🚀 Task #4 — GitHub Actions with CI + Docker + GitOps ArgoCD + GKE Cluster (CICD)

#argocd #kubernetes #cicd #devops

📌 How CI/CD Works

Step-by-Step Flow

1️⃣ Developer pushes code to GitHub

Push changes inside app/main.go
Push new Dockerfile changes
Push manifest updates

2️⃣ GitHub Actions Runs

Builds Docker image
Pushes new image to GHCR
Updates deployment YAML
Commits YAML back to the repo

3️⃣ ArgoCD Observes Git State

ArgoCD continuously watches repo
Repo changed ➝ ArgoCD detects new commit

4️⃣ ArgoCD Performs Deployment

Applies updated YAML to Kubernetes
Deploys the new version
Ensures cluster matches Git (self-heal)

5️⃣ Result

✅ Fully automated CI/CD
🔥 No kubectl required
⚡ Zero manual deployments
🎯 Pull-based GitOps workflow (secure + stable)

📁 Project Structure

argocd-demo-app/
  ├── app/
  │    └── main.go
  ├── k8s/
  │    └── deployment.yaml
  ├── .github/
  │    └── workflows/
  │         └── ci-cd.yaml
  ├── Dockerfile
  ├── README.md

📌 Part 1 — Application Code

app/main.go

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintln(w, "This is Latchu! Hello from ArgoCD + GitHub Actions + GitOps!")
    })

    fmt.Println("Server running on port 80")
    http.ListenAndServe(":80", nil)
}

📌 Part 2 — Dockerfile

FROM golang:1.22 AS builder
WORKDIR /app
COPY app/ .
RUN go build -o server main.go

FROM debian:stable-slim
COPY --from=builder /app/server /usr/local/bin/server
CMD ["server"]
EXPOSE 80

📌 Part 3 — Kubernetes Deployment

k8s/deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo-app
  labels:
    app: demo-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: demo-app
  template:
    metadata:
      labels:
        app: demo-app
    spec:
      containers:
      - name: demo-app
        image: latchudevops/argocd-demo-app:780e0f9bf323810e2acbbb60b8414b5e34b16af6
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: demo-app
spec:
  type: LoadBalancer
  selector:
    app: demo-app
  ports:
    - port: 80
      targetPort: 80

📌 Part 4 — GitHub Actions CI/CD Pipeline

.github/workflows/ci-cd.yaml

name: CI-CD Pipeline

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: write

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Login to DockerHub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Build & Push Docker Image
        run: |
          IMAGE=latchudevops/argocd-demo-app:${{ github.sha }}
          docker build -t $IMAGE .
          docker push $IMAGE
          echo "IMAGE_NAME=$IMAGE" >> $GITHUB_ENV

      - name: Update Kubernetes Manifest
        run: |
          sed -i "s|image: .*|image: $IMAGE_NAME|g" k8s/deployment.yaml

      - name: Commit Updated Manifest
        run: |
          git config --global user.email "actions@github.com"
          git config --global user.name "GitHub Actions"
          git add k8s/deployment.yaml
          git commit -m "Update image to $IMAGE_NAME" || echo "No changes to commit"
          git push

📌 Part 5 — GitHub Secrets

GitHub repo -> Settings -> Secrets and Variables -> Actions -> Add new repository secret

📌 Part 6 — ArgoCD Setup (GKE)

To install and configure ArgoCD on Google Kubernetes Engine Cluster using below this link

ArgoCD Setup

📌 Part 7 — To start CICD

Push any changes inside app/main.go
GitHub Action Workflow CICD pipeline start the build docker image, push the docker image to the docker hub and update the deployment yaml file inside k8s
ArgoCD continuously watches the k8s mainfest yaml
Manifests changed -> ArgoCD detects new commit
Applies updated YAML to Kubernetes
Deploys the new version into GKE cluster

If you check with GitHub Actions workflow,