Docker Basics

mkdir node-api && cd node-api
npm init -y
npm pkg set type=module
npm install express@5
npm install -D typescript@5.6 tsx @types/express @types/node

FROM node:24-bookworm-slim
 
WORKDIR /app
COPY package*.json ./
RUN npm ci --omit=dev
COPY dist ./dist
 
ENV NODE_ENV=production
USER node
EXPOSE 3000
CMD ["node", "dist/main.js"]

FROM node:24-bookworm-slim AS build
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY tsconfig.json ./
COPY src ./src
RUN npm run build
 
FROM node:24-bookworm-slim
WORKDIR /app
COPY package*.json ./
RUN npm ci --omit=dev
COPY --from=build /app/dist ./dist
USER node
CMD ["node", "dist/main.js"]

import express from "express";
 
const app = express();
const port = Number(process.env.PORT ?? 3000);
 
app.get("/health", (_req, res) => {
  res.json({ status: "ok" });
});
 
app.listen(port, "0.0.0.0", () => {
  console.log(`listening on ${port}`);
});

docker build -t my-api:local .
docker run --rm -p 3000:3000 -e PORT=3000 my-api:local
curl http://localhost:3000/health

{
  "scripts": {
    "build": "tsc",
    "start": "node dist/main.js",
    "docker:build": "docker build -t my-api:local .",
    "docker:run": "docker run --rm -p 3000:3000 -e PORT=3000 my-api:local"
  }
}

HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
  CMD node -e "fetch('http://127.0.0.1:' + (process.env.PORT||3000) + '/health').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"

FROM node:24-bookworm-slim AS base
WORKDIR /app
COPY package*.json ./
 
FROM base AS dev
RUN npm ci
COPY . .
CMD ["npx", "tsx", "watch", "src/main.ts"]
 
FROM base AS prod
RUN npm ci --omit=dev
COPY dist ./dist
USER node
CMD ["node", "dist/main.js"]

docker build --target dev -t my-api:dev .
docker build --target prod -t my-api:prod .

# compose.yml
services:
  api:
    build: .
    ports:
      - "3000:3000"
    environment:
      NODE_ENV: development
      PORT: 3000
      DATABASE_URL: postgres://postgres:postgres@db:5432/app
    depends_on:
      db:
        condition: service_healthy
  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_PASSWORD: postgres
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 5s
      timeout: 3s
      retries: 5

FROM node:24-bookworm-slim@sha256:abc123def456...