Git Usage#
Note
For detailed information on Git and OpenBeagle GitLab checkout the official help page.
Note
Most of these guidelines were taken from the
BioPython project
to be used for BeagleBoard Docs (and other OpenBeagle-hosted project) development using
git. Please provide feedback via the
site-feedback category on our forum.
This document is meant as an outline of the way the BeagleBoard Docs project is developed. It should include all essential technical information as well as typical procedures and usage scenarios. It should be helpful for core developers, potential documentation contributors, testers and everybody interested in BeagleBoard Docs and other BeagleBoard projects.
Relevance#
This page is about using git for tracking and submitting changes.
If you have found a problem with any BeagleBoard project, and think you know how to
fix it, then we suggest following the simple route of filing an
issue and describe
your fix. Ideally, you would upload a patch file showing the differences
between the latest version of BeagleBoard project (from our repository) and your
modified version. Working with the command line tools diff and patch
is a very useful skill to have, and is almost a precursor to working
with a version control system.
This page provides a technical introduction into git usage including
required software and integration with OpenBeagle. If you want to start
contributing to BeagleBoard projects, you definitely need to install git and learn
how to obtain a branch of the OpenBeagle project to which you want to contribute.
If you want to share your changes easily with others, you should also
sign up for an OpenBeagle (BeagleBoard Gitlab)
account and read the corresponding section of the manual. Finally, if you are
engaged in one of the collaborations on experimental BeagleBoard projects,
you should look also into code review and branch merging.
Installing git#
You will need to install git on your computer. git
is available for all major operating systems. Please use the appropriate
installation method as described below.
git is now packaged in all major Linux distributions. You should find it
in your package manager.
Ubuntu/Debian
You can install git from the git-core package. e.g.,
sudo apt-get install git-core
You’ll probably also want to install the following packages: gitk, git-gui, and git-doc
Redhat/Fedora/Mandriva
git is also packaged in rpm-based linux distributions.
dnf install gitk
should do the trick for you in any recent Fedora/Mandriva or derivatives
Download the .dmg disk image from http://code.google.com/p/git-osx-installer/
Note
It is worthwhile to consider using Linux at least inside of a virtual machine (VM).
Download the official installers from Windows installers
Testing your git installation#
If your installation succeeded, you should be able to run
$ git --help
in a console window to obtain information on git usage. If this fails, you should refer to official git documentation for troubleshooting.
Creating an OpenBeagle account (optional)#
Note
OpenBeagle runs an open source instance of GitLab Community Edition.
Once you have git installed on your machine, you can obtain the code and
start developing. Since the code is hosted by OpenBeagle, however, you may
wish to take advantage of the site’s offered features by signing up for
an OpenBeagle account. While an OpenBeagle account is completely optional and not
required for obtaining the BeagleBoard Docs code or participating in
development, an OpenBeagle account will enable all other BeagleBoard Docs developers
to track (and review) your changes to the code base, and will help you
track other developers’ contributions. This fosters a social,
collaborative environment for the BeagleBoard community.
If you don’t already have an OpenBeagle account, you can create one here. Once you have created your account, upload an SSH public key by clicking on SSH and GPG keys <https://openbeagle.org/-/profile/keys> after logging in. For more information on generating and uploading an SSH public key, see this OpenBeagle guide on SSH keys.
Working with the source code#
In order to start working with the BeagleBoard Docs source code, you need to
obtain a local clone of our git repository. In git, this means you will
in fact obtain a complete clone of our git repository along with the
full version history. Thanks to compression, this is not much bigger
than a single copy of the tree, but you need to accept a small overhead
in terms of disk space.
There are, roughly speaking, two ways of getting your own version of the source code tree:
by simply “cloning” the repository to your own computer,
or by “forking” the repository on OpenBeagle.
They’re not that different, in fact both will result in a directory containing a customizable full copy of the repository. However, if you have a OpenBeagle account, you can make your repository a publicly visible branch of the project. If you do so, other people will be able to easily review your code, make their own branches from it or merge it back to the trunk.
Using branches on OpenBeagle is the preferred way to work on updates to
BeagleBoard Docs, so it’s useful to learn it and use it even if you think
your changes are not for immediate inclusion into the main trunk of
BeagleBoard Docs. But even if you decide not to use OpenBeagle, you can always
change this later using the .git/config file in your clone. For
simplicity, we describe these two possibilities separately.
Cloning BeagleBoard Docs directly#
Getting a copy of the repository (called “cloning” in git terminology)
without an OpenBeagle account is very simple:
git clone https://openbeagle.org/docs/docs.beagleboard.io.git
This command creates a local copy of the entire BeagleBoard repository on your machine (your own personal copy of the official repository with its complete history). You can now make local changes and commit them to this local copy (although we advise you to use named branches for this, and keep the main branch in sync with the official BeagleBoard code).
If you want other people to see your changes, however, you must publish your repository to a public server yourself (e.g. OpenBeagle, Github, GitLab).
Forking BeagleBoard with your OpenBeagle account#
If you are logged in to OpenBeagle, you can go to the BeagleBoard Docs repository page:
https://openbeagle.org/docs/docs.beagleboard.io
and click on the button named ‘Fork’. This will create a fork (basically a copy) of the official BeagleBoard Docs repository, publicly viewable on OpenBeagle, but listed under your personal account. It should be visible under a URL that looks like this:
https://openbeagle.org/yourusername/docs.beagleboard.io
Since your new BeagleBoard Docs repository is publicly visible, it’s considered good practice to change the description and homepage fields to something meaningful (i.e. different from the ones copied from the official repository).
If you haven’t done so already, setup an SSH key and upload it to OpenBeagle for authentication.
Now, assuming that you have git installed on your computer, execute the
following commands locally on your machine. This “url” is given on the
OpenBeagle page for your repository (if you are logged in):
git clone [email protected]:yourusername/docs.beagleboard.io.git
Where yourusername, not surprisingly, stands for your OpenBeagle username. You have just created a local copy of the BeagleBoard Docs repository on your machine.
You may want to also link your branch with the official distribution (see below on how to keep your copy in sync):
git remote add upstream https://openbeagle.org/docs/docs.beagleboard.io
If you haven’t already done so, tell git your name and the email address you are using on OpenBeagle (so that your commits get matched up to your OpenBeagle account). For example,
git config --global user.name "David Jones" config --global user.email "[email protected]"
Making changes locally#
Now you can make changes to your local repository - you can do this offline, and you can commit your changes as often as you like. In fact, you should commit as often as possible, because smaller commits are much better to manage and document.
First of all, create a new branch to make some changes in, and switch to it:
git checkout -b demo-branch
To check which branch you are on, use:
git branch
Let us assume you’ve made changes to the file boards/beagleplay/01-introduction.rst Try this:
git status
So commit this change you first need to explicitly add this file to your change-set:
git add boards/beagleplay/01-introduction.rst
and now you commit:
git commit -m "added updates X in BeaglePlay introduction"
Your commits in git are local, i.e. they affect only your working branch
on your computer, and not the whole BeagleBoard Docs tree or even your fork on
OpenBeagle. You don’t need an internet connection to commit, so you can do
it very often.
Pushing changes to OpenBeagle#
If you are using OpenBeagle, and you are working on a clone of your own branch, you can very easily make your changes available for others.
Once you think your changes are stable and should be reviewed by others, you can push your changes back to the OpenBeagle server:
git push origin demo-branch
Note
This will not work if you have cloned directly from the official BeagleBoard branch, since only the core developers will have write access to the main repository.
Merging upstream changes#
We recommend that you don’t actually make any changes to the main branch in your local repository (or your fork on OpenBeagle). Instead, use named branches to do any of your own work. The advantage of this approach it is the trivial to pull the upstream main (i.e. the official BeagleBoard branch) to your repository.
Assuming you have issued this command (you only need to do this once):
git remote add upstream https://openbeagle.org/docs/docs.beagleboard.io
Then all you need to do is:
git checkout main
git pull upstream main
Provided you never commit any change to your local main branch, this should always be a simple fast forward merge without any conflicts. You can then deal with merging the upstream changes from your local main branch into your local branches (and you can do that offline).
If you have your repository hosted online (e.g. at OpenBeagle), then push the updated main branch there:
git push origin main
Submitting changes for inclusion in BeagleBoard Docs#
If you think you changes are worth including in the main BeagleBoard Docs
distribution, then file a report on our issue
tracker, and include a link to your updated branch (i.e. your branch on
OpenBeagle, or another public git server). You could also attach a patch to the bug.
If the changes are accepted, one of the BeagleBoard Docs developers will have to check
this code into our main repository.
On OpenBeagle itself, you can inform keepers of the main branch of your changes by sending a ‘merge request’ from the page of your branch.
If other things have happened since you began your work, it may require merging when applied to the official repository’s main branch. In this case, we might ask you to help by rebasing your work:
git fetch upstream
git checkout demo-branch
git rebase upstream/main
Hopefully, the only changes between your branch and the official repository’s
main branch are trivial and git will handle everything automatically.
If not, you would have to deal with the clashes manually. If this works,
you can update the merge request by replacing the existing (pre-rebase)
branch:
git push origin demo-branch
If however the rebase does not go smoothly, give up with the following command (and hopefully the BeagleBoard Docs developers can sort out the rebase or merge for you):
git rebase --abort
Evaluating changes#
Since git is a fully distributed version control system, anyone can
integrate changes from other people, assuming that they are using
branches derived from a common root. This is especially useful for
people working on new features who want to accept contributions from
other people.
This section is going to be of particular interest for the BeagleBoard Docs core developers, or anyone accepting changes on a branch.
For example, suppose Jason has some interesting changes on his public repository:
https://openbeagle.org/jkridner/docs.beagleboard.io
You must tell git about this by creating a reference to this remote
repository:
git remote add jkridner https://openbeagle.org/jkridner/docs.beagleboard.io
Now we can fetch all of Jason’s public repository with one line:
git fetch jkridner
Now we can run a diff between any of our own branches and any of Jason’s branches. You can list your own branches with:
git branch
Remember the asterisk shows which branch is currently checked out.
To list the remote branches you have setup:
git branch -r
For example, to show the difference between your main branch and Jason’s main branch:
git diff main jkridner/main
If you are both keeping your main branch in sync with the upstream BeagleBoard repository, then his main branch won’t be very interesting. Instead, try:
git diff main jkridner/awesomebranch
You might now want to merge in (some) of Jason’s changes to a new branch on your local repository. To make a copy of the branch (e.g. awesomebranch) in your local repository, type:
git checkout --track jkridner/awesomebranch
If Jason is adding more commits to his remote branch and you want to update your local copy, just do:
git checkout awesomebranch # if you are not already in branch awesomebranch
If you later want to remove the reference to this particular branch:
$ git branch -r -d jkridner/awesomebranch
Deleted remote branch jkridner/awesomebranch (#######)
Or, to delete the references to all of Jason’s branches:
$ git remote rm jkridner
$ git branch -r
upstream/main
origin/HEAD
origin/main
Alternatively, from within OpenBeagle you can use the fork-queue to cherry pick commits from other people’s forked branches. While this defaults to applying the changes to your current branch, you would typically do this using a new integration branch, then fetch it to your local machine to test everything, before merging it to your public working branch.
Additional Resources#
There are a lot of different nice guides to using git on the web: