docker-patterns

name	docker-patterns
description	Docker configuration patterns for Next.js applications. This skill should be used when the user asks to "dockerize Next.js", "create a Dockerfile for Next.js", "set up Docker for Next.js", "docker compose for Next.js", "build Next.js with Docker", "deploy Next.js in Docker", "Next.js standalone Docker", or needs to containerize a Next.js application for development or production.

Docker Patterns for Next.js

Patterns for containerizing Next.js applications using the standalone output mode. Covers development, production, and docker-compose configurations.

Prerequisites

• Docker 20+ and Docker Compose v2+
• Next.js 14+ project with App Router
• pnpm (or npm/yarn — adjust commands accordingly)

Step 1: Enable Standalone Output

Set output: 'standalone' in next.config.ts — this creates a self-contained build that includes only the necessary dependencies, reducing the Docker image size significantly.

import type { NextConfig } from 'next'

const nextConfig: NextConfig = {
  output: 'standalone',
}

export default nextConfig

Step 2: Production Dockerfile (Multi-Stage)

Multi-stage build that produces a minimal production image (~150MB vs ~1GB without standalone).

FROM node:22-alpine AS base

RUN corepack enable && corepack prepare pnpm@latest --activate

# --- Dependencies ---
FROM base AS deps
WORKDIR /app
COPY package.json pnpm-lock.yaml ./
RUN pnpm install --frozen-lockfile

# --- Build ---
FROM base AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
RUN pnpm build

# --- Production ---
FROM node:22-alpine AS runner
WORKDIR /app

ENV NODE_ENV=production

RUN addgroup --system --gid 1001 nodejs && \
    adduser --system --uid 1001 nextjs

COPY --from=builder /app/public ./public
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"

CMD ["node", "server.js"]

Key points:

• deps stage caches node_modules — rebuilds only when package.json/pnpm-lock.yaml change
• builder stage compiles the app — standalone output bundles server + minimal deps into .next/standalone
• runner stage copies only standalone + static + public — no node_modules, no source code
• Non-root nextjs user for security

Step 3: Development Dockerfile

Simpler single-stage image for development with hot reload via volume mounts.

FROM node:22-alpine

RUN corepack enable && corepack prepare pnpm@latest --activate

WORKDIR /app

COPY package.json pnpm-lock.yaml ./
RUN pnpm install --frozen-lockfile

COPY . .

EXPOSE 3000

CMD ["pnpm", "dev"]

Step 4: Docker Compose

Define both dev and production services. Use docker compose up dev for development or docker compose up app for production.

services:
  # Development — hot reload via volume mounts
  dev:
    build:
      context: .
      dockerfile: Dockerfile.dev
    ports:
      - "3000:3000"
    volumes:
      - .:/app
      - /app/node_modules
      - /app/.next
    env_file:
      - .env.local
    restart: unless-stopped

  # Production — standalone build
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "3000:3000"
    env_file:
      - .env.local
    restart: unless-stopped

Volume mount notes for dev service:

• .:/app — mounts source code for hot reload
• /app/node_modules — anonymous volume prevents host node_modules from overwriting container's
• /app/.next — anonymous volume prevents build cache conflicts

Step 5: .dockerignore

Exclude files that should not be copied into the Docker build context.

node_modules
.next
.git
.gitignore
.claude
.cursor
.vercel
*.md
deploy.sh
scripts
docs

Keep .env.local out of the image — pass it via env_file in docker-compose or --env-file at runtime. Never bake secrets into the image.

Common Patterns

With External Services (Directus, PostgreSQL, etc.)

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "3000:3000"
    env_file:
      - .env.local
    depends_on:
      directus:
        condition: service_healthy

  directus:
    image: directus/directus:latest
    ports:
      - "8055:8055"
    environment:
      DB_CLIENT: sqlite3
      DB_FILENAME: /directus/database/data.db
      ADMIN_EMAIL: [e-mail]
      ADMIN_PASSWORD: admin
    healthcheck:
      test: ["CMD", "wget", "--spider", "http://localhost:8055/server/health"]
      interval: 10s
      timeout: 5s
      retries: 3

Build Arguments for Environment-Specific Builds

# In Dockerfile builder stage
ARG NEXT_PUBLIC_API_URL
ENV NEXT_PUBLIC_API_URL=$NEXT_PUBLIC_API_URL
RUN pnpm build

# In docker-compose.yml
services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
      args:
        NEXT_PUBLIC_API_URL: https://api.example.com

Use ARG + ENV for NEXT_PUBLIC_* variables — they are inlined at build time, so they must be available during pnpm build.

Health Check

services:
  app:
    # ...
    healthcheck:
      test: ["CMD", "wget", "--spider", "http://localhost:3000/api/health"]
      interval: 30s
      timeout: 5s
      retries: 3
      start_period: 10s

Commands

# Build and start dev
docker compose up dev --build

# Build and start production
docker compose up app --build

# Build production image only
docker compose build app

# Run in background
docker compose up app -d

# View logs
docker compose logs app --tail 50

# Stop all
docker compose down

Troubleshooting

Issue	Cause	Fix
public: not found in COPY	No public/ directory in project	Create public/ with at least one file, or use COPY --from=builder /app/public ./public 2>/dev/null || true
Hot reload not working in dev	Volume mount not matching	Ensure .:/app is set and /app/node_modules is an anonymous volume
NEXT_PUBLIC_* vars empty at runtime	These are inlined at build time	Pass them as ARG in Dockerfile and set during docker compose build
Image too large (>500MB)	Not using standalone output	Set output: 'standalone' in next.config.ts
Permission denied errors	Running as root	Use non-root user with --chown on COPY commands

What This Skill Does NOT Cover

• CI/CD pipeline Docker builds — see deployment guides
• Kubernetes or Docker Swarm orchestration
• Multi-architecture builds (ARM/x86) — use docker buildx
• Docker registry publishing