Miget Buildpacks

Miget Buildpacks, powered by migetpacks, automatically detect your application’s language, version, and dependencies to produce optimized container images. You get production-ready builds with zero configuration. migetpacks handles language detection, dependency installation, and multi-stage Dockerfile generation so you can focus on your code.

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Supported Languages

Miget Buildpacks support 14 languages and their ecosystems:

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How It Works

Miget Buildpacks run through four phases to turn your source code into a container image.

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1. Language Detection

migetpacks scans your repository for marker files to determine which language and framework your application uses. For example, a package.json file triggers the Node.js buildpack, while a go.mod file triggers the Go buildpack.

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2. Version Detection

Once the language is identified, migetpacks reads version files to determine the exact runtime version you need:

• Node.js: .nvmrc, .node-version, package.json engines field
• Python: .python-version, runtime.txt
• Ruby: .ruby-version, Gemfile
• Go: go.mod directive

Versions are normalized automatically so you can use shorthand notation (e.g., 20 resolves to the latest Node.js 20.x release).

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3. Dockerfile Generation

migetpacks generates an optimized multi-stage Dockerfile using official Docker Hub base images (node, python, ruby, golang, etc.). The generated Dockerfile includes:

• Dependency layer caching - dependencies are installed in a separate stage so rebuilds only rerun when your lockfile changes
• Multi-stage builds - build tools stay out of the final image, reducing size and attack surface
• Official base images - every build starts from trusted, maintained upstream images

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4. Build and Push

The generated Dockerfile is built with BuildKit and the resulting image is pushed to the container registry for deployment.

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Using Miget Buildpacks

During app creation or when changing your deployment source, select Auto detection (Miget Buildpacks) as the Builder Type. This is the default builder type for new applications. You can optionally override the default run command if your application requires a custom start command.

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Advanced Settings

In the Advanced tab, you can configure additional build and deployment options:

• Project Path - For monorepo setups where your application code is in a subdirectory
• Pre-Deploy Command - A command to run before deployment, such as database migrations (e.g., rails db:migrate)
• Post-Deploy Command - A command to run after successful deployment, such as seeding data or cache warming (e.g., npm run seed)
• Docker Hardened Images (DHI) - Toggle to build with distroless runtime images for minimal attack surface

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Docker Hardened Images (DHI)

When you enable Use Docker Hardened Images in the Advanced tab, your application runs on distroless runtime images from Docker that provide:

• Minimal attack surface
• No shell or package manager in the final image
• Smaller image size
• Available for most supported languages

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Configuration

Miget Buildpacks support several configuration options, all optional:

• Version files - Language-specific files like .nvmrc, .python-version, or .ruby-version to pin your runtime version
• Procfile - Define process types and their start commands (e.g., web: node server.js)
• app.json - Application manifest for additional build and runtime configuration
• Environment variables - Set build-time and runtime environment variables to customize your build
• Custom run command - Override the default start command in the Miget dashboard
• Pre/Post-Deploy commands - Run tasks before or after deployment in the Advanced tab

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Advantages

• Zero configuration - Push your code and migetpacks handles the rest
• Official upstream images - Builds use trusted Docker Hub images for every language
• Smart dependency detection - Automatically identifies your package manager and lockfile
• Multi-stage builds with layer caching - Fast rebuilds and small final images
• Consistent, reproducible builds - The same source always produces the same image

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