BuildKit: The Next-Generation Build Engine
BuildKit is Docker's new build engine. Faster. Smarter. Better. That's BuildKit.
🎯 The Big Picture​
Think of BuildKit like a modern factory. Old factory (legacy builder) is slow. New factory (BuildKit) is fast. Parallel processing. Smart caching. That's BuildKit.
BuildKit builds Docker images faster. Smarter caching. Parallel builds. It's the future of Docker builds.
What is BuildKit?​
BuildKit is Docker's next-generation build engine:
What it does:
- Faster builds
- Smarter caching
- Parallel execution
- Better security
- Advanced features
Think of it as: Modern factory. Fast. Efficient. Smart.
Why BuildKit?​
The problem with legacy builder:
- Slow builds
- Sequential execution
- Limited caching
- Security issues
- Old architecture
The solution with BuildKit:
- Fast builds
- Parallel execution
- Advanced caching
- Better security
- Modern architecture
Real example: I once had builds taking 10 minutes. With BuildKit, 2 minutes. Same Dockerfile. Never going back.
BuildKit isn't optional. It's essential.
Enabling BuildKit​
Enable BuildKit:
Option 1: Environment variable
export DOCKER_BUILDKIT=1
docker build -t my-app:1.0 .
Option 2: Dockerfile syntax
# syntax=docker/dockerfile:1
FROM node:18-alpine
Option 3: docker buildx
docker buildx build -t my-app:1.0 .
Why: BuildKit enabled. Faster builds.
The Modern Factory Analogy​
Think of BuildKit like a modern factory:
Legacy builder: Old factory
- Sequential production
- Slow
- Limited automation
BuildKit: Modern factory
- Parallel production
- Fast
- Advanced automation
- Smart caching
Once you see it this way, BuildKit makes perfect sense.
BuildKit Features​
1. Parallel Builds​
Build stages in parallel:
# syntax=docker/dockerfile:1
FROM node:18 AS deps
COPY package*.json ./
RUN npm ci
FROM node:18 AS build
COPY . .
RUN npm run build
FROM node:18-alpine AS runtime
COPY --from=deps /app/node_modules ./node_modules
COPY --from=build /app/dist ./dist
Why: Faster. Parallel execution.
2. Advanced Caching​
Better caching:
# syntax=docker/dockerfile:1
FROM node:18-alpine
RUN --mount=type=cache,target=/root/.npm \
npm ci
Why: Faster builds. Reuse cache.
3. Secret Mounts​
Build-time secrets:
# syntax=docker/dockerfile:1
RUN --mount=type=secret,id=api_key \
echo $API_KEY > /app/.env
Build:
docker buildx build --secret id=api_key,src=./api_key.txt -t my-app .
Why: Secure. Not in layers.
4. SSH Mounts​
SSH agent forwarding:
# syntax=docker/dockerfile:1
RUN --mount=type=ssh \
git clone git@github.com:user/repo.git
Build:
docker buildx build --ssh default=$SSH_AUTH_SOCK -t my-app .
Why: Access private repos. Secure.
5. Build Arguments​
Advanced build args:
# syntax=docker/dockerfile:1
ARG BUILDKIT_INLINE_CACHE=1
FROM node:18-alpine
Why: Inline cache. Faster builds.
Real-World Example: BuildKit Optimization​
Before (legacy builder):
FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build
CMD ["node", "server.js"]
Build time: 5 minutes
After (BuildKit):
# syntax=docker/dockerfile:1
FROM node:18 AS deps
WORKDIR /app
COPY package*.json ./
RUN --mount=type=cache,target=/root/.npm \
npm ci --only=production
FROM node:18-alpine AS build
WORKDIR /app
COPY . .
RUN npm run build
FROM node:18-alpine AS runtime
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY --from=build /app/dist ./dist
USER nodejs
CMD ["node", "server.js"]
Build time: 1.5 minutes
That's BuildKit. Faster. Better.
BuildKit Best Practices​
1. Use Buildx​
Use buildx:
docker buildx build -t my-app:1.0 .
Why: BuildKit enabled. Better features.
2. Use Cache Mounts​
Cache dependencies:
RUN --mount=type=cache,target=/root/.npm \
npm ci
Why: Faster builds. Reuse cache.
3. Use Secret Mounts​
Secure secrets:
RUN --mount=type=secret,id=api_key \
echo $API_KEY > .env
Why: Secure. Not in layers.
4. Use Multi-Stage Builds​
Optimize images:
FROM node:18 AS builder
# ... build
FROM node:18-alpine
COPY --from=builder /app/dist ./dist
Why: Smaller images. Faster builds.
5. Use Parallel Stages​
Build in parallel:
FROM node:18 AS deps
# ... dependencies
FROM node:18 AS build
# ... build
Why: Faster. Parallel execution.
My Take: BuildKit Strategy​
Here's what I do:
All builds:
- Enable BuildKit
- Use buildx
- Cache mounts
- Multi-stage builds
Production:
- Secret mounts
- SSH mounts
- Advanced caching
- Optimized Dockerfiles
The key: Always use BuildKit. Faster. Better. Future-proof.
Memory Tip: The Modern Factory Analogy​
BuildKit = Modern factory
Legacy: Old factory (slow) BuildKit: Modern factory (fast) Parallel: Multiple lines Caching: Smart inventory
Once you see it this way, BuildKit makes perfect sense.
Common Mistakes​
- Not enabling BuildKit: Missing speed improvements
- Not using cache mounts: Slower builds
- Secrets in layers: Security risk
- Sequential builds: Missing parallelism
- Not using buildx: Missing features
Hands-On Exercise: Use BuildKit​
1. Enable BuildKit:
export DOCKER_BUILDKIT=1
2. Create optimized Dockerfile:
# syntax=docker/dockerfile:1
FROM node:18-alpine AS deps
WORKDIR /app
COPY package*.json ./
RUN --mount=type=cache,target=/root/.npm \
npm ci
FROM node:18-alpine
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
CMD ["node", "server.js"]
3. Build with buildx:
docker buildx build -t my-app:1.0 .
4. Compare times:
# Legacy builder
DOCKER_BUILDKIT=0 time docker build -t my-app:1.0 .
# BuildKit
DOCKER_BUILDKIT=1 time docker build -t my-app:1.0 .
See the difference. BuildKit is faster.
Key Takeaways​
- BuildKit is faster - Parallel execution, smart caching
- Enable BuildKit - Environment variable or buildx
- Use cache mounts - Faster dependency installation
- Use secret mounts - Secure build-time secrets
- Use multi-stage builds - Smaller, faster builds
- Always use buildx - Best BuildKit experience
What's Next?​
Now that you understand BuildKit, let's learn about Docker Desktop. Next: Docker Desktop.
Remember: BuildKit is like a modern factory. Fast. Efficient. Smart. Always use it. Faster builds. Better experience.