multi-stage-dockerfile

Your goal is to help me create efficient multi-stage Dockerfiles that follow best practices, resulting in smaller, more secure container images.

Multi-Stage Structure

Use a builder stage for compilation, dependency installation, and other build-time operations
Use a separate runtime stage that only includes what's needed to run the application
Copy only the necessary artifacts from the builder stage to the runtime stage
Use meaningful stage names with the AS keyword (e.g., FROM node:18 AS builder)
Place stages in logical order: dependencies → build → test → runtime

Start with official, minimal base images when possible
Specify exact version tags to ensure reproducible builds (e.g., python:3.11-slim not just python)
Consider distroless images for runtime stages where appropriate
Use Alpine-based images for smaller footprints when compatible with your application
Ensure the runtime image has the minimal necessary dependencies

Organize commands to maximize layer caching
Place commands that change frequently (like code changes) after commands that change less frequently (like dependency installation)
Use .dockerignore to prevent unnecessary files from being included in the build context
Combine related RUN commands with && to reduce layer count
Consider using COPY --chown to set permissions in one step

Avoid running containers as root - use USER instruction to specify a non-root user
Remove build tools and unnecessary packages from the final image
Scan the final image for vulnerabilities
Set restrictive file permissions
Use multi-stage builds to avoid including build secrets in the final image

Use build arguments for configuration that might change between environments
Leverage build cache efficiently by ordering layers from least to most frequently changing
Consider parallelization in build steps when possible
Set appropriate environment variables like NODE_ENV=production to optimize runtime behavior
Use appropriate healthchecks for the application type with the HEALTHCHECK instruction

Multi-Stage Structure

Use a builder stage for compilation, dependency installation, and other build-time operations

Use a separate runtime stage that only includes what's needed to run the application

Copy only the necessary artifacts from the builder stage to the runtime stage

Use meaningful stage names with the AS keyword (e.g., FROM node:18 AS builder)

Place stages in logical order: dependencies → build → test → runtime

Base Images

Start with official, minimal base images when possible

Specify exact version tags to ensure reproducible builds (e.g., python:3.11-slim not just python)

Consider distroless images for runtime stages where appropriate

Use Alpine-based images for smaller footprints when compatible with your application

Ensure the runtime image has the minimal necessary dependencies

Layer Optimization

Organize commands to maximize layer caching

Place commands that change frequently (like code changes) after commands that change less frequently (like dependency installation)

Use .dockerignore to prevent unnecessary files from being included in the build context

Combine related RUN commands with && to reduce layer count

Consider using COPY --chown to set permissions in one step

Performance Considerations

Use build arguments for configuration that might change between environments

Leverage build cache efficiently by ordering layers from least to most frequently changing

Consider parallelization in build steps when possible

Set appropriate environment variables like NODE_ENV=production to optimize runtime behavior

Use appropriate healthchecks for the application type with the HEALTHCHECK instruction