Build Dockerfiles visually. Select a preset template or configure each instruction manually, then generate a production-ready Dockerfile you can copy into your project.
Presets:
Build Options
Labels (LABEL)
Environment Variables (ENV)
Copy Files (COPY)
Run Commands (RUN)
Expose Ports (EXPOSE)
Generated Dockerfile
# Click "Generate Dockerfile" or press Ctrl+Enter
How to Use the Dockerfile Builder
Start by selecting a preset template for your language or framework, then customize each instruction. You can add environment variables, labels, COPY instructions, RUN commands, and exposed ports. Toggle multi-stage builds to create optimized production images with separate build and runtime stages.
Dockerfile Best Practices
Use specific tags: Avoid latest — pin versions like node:20-alpine
Copy dependency files first: Leverage layer caching by copying package.json before source code
Chain RUN commands: Combine with && to reduce image layers
Multi-stage builds: Separate build dependencies from runtime to minimize image size
Use .dockerignore: Exclude node_modules, .git, and other unnecessary files
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A Dockerfile is a text file containing instructions that Docker uses to build an image. Each instruction (FROM, RUN, COPY, ENV, EXPOSE, CMD, ENTRYPOINT) creates a layer in the image. Dockerfiles automate the process of creating reproducible container images for your applications.
What is a multi-stage Docker build?▼
A multi-stage build uses multiple FROM statements in a single Dockerfile. The first stage typically compiles or builds your application, and the final stage copies only the built artifacts into a smaller base image. This dramatically reduces the final image size by excluding build tools, source code, and intermediate files.
What is the difference between CMD and ENTRYPOINT?▼
CMD sets the default command that runs when a container starts, but it can be overridden from the command line. ENTRYPOINT sets the main executable for the container and is harder to override. When both are used together, CMD provides default arguments to the ENTRYPOINT command. Use ENTRYPOINT for the main process and CMD for default flags.
What base image should I use?▼
Use slim or Alpine variants for smaller images: node:20-alpine, python:3.12-slim, golang:1.22-alpine. Alpine images are around 5MB compared to 100MB+ for full images. For production, use specific version tags (not "latest") to ensure reproducible builds. Use distroless images from Google for maximum security.
How do I optimize Docker layer caching?▼
Order instructions from least to most frequently changing. Copy dependency files (package.json, requirements.txt) before source code and run install commands first. This way, dependency layers are cached and only rebuilt when dependency files change. Combine related RUN commands with && to reduce layers, and use .dockerignore to exclude unnecessary files.
Keyboard Shortcuts
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