urbit/CONTRIBUTING.md

Workflow

Before beginning any unit of work, you should have a GitHub issue detailing the scope of the work. This could be an issue someone else filed and has been assigned to you (or you've assigned to yourself) or a new issue you filed specifically for this unit of work. As much as possible, discussion of the work should take place in the issue. When this is not possible, please update the issue with relevant details from any offline conversations. Each issue should provide a clear and thorough history of the work from inception to completion.

Issues

The GitHub tracker is our canonical source of truth around issues, bugs, performance problems and feature requests. If you encounter any issues when developing on Urbit, feel free to submit a report about it here.

A good bug report, description of a crash, etc., should ideally be reproducible, with clear steps as to how another developer can replicate and examine your problem. That said, this isn't always possible -- some bugs depend on having created a complicated or unusual state, or can otherwise simply be difficult to trigger again.

Your issue should thus at a minimum be informative. The best advice here is probably "don't write bad issues," where "bad" is a matter of judgment and taste. Issues that the maintainers don't judge to be sufficiently useful or informative may be closed.

Feature requests are welcome, but they should include sufficient detail and explanation, as well as a discussion of perceived benefits one could expect from them. "It would be cool if.." probably does not, in itself, constitute a good feature request; instead, try to be specific about what you're requesting, and what your desired feature would accomplish.

Feature Branch Names

Every branch that you intend to put up for review must adhere to the form i/<N>/<...>, where <N> is the number of the issue that the branch corresponds to and <...> is an optional short description of the branch to aid in readability. If <...> is omitted, the / should be omitted as well, which makes i/<N> a well-formed branch name. These feature branches should be based off of develop.

Commits

Commits should generally be relevant, atomic, and have descriptions formatted in the following manner:

component: short description

long description

The 'component' is a short prefix of what area of the codebase the commit applies to. If a commit patches %gall, for example, the description should be prefixed by 'gall'. If it touches :aqua, it should be prefixed by 'aqua'. If it touches multiple components, then separate these by commas, e.g. "gall, aqua, ph" -- but note that this may be a warning that too many changes are being packed into a single commit. The 'component' and 'short description' combined should be no more than 50 characters.

Every individual commit should at a minimum be in a compiling and runnable state. Broken commits or commits simply marked "wip" are not allowed. If you need to clean up the commits in your branch, you can soft reset to an earlier state and recommit with better metadata (or if the change is small enough, squash to one good commit at the end).

A lengthier description is encouraged, but is not always strictly required. You should use the longer description to give any useful background on or motivation for the commit, provide a summary of what it does, link to relevant issues, proposals, or other commits, and so on.

Here is an example of our commit format, taken from a commit in the history:

zuse: remove superfluous 'scup' and 'culm' types.

%zuse includes definitions for 'scup' and 'culm', both of which are superfluous. 'scup' is simply (pair ship desk) and is used only in the definition of 'culm', a tagged union in which three of the four branches are commented out (i.e. are unused).

This commit deletes 'scup' and 'culm' and refactors what little code made use of them.

Note that the short description is prefixed by zuse:, which is what the commit touches. Otherwise it just includes a summary of the change.

Here's another example:

build: give arvo a high priority

0bdced981e introduced the 'arvo-ropsten' derivation. Attempting to install both 'arvo' and 'arvo-ropsten' via nix-env will result in a priority error; this assigns a higher priority to 'arvo' to resolve the conflict.

Fixes #1912.

Note that it cites a previous relevant commit, 0bdced981e4, in its summary, and also points at the issue that it resolves.

When we say commits should be "atomic", we mean with respect to some distinct logical unit, e.g. a type definition used across many files, or a single file, or just a single function in a single file. Commits should be atomic at the level of code, not of entire features. You don't have to squash your commits into a single one that captures everything you're trying to do -- the history will never make for pleasant bedtime reading, so focus instead on making your commits useful for tools like git-blame and git-bisect.

Your contribution must apply cleanly to develop in order to be considered mergeable. You may want to regularly rebase your changes onto develop in order to both clean up any intermediate "development" commits you make and to ensure that you're up to date.

Pull Requests and Merges

When your work is ready for review, open a pull request, making sure to link to the tracking issue in the description, which should be formatted as follows (where <N> is the number of this work's tracking issue):

### Description

Resolves #<N>.

Thoroughly describe the changes made.

### Related

Reference any related issues, links, papers, etc. here.

Tests will run automatically via GitHub Actions when you open a pull request or push new commits to an existing pull request.

Once you've collected and addressed feedback, tests are passing, and your PR has been approved, merge the pull request.

Note: If you are merging into develop, you must be syncing OTAs from ~binnec-dozzod-marzod which gets the tip of develop deployed to it. If your merge breaks binnec it's your responsibility to alert people and fix it. Your PR is shipped when it's successfully been deployed to ~binnec and picked up by your personal ship. If you're merging on behalf of an external developer, this is also your responsibility.

If you properly included the "Resolves #N." directive in the pull request description, merging will automatically close the tracking issue associated with the pull request.

Code style

Hoon will be a less familiar language to many contributors. We've published some style guidelines for Hoon, but above all you should try to mimic the style of the code around you. With regards to the style used throughout the codebase: the more recently the code was written, the more standard and accepted its style is likely to be.

Kernel Development and Pills

Urbit bootstraps itself from a pill (you can see it being fetched from bootstrap.urbit.org on boot). This is the compiled version of the kernel (which you can find in the sys directory of [Arvo][arvo]), along with a complete copy of the Arvo source.

You can find the latest solid pill, as well as the latest so-called brass and ivory pills, in the bin/ directory at the repository root.

Any contribution that touches the kernel (i.e., anything in pkg/arvo/sys), should be accompanied by an updated solid pill. Pills are tracked in the repository via git LFS.

$ git lfs init
$ git lfs pull

The +solid command is used to write the compiled kernel to a file.

> .urbit/pill +solid

When the compilation finishes, your pill will be found in the [pier]/.urb/put/ directory as urbit.pill.

You can boot a new ship from your local pill with -B:

$ urbit -F zod -B path/to/urbit.pill my-fake-zod

Release pills, i.e. those corresponding to vere releases, are cached at https://bootstrap.urbit.org and are indexed by the vere version number, e.g. urbit-0.8.2.pill.

Whenever you make a contribution to the kernel, please create a new solid pill via:

sh/update-solid-pill

You should include the updated pill in the same commit that updates the source.

Development Environment

Although you likely have an identity on the live network, developing on the live network is high-risk and largely unnecessary. Instead, standard practice is to work on a fake ship. Fake ships use deterministic keys derived from the ship's address, don't communicate on the live network, and can communicate with other fake ships over the local loopback.

Boot a New Fake Ship

To boot a new fake ship, pass the -F flag and a valid Urbit ship name to urbit:

$ bazel build :urbit
$ ln -s bazel-bin/pkg/vere/urbit urbit
$ ./urbit -F <ship>

By default, booting a fake ship will use the same pill that livenet ships use, which leads to a non-trivial boot time on the order of tens of minutes. However, using a development specific "solid" pill reduces this time to a couple minutes.

To boot using the solid pill, download or create one as described in the Kernel Development and Pills section above and then run the following:

$ ./urbit -F <ship> -B solid.pill

Launch an Existing Fake Ship

To launch an existing fake ship, supply the pier (the ship directory), which is simply the name of the ship¹, to urbit:

$ ./urbit <ship>

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1. Unless you specified the pier name using the -c flag. ↩︎