urbit/CONTRIBUTING.md

Contributing to Urbit

Thank you for your interest in contributing to urbit.

See urbit.org/docs/getting-started for basic orientation and usage instructions.

Fake ships

You may have an identity on the live network, but doing all your development on the live network would be cumbersome and unnecessary. Standard practice in urbit development is to work on a fake ~zod. Fake ships use deterministic keys (derived from the ship address) and don't talk to the live network. They can talk to each other over the local loopback.

To start a fake ship, simply specify the name with -F:

$ urbit -F zod

You can also pass a name for the pier (or ship directory):

$ urbit -F zod -c my-fake-zod

To resume a fake ship, just pass the name of the pier:

$ urbit my-fake-zod

Git practice

Since we use the GitHub issue tracker, it is helpful (though not required) to contribute via a GitHub pull request. If you already know what you are doing, skip down to the Style section.

Start by cloning the repository on your work machine:

$ git clone https://github.com/urbit/urbit

And, additionally, fork the repository on GitHub by clicking the "Fork" button. Add your fork as a remote:

$ git remote add [username] https://github.com/[username]/urbit

and set it as the default remote to push to:

$ git config --local remote.pushDefault [username]

This is good practice for any project that uses git. You will pull upstream branches from urbit/urbit and push to your personal urbit fork by default.

Next, start a new branch to do your work on. Normally you'll want to use the master branch as your starting point:

$ git checkout -b [branch name] master

Now you are free to do your work on this branch. When finished, you may want to clean up your commits:

$ git rebase -i master

Then you can push to your public fork with git push and make a pull request via the GitHub UI.

After your changes are merged upstream, you can delete your branch (via github UI or git push :[branch] remotely, and with git branch -d locally).

Style

The urbit project uses two-space indentation and avoids tab characters. In C code, it should not be too difficult to mimic the style of the code around you, which is just fairly standard K&R with braces on every compound statement. One thing to watch out for is top-level sections in source files that are denoted by comments and are actually indented one level.

Hoon will be a less familiar language to many contributors. More details are forthcoming; for now, the %ford vane (in pkg/arvo/sys/vane/ford.hoon) is some of the highest quality code in the kernel.

Kernel development

Working on either C or non-kernel Hoon should not bring any surprises, but the Hoon kernel (anything under pkg/arvo/sys/) is bootstrapped from a so-called pill, and must be recompiled if any changes are made. This should happen automatically when you make changes, but if it doesn't, the command to manually recompile and install the new kernel is |reset in dojo. This rebuilds from the sys directory in the home desk in %clay.

Currently, |reset does not reload apps like dojo itself, which will still reference the old kernel. To force them to reload, make a trivial edit to their main source file (under the app directory) in %clay.

The kernel and pills

Urbit bootstraps itself using a binary blob called 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), along with a complete copy of the Arvo source.

The procedure for creating a pill is often called "soliding." It is somewhat similar to |reset, but instead of replacing your running kernel, it writes the compiled kernel to a file. The command to solid is:

> .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

Pills are cached at https://bootstrap.urbit.org and are indexed by the first 10 characters of the git SHA1 of the relevant commit, i.e. as git-[sha1].pill. The continuous integration build uploads these pills for any successful build of a commit or pull request that affects the pkg/arvo/sys/ directory.

You can boot from one of these pills by passing the path to an Arvo working copy with -A (and -s for search):

$ git clone https://github.com/urbit/urbit
$ urbit -F zod -sA urbit/pkg/arvo -s my-fake-zod

Pills are also cached in version control via git LFS. 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:

$ git lfs init
$ git lfs pull

What to work on

If you are not thinking of contributing with a specific goal in mind, the GitHub issue tracker is the first place you should look for ideas. Issues are occasionally tagged with a priority and a difficulty; a good place to start is on a low-difficulty or low-priority issue. Higher-priority issues are likely to be assigned to someone -- if this is the case, then contacting that person to coordinate before starting to work is probably a good idea.

There is also a "help wanted" tag for things that we are especially eager to have outside contributions on. Check here first!

Staying in touch

Questions or other communications about contributing to Urbit can go to support@urbit.org.