Add Docker containerization with GitHub Actions CI/CD pipeline

[Copilot]

Implements automated Docker image builds and deployment to GitHub Container Registry (GHCR) with CI/CD pipeline.

Docker Images

Backend (backend/Dockerfile)

• Multi-stage build: Node 20 build → slim production image
• Auto-removes circular "backend": "file:" dependency during build
• Non-root user, health check, ~200MB final size

Frontend (frontend/Dockerfile)

• Multi-stage build: Node 20 build → nginx:alpine serve
• SPA routing configured, health check, ~50MB final size

Both exclude package-lock.json via .dockerignore to avoid circular dependency errors.

GitHub Actions Workflow

.github/workflows/docker-build-push.yml triggers on:

• Push to main/develop → build amd64, push to GHCR
• Version tags (v*.*.*) → build amd64+arm64, push to GHCR
• Pull requests → build only, no push
• Manual dispatch

Tagging strategy: latest, {branch}, {sha}, v{major}.{minor}.{patch}

Uses GitHub Actions cache for ~10x faster rebuilds.

Local Development

docker-compose.yml provides complete stack:

services:
  mongo:     # MongoDB with persistent volume
  backend:   # Connects to mongo, requires JWT_SECRET in .env
  frontend:  # nginx serving React app

Quick start:

cp .env.example .env    # Set JWT_SECRET (required)
docker-compose up -d

Container Registry

Images available at:

• ghcr.io/codingf0x/chat-app/backend:latest
• ghcr.io/codingf0x/chat-app/frontend:latest

Documentation

• QUICKSTART.md - 5-minute setup guide
• DOCKER.md - Complete deployment reference
• README.md - Updated with Docker section

Original prompt

How to setup container registry which create an image off docker file from my file and push it to the container registry?

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.