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Contributing

Thank you for taking the time to contribute to the chisel-releases project. We welcome quality external contributions in the form of Pull Requests or Issues.

Please note that while we acknowledge that there are many conventions and styles, we must strive for consistency and thus your contributions are expected to match the existing codebase, as described by the following guidelines. Any non-conforming proposals will be subject to immediate rejection.

Code of Conduct

This project and everyone participating in it must follow a Code of Conduct. By participating, you are expected to uphold this code.

Canonical Contributor Licence Agreement

Before creating a pull request you should sign the Canonical contributor license agreement. It is the easiest way for you to give us permission to use your contributions.

How to Contribute

Creating Issues

This project's issues can be found here. Everyone is welcome to comment and add value to existing issues.

If you spot a problem or have a feature request, and a related issue doesn't exist yet, then you can open a new issue.

Submitting Code

Code contributions must be submitted in the form of a Pull Request.

Commit Conventions

Please format your commits following the conventional commit style.

See below for some examples of commit messages:

feat: add new archive to ubuntu-24.04 release
test: increase the smoke tests' verbosity
fix(pkg-a): add missing file to pkg-a_slice
ci(linter): add CI job for linting YAML files
chore(test): update pip dependencies for tests
docs: add new section 'Foo' to README.md

Other common best practices are:

  • separate the commit's message subject from the body with a blank line,
  • limit the subject line to 50 characters,
  • do not capitalize the subject line,
  • do not end the subject line with a period,
  • use the imperative mood in the subject line,
  • wrap the body at 72 characters,
  • use the body to explain what and why (instead of how).

Pull Request Etiquette

Once you're ready to open a PR, please make sure you abide by the following rules:

  • you should be branching off a release branch and not main or any other development branch,
  • use the draft mode if your PR is not yet ready to be reviewed,
  • provide good PR descriptions as the project maintainers aren't necessarily familiar with the packages you are slicing,
  • provide proof of testing and testing instructions, when applicable, to help speed up the review process,
  • if you have inter-dependent PRs, make those dependencies explicit in the PRs' descriptions,
  • keep an eye out for CI failures as reviewers will look at your proposal once all checks are green,
  • if possible, use "Labels" to help the maintainers navigate and prioritize their reviews,
  • do not force push once you already have review comments,
  • when needed, update your PR by merging the latest changes from the target branch,
  • you can close a review comment if you applied the proposed change. Otherwise, or when in doubt, you should simply reply and let the reviewers resolve it.

Please note that in order to get merged, PRs must first be approved at least by two project maintainers.

Slicing Debian Packages

If you are slicing Debian packages and thus proposing new slice definitions, make sure you read the following guidelines. They describe the typical process for slicing Debian packages, while also highlighting our expectations with respect to the design of a proper Slice Definitions File.

1. What package are you slicing?

Pull Requests must be holistic! I.e. you should avoid proposing multiple uncorrelated slice definitions in the same Pull Request.

So step 1 is to find the target Debian package you'll be slicing! This is as simple as thinking about the corresponding apt install command. For example, if your installation command looks like apt install <pkg-a>, then pkg-a is your target Debian package and the one your Pull Request shall propose the slice definitions for.

2. Which Ubuntu release(s) are you targeting?

If you're slicing pkg-a for Ubuntu 24.04, then your Pull Request must be created against this repository's ubuntu-24.04 branch.

Why is this important? To enforce consistency across the different chisel releases, every slice definition that is proposed for a given chisel release MUST also be proposed for all newer and still supported chisel releases. For example, in Dec 2023, if you were proposing new slice definitions for ubuntu-22.04, then you had to ensure they also existed (or were being proposed) for ubuntu-23.04, ubuntu-23.10 and ubuntu-24.04, if applicable.

Tip: you can check which Ubuntu releases are still supported via ubuntu-distro-info --supported -r

3. Does a Slice Definitions File (SDF) exist already for that package?

Check if a YAML file with that package's name exists already under the slices folder (e.g. slices/pkg-a.yaml).

If it does, then you'll be editing it. Otherwise, you must create it.

4. What other packages do you need to slice?

Debian packages can have dependencies, so more often than not, you'll need to slice more than one package.

Start by listing which packages you'll need to slice, and remember to double-check if an SDF already exists for those packages too.

Tip: work your way from your target package (e.g. pkg-a) to its dependencies and its dependencies' dependencies...and so on. For example, pkg-a may depend on pkg-b, while the latter may depend on pkg-c and pkg-d. So those will be the packages you must consider for slicing. Here are some useful references from where you can check a package's dependencies:

  • run apt show <pkgName>;
  • go to https://packages.ubuntu.com/<release-adjective>/<pkgName>

5. Get familiar with the packages

While you don't need to be a maintainer or an expert in order to slice a Debian package, you do need to understand the packages' composition and the functionality they offer.

5.1 What architectures is it available for?

Note that in some occasions, a package might have architecture-specific contents, which means your slice definitions must include the {arch: <arch>} content path property.

Tip: the fastest way to check which architectures a package is available for is to simply look it up at https://packages.ubuntu.com/<release-adjective>/<pkgName>.

5.2 What are its contents?

You need to know the contents of the package in order to define the contents of its slices.

Tip: there are multiple ways to look at a package's contents. Here are a few:

  • apt download <pkgName>:<arch>; dpkg-deb -c <pkgName>_*<arch>.deb, or
  • via <https://packages.ubuntu.com/<release-adjective>/<arch>/<pkgName>/filelist>.
5.3 Does it have maintainer scripts?

The functionally relevant parts of the package's maintainer scripts must be reflected by mutation scripts in your slice definitions.

Tip: the best way to explore a package's maintainer scripts is to extract control information from its Deb. E.g. apt download <pkgName>; dpkg-deb -e <pkgName>_.deb control-info. Make sure you pay special attention to the preinst _and postinst scripts if _ exist.

5.4 What does it do?

This is important to know as it will dictate how your slices should be designed. To make slicing a future-proof, sustainable and intuitive experience, we must ensure:

  1. the slice naming convention is consistent across packages and releases. E.g. many packages deliver configuration files, and these are commonly arranged in their own package slice. We must AVOID having different SDFs defining configuration slices with different names (e.g. conf vs config vs configuration...);
  2. the slice name must convey the functionality it delivers! As a rule of thumb:
    • if you're slicing a library package (e.g. libc6), it is acceptable to define the slice names after the type of files it delivers. For example libs or config;
    • if you're slicing an application package, then you should define its slices based on the functionality they deliver. For example:
      • a core slice for delivering the minimal amount of contents that make the package functional, or
      • a debug slice for delivering specific libraries or utilities for application debugging, or
      • a crypto slice for adding optional modules for cryptographic services, and so on.

Tip: here's an example of an SDF whose slice name is driven by the type of content it delivers, and here's another example of an SDF whose slices are designed according to the functionality they deliver

6. Build/edit the Slice Definitions File(s)

Once you know all the above, you have everything you need to write your own slice definitions. When writing, here are a few best practices we recommend:

  • consider readability, so keep a nice and consistent YAML formatting style;
  • provide additional information via comments, whether it is to justify a design decision or to help clarify the functionality being delivered by a slice;
  • use logical sorting for your slices. Sometimes that will result in an alphabetically ordered SDF, some other times it will result in an SDF where the topmost slices are the most relevant ones;
  • do NOT abuse globs! It can be tempting to simply define your slice's contents with something like /usr/lib/**. However, such patterns are too generic and considered a bad practice, as they have the potential to create conflicts between slice definitions files;
    • Tip: when pondering about the use of a glob, consider the following list of acceptable usages:
      • to abstract the architecture name within the path. E.g.: /a/*-b/c instead of /a/x86_64-a/c;
      • to simplify application-specific paths. E.g.: /a/appX/module/** instead of ['/a/appX/module/foo', '/a/appX/module/bar/baz', ...];
      • to deal with upstream version updates. E.g.: /a/b/lib.so.* instead of /a/b/lib.so.1, since an upstream package update could potentially bump this version and break the slice definition.

7. Test your slices before opening a PR

Apart from asserting your slice definitions' formatting, you must also test them before opening a Pull Request.

Every Chisel release supports the functional testing for slices via Spread.

We expect tests to be provided for every slice, so please ensure you include those in your PRs.

Here's how you can create and run tests for your slice definitions:

  1. under tests/spread/integration/, make sure at least one folder matching the package name you're slicing, exists,

  2. inside that folder you must create a task.yaml file. This is where you'll write all the tests for your slide definitions. Please follow the structure from existing examples, providing at least the summary and execute fields inside task.yaml (for other possible fields, please check the Spread docs),

    1. in test/spread/lib/ you'll also find a set of helper functions that you can call from within your task.yaml execution script,

  3. once your test is ready, ensure you have Spread installed (we recommend installing it from source with go install github.com/snapcore/spread/cmd/spread@latest, but there's also a Spread snap) and also ensure you install the necessary requirements to run the tests locally:

    • with Docker:

      • Docker: you can install it via the Snap Store or by following the official instructions
      • QEMU: if testing for multiple architectures, you'll need to install these packages: sudo apt-get install qemu binfmt-support qemu-user-static

      or

    • with LXD:

  4. from the repository's root directory, you can now run

    spread lxd:tests/spread/integration/<pkgA> lxd:tests/spread/integration/<pkgB> ...

    for running the tests for your slices. Additionally, you can also:

    • replace lxd with docker to run the tests on all supported architectures (NOTE: the docker backend might be unable to run tests that perform privileged operations);
    • run spread docker:ubuntu-22.04-amd64 for orchestrating all the tests (not just yours) with Docker, for amd64 only.

8. Open the PR(s)

Once you have your new slice definitions and you have tested them, you're ready to propose them upstream. When opening a Pull Request, consider the above Pull Request Etiquette in order to make for a more efficient review process.