec.template.spec.containersContainer definitions including image, ports, and env variablesname, image URL, containerPort: 5000, env PORT=5000

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4. Verify and Apply the Manifest

Once GKE.yaml is saved, apply it to your GKE cluster: 
$ kubectl apply -f GKE.yaml
deployment.apps/gcp-devops-gke created
Check the rollout status: 
$ kubectl rollout status deployment/gcp-devops-gke
Always review your manifest for correct image tags and port configurations before applying to production clusters.

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5. Next Steps

Now that your Deployment manifest is live, update your CI/CD pipeline to automate this step. For example, extend your cloudbuild.yaml to:
  1. Build and push the Docker image
  2. Run kubectl apply -f GKE.yaml against your GKE cluster
This ensures every merge to main automatically deploys the latest version.

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