Cloud Native Buildpacks Pack vs Source-to-Image

Cloud Native Buildpacks Pack is a free command-line tool for building applications with buildpacks and rebasing the resulting application images. It is maintained by the Cloud Native Buildpacks project and is also available as a Go library. Buildpacks turn application source code into container images that can run on any cloud. Listed capabilities include caching, automatic source detection, modular buildpacks, support for multiple languages and processes, minimal images, reproducible builds and reuse of community buildpacks. Pack supports multi-architecture builds and multiple build-cache backends, and the project lists build-time software bills of materials in CycloneDX, SPDX and Syft JSON formats. The CLI runs on Linux, macOS and Windows; installation options include package managers, container images, scripts and manual installation. Builds need a containerized environment and a daemon such as Docker or Podman, and some setups may need the local Docker socket mounted. The project documents CircleCI, GitLab Auto DevOps and Tekton integrations, as well as kpack for Kubernetes-native builds and image updates. Pack is Apache-2.0 licensed.

Source-to-Image is a free, Apache-2.0 toolkit for building reproducible container images from source code. It places source in a builder image, lets that container prepare the application, and outputs a ready-to-run image. A documented workflow can build from a Git repository without a Dockerfile. Builder images may provide assemble and run scripts, plus optional scripts for saving artifacts and explaining usage. Compatible builders can reuse artifacts from an earlier output when incremental settings and scripts are supplied. A .s2iignore file filters source files and directories, while .s2i/environment defines build variables that also appear in the output image. S2I can use an OnBuild strategy with images containing Dockerfile ONBUILD instructions. Examples cover Docker, OpenShift, UBI, Ruby, and WildFly. It runs on Linux, macOS, and Windows, with Docker 1.6+ and Go 1.7.1+ listed as dependencies.