railpack

Configure and troubleshoot Railpack builds, with emphasis on RAILPACK_* environment variables, railpack.json overlays, build-plan inspection, local CLI installation and usage, and local BuildKit containers. Use for Railpack provider configuration, custom install/build/start commands, Mise or Apt packages, build or runtime variables and secrets, generated-plan debugging, BUILDKIT_HOST errors, or running Railpack from a release or source checkout.

Install
npx skills add 'https://github.com/railwayapp/railpack/tree/main/.'
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main · 21a254fScanned 2026-09-17

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README.md

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Railpack

CI Run Tests

Railpack is a tool for building images from source code with minimal configuration. It is the successor to Nixpacks and incorporates many of the learnings from running Nixpacks in production at Railway for several years.

Getting Started

# Install mise & railpack
curl -sSL https://mise.run | sh
mise install github:railwayapp/railpack@latest

# start BuildKit container & let railpack know about it
docker run --rm --privileged -d --name buildkit moby/buildkit
export BUILDKIT_HOST='docker-container://buildkit'

# create a Next.js app
npm create next-app@latest my-app
cd my-app

# build and run the app!
railpack build .
docker run -p 3000:3000 -it my-app

Railpack automatically detects the project type (Next.js, in this case, but many languages & frameworks are supported!) and generates an optimized container image.

Note: The above steps are for running Railpack locally to experiment and test. If you deploy on Railway, Railpack runs automatically when you push changes to your repository.

Documentation

Full documentation for both operators (platforms, like Railway) and users (developers using Railpack to build their applications) is available at railpack.com.

Contributing

Railpack is open source and open to contributions. See the CONTRIBUTING.md file for more information.