Merge pull request #7 from elizabeth-ikechukwu/feat/week2-dockerize-backend

dockerize backend -  week-2 docs

.gitignore

@@ -137,3 +137,5 @@ dist
 # Vite logs files
 vite.config.js.timestamp-*
 vite.config.ts.timestamp-*
+postman/
+.postman

app/backend/.dockerignore

@@ -0,0 +1,5 @@
+node_modules
+.env
+.git
+.gitignore
+*.log

app/backend/Dockerfile

@@ -0,0 +1,13 @@
+FROM node:24-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+
+RUN npm ci --only=production
+
+COPY . .
+
+EXPOSE 3000
+
+CMD ["node", "server.js"]

docs/week-2-update.md

@@ -0,0 +1,53 @@
+# Week 2: Dockerizing the Backend
+
+## What I Did
+Containerized the Node.js backend using Docker. Wrote a Dockerfile 
+from scratch, built the image locally, ran the container, and verified 
+all API endpoints.
+
+## Dockerfile
+- Base image: node:24-alpine
+- Working directory: /app
+- Dependencies installed with npm ci --only=production
+- App starts via docker-entrypoint.sh
+- Image size: 237MB across 15 layers
+
+## Steps Taken
+1. Wrote the Dockerfile in app/backend
+2. Built the image: docker build -t task-backend:v1 .
+3. Ran the container: docker run -d -p 3000:3000 --name task-backend task-backend:v1
+4. Tested all 6 endpoints via Postman
+
+## Endpoints Verified
+| Method | Route | Status |
+|--------|-------|--------|
+| GET | / | 200 OK |
+| GET | /health | 200 OK |
+| GET | /tasks | 200 OK |
+| POST | /tasks | 200 OK |
+| PATCH | /tasks/:id | 200 OK |
+| DELETE | /tasks/:id | 200 OK |
+
+## Problems and Fixes
+**Problem:** Docker build failed with exit code 1 on npm ci  
+**Root cause:** DNS failure — Docker could not resolve auth.docker.io  
+**Fix:** Added Google DNS (8.8.8.8, 8.8.4.4) to Docker Engine settings
+
+## Key Concepts Learned
+- Dockerfile instructions become image layers — each RUN, COPY, ENV is a layer
+- Docker caches layers — unchanged layers are reused on rebuild
+- Port mapping (-p host:container) exposes the container to localhost
+- Docker Desktop is a GUI over the Docker CLI — same underlying engine
+
+## Commands Reference
+```bash
+docker build -t task-backend:v1 .
+docker run -d -p 3000:3000 --name task-backend task-backend:v1
+docker ps
+docker start task-backend
+docker images
+```
+
+## Week 3 Preview
+Week 3 will cover adding a frontend service and connecting both 
+services using Docker Compose.