Hello World NodeJS example using Multi-Stage

Dockerfile

# Stage 1: build
FROM node:18-slim AS build

WORKDIR /app

# Copiar dependencias
COPY package*.json ./

RUN npm install

# Copiamos el código (puede ser directamente COPY . .)
COPY app.js ./

# Stage 2: runtime
FROM node:18-slim AS runtime

WORKDIR /app

# Crear usuario/grupo NO ROOT
RUN groupadd --gid 10001 appgroup \
 && useradd --uid 10001 --gid 10001 --create-home --home-dir /home/app appuser

# Copiar código fuente (SOLO lo necesario) desde build
COPY --from=build /app/node_modules ./node_modules
COPY --from=build /app/package*.json ./
COPY --from=build /app/app.js ./

# Permisos y ejecución como usuario NO ROOT
RUN chown -R appuser:appgroup /app
USER appuser

EXPOSE 3000
CMD ["node", "app.js"]