Dokku is a production-grade, self-hosted Platform as a Service (PaaS) that manages the full lifecycle of containerized applications. Its architecture is a plugin-based monolith orchestrated by a core Go binary, where every feature (builders, schedulers, proxies, storage, config) is a self-contained plugin that hooks into lifecycle triggers (plugn system). It supports deployment via git push, archives, or Docker images, and can schedule containers locally via Docker or on Kubernetes clusters via its k3s scheduler. The codebase demonstrates high craftsmanship in its plugin architecture and state management. The `common` plugin provides a robust property store, parallel execution engine, and safe command execution utilities that are used across all plugins. The `scheduler-k3s` plugin is a standout, featuring a custom Helm diff engine for previewing infrastructure changes and complex Helm chart generation for Kubernetes resources. The `storage` and `docker-options` plugins contain well-structured parsers for their respective domain-specific languages. While the core Go code is well-structured and heavily tested (Go unit tests, BATS integration tests), the codebase has medium technical drift. The extensive use of shell scripts for plugin triggers introduces fragility, and the Kubernetes scheduler hardcodes specific versions of external tools (cert-manager, KEDA, Traefik) that require manual updates. Despite this, the project is actively maintained with frequent releases, comprehensive migration guides, and a clear deprecation policy, making it a strong example of a long-lived open-source PaaS.
This is the official Heroku buildpack for Python applications. It implements the standard buildpack lifecycle (detect, compile, release, report) to install a Python runtime and manage dependencies using pip, pipenv, poetry, or uv. It handles Django collectstatic, NLTK corpora downloads, user-supplied hooks (pre/post compile), and Heroku CI. The codebase is a collection of modular shell scripts with a consistent library pattern, extensive integration tests via Hatchet/RSpec, and support for multiple Heroku stacks. It is actively maintained, with Dependabot for dependency updates and CI workflows for every commit. The architecture is straightforward: each lifecycle phase is a standalone script that sources reusable libraries from lib/. While the core logic is specific to Heroku's platform, the library functions (e.g., caching, version resolution, build data reporting) demonstrate good shell scripting practices and could be adapted for other build systems.