Docker for Node.js：誰も教えてくれない本番対応セットアップ | Akousa

2025年11月10日24分で読めます

Docker for Node.js：誰も教えてくれない本番対応セットアップ

マルチステージビルド、非rootユーザー、ヘルスチェック、シークレット管理、イメージサイズ最適化。すべてのNode.jsプロダクションデプロイで使っているDockerパターン。

Most Node.js Dockerfiles in production are bad. Not "slightly suboptimal" bad. I mean running as root, shipping 600MB images with devDependencies baked in, no health checks, and secrets hardcoded in environment variables that anyone with docker inspect can read.

I know because I wrote those Dockerfiles. For years. They worked, so I never questioned them. Then one day a security audit flagged our container running as PID 1 root with write access to the entire filesystem, and I realized that "works" and "production-ready" are very different bars.

This setup is a production-tested baseline for Node.js services. Every pattern here exists because the weaker alternative tends to fail under real traffic.

Why Your Current Dockerfile is Probably Wrong

Let me guess what your Dockerfile looks like:

dockerfile

FROM

dockerfile

# Single stage: ~600MB
FROM node:20
WORKDIR /app
COPY . .
RUN npm install
CMD ["node", "server.js"]
 
# Multi-stage: ~150MB
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build
 
FROM node:20-alpine AS runner
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./
CMD ["node", "dist/server.js"]

dockerfile

# ============================================
# Stage 1: Install dependencies
# ============================================
FROM node:20-alpine AS deps
 
# Security: create a working directory before anything else
WORKDIR /app
 
# Install dependencies based on lockfile
# Copy ONLY package files first — this is critical for layer caching
COPY package.json package-lock.json ./
 
# ci is better than install: it's faster, stricter, and reproducible
# --omit=dev excludes devDependencies from this stage
RUN npm ci --omit=dev
 
# ============================================
# Stage 2: Build the application
# ============================================
FROM node:20-alpine AS builder
 
WORKDIR /app
 
# Copy package files and install ALL dependencies (including dev)
COPY package.json package-lock.json ./
RUN npm ci
 
# NOW copy source code — changes here don't invalidate the npm ci cache
COPY . .
 
# Build the application (TypeScript compile, Next.js build, etc.)
RUN npm run build
 
# ============================================
# Stage 3: Production runner
# ============================================
FROM node:20-alpine AS runner
 
# Add labels for image metadata
LABEL maintainer="your-email@example.com"
LABEL org.opencontainers.image.source="https://github.com/yourorg/yourrepo"
 
# Security: install dumb-init for proper PID 1 signal handling
RUN apk add --no-cache dumb-init
 
# Security: set NODE_ENV before anything else
ENV NODE_ENV=production
 
# Security: use non-root user
# The node image already includes a 'node' user (uid 1000)
USER node
 
# Create app directory owned by node user
WORKDIR /app
 
# Copy production dependencies from deps stage
COPY --from=deps --chown=node:node /app/node_modules ./node_modules
 
# Copy built application from builder stage
COPY --from=deps --chown=node:node /app/package.json ./
COPY --from=builder --chown=node:node /app/dist ./dist
 
# Expose the port (documentation only — doesn't publish it)
EXPOSE 3000
 
# Health check: curl isn't available in alpine, use node
HEALTHCHECK --interval=30s --timeout=10s --start-period=40s --retries=3 \
  CMD node -e "require('http').get('http://localhost:3000/health', (r) => { process.exit(r.statusCode === 200 ? 0 : 1) })"
 
# Use dumb-init as PID 1 to handle signals properly
ENTRYPOINT ["dumb-init", "--"]
 
# Start the application
CMD ["node", "dist/server.js"]

javascript

// server.js
const server = app.listen(3000);
 
process.on("SIGTERM", () => {
  console.log("SIGTERM received, shutting down gracefully");
  server.close(() => {
    console.log("HTTP server closed");
    // Close database connections, flush logs, etc.
    process.exit(0);
  });
});

# .dockerignore
node_modules
npm-debug.log*
.git
.gitignore
.env
.env.*
!.env.example
Dockerfile
docker-compose*.yml
.dockerignore
README.md
LICENSE
.github
.vscode
.idea
coverage
.nyc_output
*.test.ts
*.test.js
*.spec.ts
*.spec.js
__tests__
test
tests
docs
.husky
.eslintrc*
.prettierrc*
tsconfig.json
jest.config.*
vitest.config.*

dockerfile

# syntax=docker/dockerfile:1
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
 
# Mount the secret at build time — it's never stored in the image
RUN --mount=type=secret,id=npmrc,target=/app/.npmrc \
    npm ci
 
COPY . .
RUN npm run build

yaml

# docker-compose.yml (Swarm mode)
version: "3.8"
services:
  api:
    image: myapp:latest
    secrets:
      - db_password
      - api_key
 
secrets:
  db_password:
    external: true
  api_key:
    external: true

javascript

import { readFileSync } from "fs";
 
function getSecret(name) {
  try {
    return readFileSync(`/run/secrets/${name}`, "utf8").trim();
  } catch {
    // Fall back to environment variable for local development
    return process.env[name.toUpperCase()];
  }
}
 
const dbPassword = getSecret("db_password");

dockerfile

HEALTHCHECK --interval=30s --timeout=10s --start-period=40s --retries=3 \
  CMD node -e "require('http').get('http://localhost:3000/health', (r) => { process.exit(r.statusCode === 200 ? 0 : 1) })"

javascript

// healthcheck.js
const http = require("http");
 
const options = {
  hostname: "localhost",
  port: 3000,
  path: "/health",
  timeout: 5000,
};
 
const req = http.request(options, (res) => {
  process.exit(res.statusCode === 200 ? 0 : 1);
});
 
req.on("error", () => process.exit(1));
req.on("timeout", () => {
  req.destroy();
  process.exit(1);
});
 
req.end();

javascript

app.get("/health", async (req, res) => {
  const checks = {
    uptime: process.uptime(),
    timestamp: Date.now(),
    status: "ok",
  };
 
  try {
    // Check database connection
    await db.query("SELECT 1");
    checks.database = "connected";
  } catch (err) {
    checks.database = "disconnected";
    checks.status = "degraded";
  }
 
  try {
    // Check Redis connection
    await redis.ping();
    checks.redis = "connected";
  } catch (err) {
    checks.redis = "disconnected";
    checks.status = "degraded";
  }
 
  const statusCode = checks.status === "ok" ? 200 : 503;
  res.status(statusCode).json(checks);
});

yaml

# docker-compose.dev.yml
services:
  app:
    build:
      context: .
      dockerfile: Dockerfile.dev
      args:
        NODE_VERSION: "20"
    ports:
      - "3000:3000"
      - "9229:9229" # Node.js debugger
    volumes:
      # Mount source code for hot reload
      - .:/app
      # Anonymous volume to preserve node_modules from the image
      # This prevents the host's node_modules from overriding the container's
      - /app/node_modules
    environment:
      - NODE_ENV=development
      - DATABASE_URL=postgres://postgres:devpassword@db:5432/myapp_dev
      - REDIS_URL=redis://redis:6379
    env_file:
      - .env.local
    depends_on:
      db:
        condition: service_healthy
      redis:
        condition: service_started
    command: npm run dev
 
  db:
    image: postgres:16-alpine
    ports:
      - "5432:5432"
    environment:
      POSTGRES_DB: myapp_dev
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: devpassword
    volumes:
      # Named volume for persistent data across container restarts
      - pgdata:/var/lib/postgresql/data
      # Initialization scripts
      - ./scripts/init-db.sql:/docker-entrypoint-initdb.d/init.sql
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 10s
      timeout: 5s
      retries: 5
 
  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"
    volumes:
      - redisdata:/data
    command: redis-server --appendonly yes
 
  # Optional: database admin UI
  adminer:
    image: adminer:latest
    ports:
      - "8080:8080"
    depends_on:
      - db
 
volumes:
  pgdata:
  redisdata:

dockerfile

# Dockerfile.dev
ARG NODE_VERSION=20
FROM node:${NODE_VERSION}-alpine
 
WORKDIR /app
 
# Install all dependencies (including devDependencies)
COPY package*.json ./
RUN npm ci
 
# Source code is mounted via volume, not copied
# But we still need it for the initial build
COPY . .
 
EXPOSE 3000 9229
 
CMD ["npm", "run", "dev"]

yaml

# docker-compose.prod.yml
services:
  app:
    image: ghcr.io/yourorg/myapp:${TAG:-latest}
    restart: unless-stopped
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production
    env_file:
      - .env.production
    deploy:
      resources:
        limits:
          cpus: "1.0"
          memory: 512M
        reservations:
          cpus: "0.25"
          memory: 128M
      replicas: 2
    healthcheck:
      test:
        [
          "CMD",
          "node",
          "-e",
          "require('http').get('http://localhost:3000/health', r => process.exit(r.statusCode === 200 ? 0 : 1))",
        ]
      interval: 30s
      timeout: 10s
      start_period: 40s
      retries: 3
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "3"
    networks:
      - internal
      - web
    depends_on:
      db:
        condition: service_healthy
      redis:
        condition: service_started
 
  db:
    image: postgres:16-alpine
    restart: unless-stopped
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      POSTGRES_DB: myapp
      POSTGRES_USER: ${DB_USER}
      POSTGRES_PASSWORD: ${DB_PASSWORD}
    deploy:
      resources:
        limits:
          cpus: "1.0"
          memory: 1G
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${DB_USER}"]
      interval: 10s
      timeout: 5s
      retries: 5
    networks:
      - internal
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "3"
 
  redis:
    image: redis:7-alpine
    restart: unless-stopped
    command: >
      redis-server
      --appendonly yes
      --maxmemory 256mb
      --maxmemory-policy allkeys-lru
    volumes:
      - redisdata:/data
    deploy:
      resources:
        limits:
          cpus: "0.5"
          memory: 512M
    networks:
      - internal
    logging:
      driver: "json-file"
      options:
        max-size: "5m"
        max-file: "3"
 
volumes:
  pgdata:
    driver: local
  redisdata:
    driver: local
 
networks:
  internal:
    driver: bridge
  web:
    external: true

dockerfile

# ============================================
# Stage 1: Install dependencies
# ============================================
FROM node:20-alpine AS deps
RUN apk add --no-cache libc6-compat
WORKDIR /app
 
COPY package.json package-lock.json ./
RUN npm ci
 
# ============================================
# Stage 2: Build the application
# ============================================
FROM node:20-alpine AS builder
WORKDIR /app
 
COPY --from=deps /app/node_modules ./node_modules
COPY . .
 
# Disable Next.js telemetry during build
ENV NEXT_TELEMETRY_DISABLED=1
 
RUN npm run build
 
# ============================================
# Stage 3: Production runner
# ============================================
FROM node:20-alpine AS runner
WORKDIR /app
 
RUN apk add --no-cache dumb-init
 
ENV NODE_ENV=production
ENV NEXT_TELEMETRY_DISABLED=1
 
# Non-root user
RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs
 
# Copy public assets
COPY --from=builder /app/public ./public
 
# Set up the standalone output directory
# Automatically leverages output traces to reduce image size
# https://nextjs.org/docs/advanced-features/output-file-tracing
RUN mkdir .next
RUN chown nextjs:nodejs .next
 
# Copy the standalone server and static files
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
 
USER nextjs
 
EXPOSE 3000
 
ENV PORT=3000
ENV HOSTNAME="0.0.0.0"
 
HEALTHCHECK --interval=30s --timeout=10s --start-period=40s --retries=3 \
  CMD node -e "require('http').get('http://localhost:3000/api/health', (r) => { process.exit(r.statusCode === 200 ? 0 : 1) })"
 
ENTRYPOINT ["dumb-init", "--"]
CMD ["node", "server.js"]

myapp:latest (alpine 3.19.1)
=============================
Total: 0 (UNKNOWN: 0, LOW: 0, MEDIUM: 0, HIGH: 0, CRITICAL: 0)

Node.js (node_modules/package-lock.json)
=========================================
Total: 2 (UNKNOWN: 0, LOW: 0, MEDIUM: 1, HIGH: 1, CRITICAL: 0)

┌──────────────┬────────────────┬──────────┬────────┬───────────────┐
│   Library    │ Vulnerability  │ Severity │ Status │ Fixed Version │
├──────────────┼────────────────┼──────────┼────────┼───────────────┤
│ semver       │ CVE-2022-25883 │ HIGH     │ fixed  │ 7.5.4         │
│ word-wrap    │ CVE-2023-26115 │ MEDIUM   │ fixed  │ 1.2.4         │
└──────────────┴────────────────┴──────────┴────────┴───────────────┘

yaml

# .github/workflows/docker.yml
- name: Build image
  run: docker build -t myapp:${{ github.sha }} .
 
- name: Scan image
  uses: aquasecurity/trivy-action@master
  with:
    image-ref: myapp:${{ github.sha }}
    exit-code: 1
    severity: CRITICAL,HIGH
    ignore-unfixed: true

yaml

# .github/workflows/docker.yml
name: Build and Push Docker Image
 
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
 
env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}
 
jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      security-events: write
 
    steps:
      - name: Checkout
        uses: actions/checkout@v4
 
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
 
      - name: Log in to Container Registry
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
 
      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=sha
            type=ref,event=branch
            type=semver,pattern={{version}}
 
      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max
 
      - name: Scan image with Trivy
        uses: aquasecurity/trivy-action@master
        with:
          image-ref: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:sha-${{ github.sha }}
          exit-code: 1
          severity: CRITICAL,HIGH
          ignore-unfixed: true
 
      - name: Upload Trivy results
        if: always()
        uses: github/codeql-action/upload-sarif@v3
        with:
          sarif_file: trivy-results.sarif

dockerfile

# Build-time configuration
ARG NODE_VERSION=20
FROM node:${NODE_VERSION}-alpine
 
# Runtime configuration
ENV PORT=3000
 
# WRONG: This makes the secret visible in the image
ARG API_KEY
ENV API_KEY=${API_KEY}
 
# RIGHT: Pass secrets at runtime
# docker run -e API_KEY=secret myapp

yaml

# docker-compose.monitoring.yml
services:
  prometheus:
    image: prom/prometheus:latest
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
      - prometheus_data:/prometheus
    ports:
      - "9090:9090"
    networks:
      - internal
 
  grafana:
    image: grafana/grafana:latest
    volumes:
      - grafana_data:/var/lib/grafana
    ports:
      - "3001:3000"
    environment:
      - GF_SECURITY_ADMIN_PASSWORD=${GRAFANA_PASSWORD}
    networks:
      - internal
 
volumes:
  prometheus_data:
  grafana_data:

javascript

import { collectDefaultMetrics, Registry, Histogram } from "prom-client";
 
const register = new Registry();
collectDefaultMetrics({ register });
 
const httpRequestDuration = new Histogram({
  name: "http_request_duration_seconds",
  help: "Duration of HTTP requests in seconds",
  labelNames: ["method", "route", "status_code"],
  buckets: [0.01, 0.05, 0.1, 0.5, 1, 5],
  registers: [register],
});
 
// Middleware
app.use((req, res, next) => {
  const end = httpRequestDuration.startTimer();
  res.on("finish", () => {
    end({ method: req.method, route: req.route?.path || req.path, status_code: res.statusCode });
  });
  next();
});
 
// Metrics endpoint
app.get("/metrics", async (req, res) => {
  res.set("Content-Type", register.contentType);
  res.end(await register.metrics());
});

Approach	Image Size
`node:20` + `npm install`	1.1 GB
`node:20-slim` + `npm install`	420 MB
`node:20-alpine` + `npm ci`	280 MB
Multi-stage + alpine + production deps only	150 MB
Multi-stage + alpine + pruned deps	95 MB

Approach	Image Size
`node:20` + full `node_modules` + `.next`	1.4 GB
`node:20-alpine` + full `node_modules` + `.next`	600 MB
`node:20-alpine` + standalone output	120 MB

Why Your Current Dockerfile is Probably Wrong

Running as Root

Installing devDependencies in Production

COPY Everything

No Health Checks

No Layer Caching Strategy

Multi-Stage Builds: The Single Biggest Win

Real Size Comparisons

Why Alpine?

The Complete Production Dockerfile

Why Three Stages Instead of Two?

Why dumb-init?

The .dockerignore File

Layer Caching: Stop Waiting 3 Minutes Per Build

The Wrong Order

The Right Order

Cache Mount for npm

Using ARG for Cache Busting

Secrets Management: Stop Putting Secrets in Your Dockerfile

The Three Levels of Secrets

.env Files and Docker

Health Checks: Let Docker Know Your App is Actually Working

The HEALTHCHECK Instruction

Why Not Use curl?

The Health Endpoint

Why Health Checks Matter for Orchestrators

docker-compose for Development

Key Development Patterns

The Development Dockerfile

Production Docker Compose

What's Different From Development

Next.js Specific: The Standalone Output

The Next.js Production Dockerfile

Size Comparison for Next.js

Static File Handling

Sharp for Image Optimization

Image Scanning and Security

Trivy: Scan Your Images

Read-Only Filesystem

Drop All Capabilities

Pin Your Base Image Digest

CI/CD Integration: Putting It All Together

BuildKit Cache in CI

Common Pitfalls and How to Avoid Them

The node_modules Inside the Image vs Host Conflict

SIGTERM Handling in TypeScript Projects

Memory Limits and Node.js

Timezone Issues

Build Arguments vs Environment Variables

Monitoring in Production

チェックリスト

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