202 — Advanced Dockerfile Techniques

Master multi-stage builds, build optimization, health checks, and advanced patterns for production-ready Docker images.

Learning Objectives

Create multi-stage builds for smaller images

Implement health checks in images

Use advanced COPY and RUN patterns

Optimize images for production

Handle signals and graceful shutdowns

Step 1

Understanding multi-stage builds

Learn why multi-stage builds are essential for production images.

Commands to Run

mkdir multi-stage-demo && cd multi-stage-demo

cat > app.go << 'EOF'
package main
import "fmt"
func main() {
    fmt.Println("Hello from Go!")
}
EOF

cat > Dockerfile.single << 'EOF'
FROM golang:1.21
WORKDIR /app
COPY app.go .
RUN go build -o myapp app.go
CMD ["./myapp"]
EOF

docker build -f Dockerfile.single -t go-app:single .

docker images go-app:single

What This Does

A single-stage build includes the entire Go toolchain in the final image. This results in a ~800MB image for a simple binary that could be just a few MB.

Expected Outcome

The image builds successfully but is very large (800MB+) because it includes the full Go compiler and build tools.

Pro Tips

1
Single-stage builds are simpler but inefficient for compiled languages
2
The final image includes build tools, source code, and dependencies
3
Larger images mean slower deployments and larger attack surface