Image Extension Specification

Image extensions emit Dockerfile snippets applied by the `extender` lifecycle binary to the build and/or run image. Share the buildpack surface (extension.toml, bin/detect, bin/generate) but produce Dockerfile output instead of layers — enabling base-image customization (apt packages, native libs) inside a buildpacks workflow.

Image Extension Specification is one of 7 APIs that buildpacks-io publishes on the APIs.io network.

Tagged areas include Cloud Native Buildpacks, Image Extension, Dockerfile, and Specification. The published artifact set on APIs.io includes API documentation.

API entry from apis.yml

apis.yml Raw ↑
aid: buildpacks-io:image-extension-spec
name: Image Extension Specification
tags:
- Cloud Native Buildpacks
- Image Extension
- Dockerfile
- Specification
humanURL: https://github.com/buildpacks/spec/blob/main/image_extension.md
properties:
- url: https://github.com/buildpacks/spec/blob/main/image_extension.md
  type: Documentation
- url: https://github.com/buildpacks/spec
  type: Repository
description: Image extensions emit Dockerfile snippets applied by the `extender` lifecycle binary to the
  build and/or run image. Share the buildpack surface (extension.toml, bin/detect, bin/generate) but produce
  Dockerfile output instead of layers — enabling base-image customization (apt packages, native libs)
  inside a buildpacks workflow.