created_at2023-05-26 16:01:59.296926
updated_at2024-06-05 17:02:55.615846
descriptionWelcome! Please see for more information!
Alex Evanczuk (alexevanczuk)





CI Security Audit

A 100% Rust implementation of packwerk, a gradual modularization platform for Ruby.


Serve as a drop-in replacement for packwerk on most projects

  • Currently can serve as a drop-in replacement on Gusto's extra-large Rails monolith
  • This is a work in progress! Please see Verification for instructions on how to verify the output of packs is the same as packwerk.

Run 20x faster than packwerk on most projects

  • Currently ~10-20x as fast as the ruby implementation. See
  • Your mileage may vary!
  • Other performance improvements are coming soon!

Support non-Rails, non-zeitwerk apps

  • Currently supports non-Rails apps through an experimental implementation
  • Uses the same public API as packwerk, but has different behavior.
  • See for more info

Usage and Documentation

Once installed and added to your $PATH, just call pks to see the CLI help message and documentation.

Welcome! Please see for more information!

Usage: pks [OPTIONS] <COMMAND>

  greet                           Just saying hi
  create                          Create a new pack
  check                           Look for violations in the codebase
  check-contents                  Check file contents piped to stdin
  update                          Update package_todo.yml files with the current violations
  validate                        Look for validation errors in the codebase
  add-dependency                  Add a dependency from one pack to another
  check-unnecessary-dependencies  Check for dependencies that when removed produce no violations.
  lint-package-yml-files          Lint package.yml files
  expose-monkey-patches           Expose monkey patches of the Ruby stdlib, gems your app uses, and your application itself
  delete-cache                    `rm -rf` on your cache directory, default `tmp/cache/packwerk`
  list-packs                      List packs based on configuration in packwerk.yml (for debugging purposes)
  list-included-files             List analyzed files based on configuration in packwerk.yml (for debugging purposes)
  list-definitions                List the constants that packs sees and where it sees them (for debugging purposes)
  help                            Print this message or the help of the given subcommand(s)

      --project-root <PROJECT_ROOT>  Path for the root of the project [default: .]
  -d, --debug                        Run with performance debug mode
  -e, --experimental-parser          Run with the experimental parser, which gets constant definitions directly from the AST
      --no-cache                     Run without the cache (good for CI, testing)
  -p, --print-files                  Print to console when files begin and finish processing (to identify files that panic when processing files concurrently)
  -h, --help                         Print help
  -V, --version                      Print version



Using with VSCode/RubyMine Extension

packwerk has a VSCode Extension:

It also has a RubyMine Extension:

Using the extension with packs is straightforward and results in a much more responsive experience.


  • Follow instructions to install packs
  • Follow the configuration directions to configure the extension to use packs instead of the ruby gem by setting the executable to packs check


As packs is still a work-in-progress, it's possible it will not produce the same results as the ruby implementation (see Not Yet Supported). If so, please file an issue – I'd love to try to support your use case!


  • Follow the directions above to install packs
  • Run packs update
  • Confirm the output of git diff is empty
  • Please file an issue if it's not!

New to Rust?

Me too! This is my first Rust project, so I'd love to have feedback, advice, and contributions!

Rust is a low-level language with high-level abstractions, a rich type system, with a focus on memory safety through innovative compile-time checks on memory usage.

If you're new to Rust, don't be intimidated! has tons of great learning resources.

If you'd like to contribute but don't know where to start, please reach out! I'd love to help you get started.

Not yet supported

  • custom inflections
  • custom load paths
  • extensible plugin system

Behavioral differences

There are still some known behavioral differences between packs and packwerk. If you find any, please file an issue!

  • package_paths must not end in a slash, e.g. packs/*/ is not supported, but packs/* is.
  • A ** in package_paths is supported, but is not a substitute for a single *, e.g. packs/** is supported and will match packs/*/*/package.yml, but will not match packs/*/package.yml. packs/* must be used to match that.

Default Namespaces

packs supports Zeitwerk default namespaces. However, since it doesn't have access to the Rails runtime, you need to explicitly specify the namespaces in packwerk.yml.

For example, if you're using packs-rails and automatic_namespaces to configure your default namespaces, and you have

  • packs/foo/app/models/bar.rb which is configured to define Foo::Bar
  • packs/foo/app/domain/baz.rb which is configured to define Foo::Baz

You'll need to specify the default namespaces in packwerk.yml like so:

  packs/foo/app/models: "::Foo"
  packs/foo/app/domain: "::Foo"

Enforcement Globs Ignore

enforcement_globs_ignore can be used to specify gitignore-style rules for not enforcing violations.


# packs/product_services/serv1/foo/package.yml
enforce_privacy: true
enforce_visibility: true

- enforcements:
  - privacy
  - visiblity
  - "**/*"
  # Enforce incoming privacy and visibility violation references _only_ in `packs/product_services/serv1/**/*`
  - "!packs/product_services/serv1/**/*"
# packs/pack2/package.yml
enforce_dependencies: true
# not required because of the below enforcement_globs_ignore
# - packs/pack1 
# required because of the enforcement_globs_ignore exception line 
  - packs/pack3 

- enforcements:
  - dependency
  - "**/*"
  # Enforce outgoing dependency violation references _only_ to `packs/pack3/**/*`
  - "!packs/pack3/**/*"




  • Current (@gmcgibbon, @rafaelfranca), and Ex-Shopifolks (@exterm, @wildmaples) for open-sourcing and maintaining packwerk
  • Gusties, and the Ruby/Rails Modularity Slack Server, for continued feedback and support
  • @mzruya for the initial implementation and Rust inspiration
Commit count: 602

cargo fmt