Add Docker

Steps

1. Detect the runtime — inspect

   package.json

   ,

   requirements.txt

   ,

   go.mod

   ,

   Cargo.toml

   , etc. to determine the language and runtime.
2. Create a multi-stage

   Dockerfile

   For Node.js (example):
   dockerfile

   FROM node:20-alpine AS base
   
   FROM base AS deps
   WORKDIR /app
   COPY package.json package-lock.json ./
   RUN npm ci --omit=dev
   
   FROM base AS build
   WORKDIR /app
   COPY package.json package-lock.json ./
   RUN npm ci
   COPY . .
   RUN npm run build
   
   FROM base AS runner
   WORKDIR /app
   ENV NODE_ENV=production
   COPY --from=deps /app/node_modules ./node_modules
   COPY --from=build /app/.next ./.next
   COPY --from=build /app/public ./public
   COPY --from=build /app/package.json ./
   EXPOSE 3000
   CMD ["npm", "start"]

   Adapt for the detected framework — adjust the build output directory, entry command, and base image.
3. Create

   .dockerignore

   node_modules
   .next
   .git
   .env*
   *.md

4. Create

   docker-compose.yml

   (if the app has dependencies like a database or Redis):
   yaml

   services:
     app:
       build: .
       ports:
         - "3000:3000"
       env_file: .env
       depends_on:
         - db
     db:
       image: postgres:16-alpine
       environment:
         POSTGRES_DB: app
         POSTGRES_USER: postgres
         POSTGRES_PASSWORD: postgres
       volumes:
         - pgdata:/var/lib/postgresql/data
   volumes:
     pgdata:

5. Add npm scripts (optional)
   json

   {
     "docker:build": "docker build -t myapp .",
     "docker:run": "docker compose up"
   }

Notes

• Use Alpine-based images to minimize image size.
• Never copy

  .env

  files into the image — use

  env_file

  or runtime injection.
• For monorepos, use a

  .dockerignore

  that excludes sibling packages not needed by the target app.
• Add a

  HEALTHCHECK

  instruction for production deployments.