View source for Git

= What is Git? =

[http://git-scm.com/ Git] is a ''[https://en.wikipedia.org/wiki/Distributed_version_control distributed]'' '''[https://en.wikipedia.org/wiki/Version_control version control system]''' (VCS) originally developed by Linus Torvalds for managing Linux source code without requiring a central server. It is also the primary VCS used by the [http://www.gnome.org Gnome] and [http://www.freedesktop.org Free Desktop] projects. You can get the latest version for your system and read a rich variety of online documentation at [http://git-scm.com/ Git's Home]. In particular, ''Pro Git'' by Scott Chacon is available in several languages for free online reading at [http://git-scm.com/book Git Book], where you can also download the English version as a PDF, ebook, or mobi.

If you know nothing about version control, that doesn't matter. Just read [http://git-scm.com/book/en/v2/Getting-Started-About-Version-Control Getting Started - About Version Control]. There in the left column you can select your language. 

Another good place to start is [https://help.github.com/articles/good-resources-for-learning-git-and-github/ Good Resources for Learning Git and GitHub] - not only if you want to use GitHub for [[#Pull Requests]].

 git help
will give you a list of usual commands and
 git help <command>
will show you the manual page of that command.

There are several GUIs available for git, e.g.:
* git gui
* gitk (shows the history)
* [http://www.sourcetreeapp.com/ SourceTree] for Windows or Mac
and most IDEs have plugins for it.

= What has that to do with Gnucash? =

We are using Git to manage our code and documentation sources.

Our '''public repositories''' are ''mirrored on Github'': for [https://github.com/Gnucash/gnucash code], [https://github.com/Gnucash/gnucash-docs documentation] and for the [https://github.com/Gnucash/gnucash-htdocs website]. These are updated from the ''primary repository'' by commit hooks, so barring technical problems changes appear in these repositories within a few seconds of being committed to the primary.

<tt>code.gnucash.org</tt> is the server that hosts the '''canonical git repository''', wiki, [[Mailing Lists]], automated win32 builds, and the nightly builds  of the [http://code.gnucash.org/docs/ documentation and API docs] (via [[Doxygen]]) for both [[#Branches|branches]].

= Using the Github Repository =

== Non-Committers ==

If you are new to using git, you may find it useful to read [[Git_For_Newbies|Git For Newbies]] for more information about specific git commands and how they are used in the process of modifying GnuCash.

=== Set-Up ===
Just clone the repository as usual:

  git clone https://github.com/Gnucash/gnucash.git
:;other URLs: https://github.com/Gnucash/gnucash-docs (documentation)
::https://github.com/Gnucash/gnucash-htdocs (website)
::See https://github.com/Gnucash for further repos e.g. with OS/distro specific build scripts.

==== Branches ====
There are 2 important branches in most of our repositories:
:;master: is the default branch in git. ''New features'' and their documentation should be based on this branch.
:;maint: ''Bugfixes'', ''translations'', improvements of the ''documentation'' should usually be applied on this branch.

In your ''local working dir'' you should checkout one of them, e.g.:
 git checkout master

When you have patches in master, use 

  git format-patch origin/master..master

(or <tt>git diff</tt>) in the root directory of your local repository to prepare them; then add the patchfile as an attachment to the appropriate bug report.

==== GitHub ====
If you have a Github account, you could as well
# use Github's '''fork''' feature to set up a '''clone''' on GitHub. And then
# clone from that repository instead (note that this is your personal ''read-write enabled'' clone):
#: <pre>git clone git@github.com:<YOUR-GITHUB-USERNAME>/gnucash.git</pre>
#: Note that this clone command takes the ''URL in a different format''.
# With this form you will be able to push your local changes to your GitHub account as usual:
#: <pre>git push origin master</pre>

{|cellpadding="20"
| Depending on your access rights you might continue with ...
||[[#Pull Requests]]
||[[#Committers]]
|}

=== Patches ===
If you're going to be submitting patches:
* Create a branch to work in:
** '''Bug fixes''' should branch off of ''maint'' unless the bug applies only to the unstable version.
** '''New features''' must branch off of ''master''.
The following example is for a new feature; ''substitute <tt>maint</tt> for <tt>master</tt> if you're doing a bug-fix''.
* Use a particular working branch for ''only one'' bug or feature. This will make it much easier to make changes and generate new patches should that prove necessary.
  git checkout master
  git branch working-branch
* Rebase your working branch onto the target branch often so that you stay in sync:
  git rebase master working-branch
* Open a bug in Bugzilla to attach your patch to if one doesn't already exist.
* Write good commit messages in which the bug number and summary are the first line. Skip one line, then describe the patch. For example:
  [Bug 673193] - Possible Register migration to TreeView
  
  Update the old register rewrite branch to work with the currently-released Gtk2.
* Use <tt>git rebase -i</tt> as necessary to make a clean series of patches for complex changes.
* Be sure to do a fresh rebase from the target branch and a make check to ensure that everything works
* Use <tt>git format-patch</tt> to create the actual patches from your commits:
  git rebase master working-branch
  git format-patch master
* Attach the resulting patch(es) to the bug report.
* If a committer asks you to make changes, revise your original commit and make a new patch. Don't submit a patch to be applied on top of an old one. <tt>[https://www.kernel.org/pub/software/scm/git/docs/git-rebase.html git-rebase] -i</tt> can be very helpful if you have a series of patches.

=== Pull Requests ===
If you prefer, you can use a GitHub Pull Request instead of attaching a patch to a bug.
* Fork the Gnucash/gnucash or Gnucash/gnucash-docs repo on GitHub. You'll need to create a GitHub account if you haven't got one already and set it up for ssh access. In the example below, we'll assume a GitHub userid of "Me". Substitute your real id.
* Add that branch as a remote in your local repository and push your working branch to it:
  git remote add github ssh://git@github.com/Me/gnucash
  git branch -u github working-branch
* Perhaps an easier approach is to replace the push url:
  git remote set-url --push origin git@github.com/Me/gnucash
  git branch working-branch
* apply your ammendments and
  git push
* Now log in to your GitHub account, go to your forked gnucash repository, select <tt>working-branch</tt> from the pick list, and click ''pull request''. It's above the "last commit" line on the right in the directory view.
* In the resulting form, give your pull request a title and describe its motivation. If it's associated with a bug, use the bug number and title for your title and paste the bug URL  into the description. Note that GitHub descriptions use Markdown and that there's a preview tab to help you make sure that everything looks the way you want it.
* Click the ''Send Pull Request'' button to the right of the description block.
* If a developer requires changes to your pull request, amend your commits as necessary and force-push your branch. Don't make any changes to that working branch that aren't associated with the pull request!
* Once the pull request has been either merged or rejected, you can delete the branch:
  git branch -D working-branch
  git push github :working-branch
* If you want to continue in between with something else create another branch.

== Committers ==
Since 2014-02 all GnuCash repositories are pure git repositories:
* gnucash
* gnucash-on-windows: windows installer and build script moved here from gnucash/packaging
* gnucash-docs
* gnucash-htdocs (see [[#Conversion Notice]])

===Write Access===

FAQ: Is it possible to get write access? 

A: In principle yes, but we are quite conservative with giving out new SSH write accounts. For occasional changes people are encouraged to submit patches. We do add people as developers if they stick around, supply lots of patches, become highly involved in the project, hang out on IRC, and generally show some level of clue and prove some level of trust. But in the meantime, ''patches in Bugzilla'' and ''pull requests on github'' are the suggested route, as has been stated at other places. --[[User:Cstim|Cstim]] 08:00, 8 January 2006 (EST)

=== Set up ===
'''Note''': this set up presumes you already have commit access to the GnuCash repositories on code.gnucash.org. If you don't but believe you should, ask for this on the gnucash-devel mailing list.

==== Generate your ssh key pair ====
You'll need to generate a key-pair and provide the public half to the GnuCash repository administrator. To generate a key pair use
  ssh-keygen -t rsa -b 1024 -f gnucash-key

You can use any name you like instead of "gnucash-key".

You will also be prompted for a passphrase, with the option to leave it blank. If you provide a passphrase, you will be prompted to provide it every time you use your key. If you don't, anyone who gains access to your key can connect to whatever servers you protect with it. 

Once you have the key configured correctly and have provided it to the GnuCash repository administrator, try 
  ssh -i gnucash-key git@code.gnucash.org
You'll get the usual ssh question about the fingerprint for a new host. It should be <tt>20:23:3d:df:f3:13:34:c1:32:ca:11:77:24:21:98:01</tt>. If it is, answer "yes" to add it to your known hosts file. If you get a message followed by a list of repositories, your setup is correct and you can proceed.

Next, you'll want to to configure your local ssh client to always provide this key when connecting to code.gnucash.org. In addition, ssh should always connect as user 'git'.

On linux, you can set this up by adding the following lines in your ssh config file (~/.ssh/config):
 Host code.gnucash.org
 IdentityFile ~/.ssh/gnucash-key
 User git
: (Continue with [[#Clone the Repositories]])

===== Key generation under Windows =====

====== With MSYS ======
To set up ssh with the MSYS client, proceed exactly as above.

====== With Putty for TortoiseGit ======
For [[http://code.google.com/p/tortoisegit/ TortoiseGit]], you'll also need PuttyGen and Putty from [[http://www.chiark.greenend.org.uk/~sgtatham/putty/ PuTTY]]. 
Setting up Pageant to work with TortoiseGit is a bit involved, so we'll go through it step-by-step:

1. Use PuttyGen to convert your private key into Putty format. Launch puttygen, click the "load" button and select your private key file, then click the "save private key" button to save it in putty format.

2. Set up a Putty profile: Start Putty. 
* Set the Host URL to code.gnucash.org, port 22 on the Session page
* Open Connection:SSH:Auth and at the bottom of the panel, for "Private key file for authentication" browse for the converted keyfile you made in the previous step.
* Open Connection:Data and enter 'git' in the "Autologin username" text entry.
* Return to the Session panel, enter a name (if you use <tt>code.gnucash.org</tt> configuring TortoiseGit will be less confusing) in the text entry named "Saved Sessions" and click the "save" button.
* Click "open". If everything is done correctly, a command window will open and you'll see that message about terminal sessions not being allowed. If you are instead prompted for a password, you have messed up the username or key somehow and will need to contact the server admin to get your IP address unblocked.
: (Continue with [[#TortoiseGit on Windows]])

==== Clone the Repositories ====
Now clone the Github repository the same way as [[#Non-Committers]]. Since changes should not be pushed to the github repository, a good way to make sure that this doesn't happen by mistake is to use the same read-only URI given above for non-committers. Alternatively, fork the Gnucash repository to your Github account and clone that (use the read-write URI in that case).

Next add the repository on code.gnucash.org as a second remote, for example as 'upstream'.

  git remote add upstream git@code.gnucash.org:gnucash

Perhaps a better approach is to replace the push url:
 git remote set-url --push origin git@code.gnucash.org:gnucash 
That avoids confusion where to push and where to fetch.

That's it.
: (Continue with [[#Committing]])

===== TortoiseGit on Windows =====
* Right-click a folder in Windows™ Explorer and select TortoiseGit:Settings. At the bottom of the Network panel of the resulting dialog box, click the "Browse" button for SSH Client and navigate to <tt>C:\Program Files\TortoiseGit\bin\TortoisePlink.exe</tt>, click "open" in the file chooser, the "OK" to dismiss the Settings box.
* Right-click on a folder into which you want to check out (or already have checked out) Gnucash. If it's a fresh checkout, select TortoiseGit Checkout; otherwise select TortoiseGit:Relocate. Enter the URL as <tt>ssh://the-putty-session-name/gnucash</tt>. (Remember earlier where we said it would be less confusing if you use <tt>code.gnucash.org</tt> for the session name? That's because if you did the URL will be <tt>ssh://code.gnucash.org/repo/gnucash</tt>.)

You should now be able to commit changes via TortoiseGit.

=== Committing ===

Committing is simple:
  git add
  git commit
These two commands are used to record your changes ''locally''.

  git push upstream local-branch:remote-branch

Will push your changes ''back to the master'' repository.

=== Branching and Merging ===

The "canonical" repositories at code.gnucash.org and their mirror at github.com/Gnucash have 2 active branches:

'''master''' is the ''development branch''. All ''new features'' should be committed to this branch and this branch only. Unstable releases during the beta period leading up to a new stable release series will be tagged on this branch and the tarballs generated from the tag commits. Bugs reported against an unstable release should be checked to see if they exist on the stable release; if they do they should be reassigned to the stable release and fixed on '''maint''', then merged. '''N.B.'''If for some reason a change is committed to '''master''' that should have been done in '''maint''', '''''cherry-pick''''' that commit to '''maint'''. Merging '''master'''->'''maint''' would add all of the development changes into '''maint''', which would be bad.

'''maint''' is the ''current stable release branch''. All ''bugs reported on the released version'' should have the fixes committed to this branch and then merged to '''master'''. Stable releases will be tagged on this branch and the tarballs generated from the tag commits.

There are also ''archival branches'', one for each stable release series no longer under development. Note that before 2.6 we used Subversion or CVS for version control and the practices were different, so you'll see different commit patterns when looking at historical branches.

The gnucash repository contains an '''archive''' branch which tracks '''master''' up to the point that the last subversion feature branch (webkit, if you're curious) was merged, except that new merge commits have been added to link the feature branch merges. It shows the merge points in the right order, but the merge commit dates are all from early 2014. It is of historical interest only.

There are several ''abandoned feature branches'' which were never integrated into GnuCash. They are also present for historical interest only.

==== Bugs and New Features ====
To repeat the policy in the description of the active branches:
* '''Bug fixes''' should always be rebased onto the '''maint''' branch then merged to '''master''' unless either they don't affect '''maint''' or they are not going to be fixed on '''maint''' because the required changes are complex enough that it would risk making '''maint''' unstable.
* '''New Features''' are '''''always''''' rebased or merged onto '''master'''. New features are '''not allowed''' on '''maint'''.

When and how to use branches depends on the complexity of the changes:
* '''Small changes''', which can be completed quickly and in a single commit, do not require a feature branch.
* '''Larger changes''', which ''might''
** require ''more than one commit'' or
** take ''more than a few hours'' to write and test
: should be done on a private branch which is '''rebased''' onto the appropriate main branch before pushing the changes to the main repository. This helps keep the main branch's history linear, which in turn makes it easier to read and displays better in a graphical tool.
* '''Major changes''',
** which are completed in ''stages which are made public'' in parts or
** which for any reason are best ''visualized as standing apart from the main branch'',
: should be merged with <tt>--no-ff</tt> to prevent them from fast-forwarding the main branch.

'''Bug Fix Feature Branch Example'''
  git checkout -b my-bug-fix maint
  # make changes, commit, test, fix, etc.
  git checkout maint
  git pull --rebase
  git rebase maint my-bug-fix
  # make && make check to ensure that you're not pushing a broken build!
  git push upstream maint
  git checkout master
  git pull --rebase
  git merge maint
  # rebuild and make check again
  git push upstream master

'''Major Feature Branch Example'''
  git checkout -b my-new-feature master
  # write and test the first phase of your feature, committing often.
  git checkout master
  git pull --rebase
  git merge --no-ff my-new-feature
  # rebuild and make check for safety
  git push upstream master
  git checkout my-new-feature
  # write the next phase and repeat until done.

'''Caution:''' When ''switching the branch'' you should cleanup your build dir to avoid "strange behavior". At least you should run <tt>make distclean</tt> before, but better might be
 cd <yourbuild dir>
 rm  -rf * && ../configure <your params> && make && make check
after switching. In case you are building intree you can run
 git clean -fdx -e /.project -e /.cproject -e /.autotools -e /.settings/
instead to remove everything not in the repository with a few exceptions (-e ...). Above exceptions are files, where [[Eclipse]] stores its settings. 

===== Resolving Merge Conflicts =====

Sometimes, e.g. after a new release, the first merge in gnucash-docs will result in an conflict about the version number:
<pre>git status
# On branch master
# You have unmerged paths.
#   (fix conflicts and run "git commit")
#
# Changes to be committed:
#
:
# Unmerged paths:
#   (use "git add <file>..." to mark resolution)
#
#       both modified:      configure.ac
:</pre>

configure.ac will now contain a section

<pre><<<<<<< HEAD
AC_INIT(gnucash-docs, 2.6.99)
=======
AC_INIT(gnucash-docs, 2.6.4)
>>>>>>> maint</pre>

Just remove the markers and the wrong section with your preferred editor.

Don't forget to run <tt>git commit -a</tt> to tell git, you are ready!

=== Link Bugzilla Entries ===

Often commits are related to [[Bugzilla]] entries. In this case the commit message should contain 
* '''<tt>Bug </tt>''<bug number>''<tt>:</tt>''<bug title>''''' or
* '''<tt>Bug </tt>''<bug number>''<tt> - </tt>''<bug title>'''''.

You can specify it as the first line if the commit fully fixes the related bugzilla issue, or mention it in the body of the commit message otherwise.

Adding these references will make it easier for committers to use the ''git bz'' command while manipulating the commits.

=== Patches and Pull Requests ===
A common committer duty is handling patches and pull requests from non-committers. The procedure for both is:
* Review the code for formatting, style, good coding practice, good commit message, etc. Make comments and get the submitter to make any necessary changes.
* Download and apply the patch to the appropriate branch. If the change is complex you may want to make a local branch to work in.
* Build and test. Discuss any problems with the submitter and get the patch in good shape, ready to commit.
* If the patch is on the ''maint'' branch, do a test merge onto ''master''. Resolve any merge issues with the submitter; if necessary, get a "patch to the patch" to resolve the merge conflicts.
* Once everything is ready, merge your working branch into ''master'' or ''maint'':
** Reset your local ''maint'' and/or ''master'' branches to remove any test merges.
** Pull them to get any commits others might have pushed while you're working.
** Apply the final patches or merge your working branch. When applying take care the patches are committed with the appropriate authorship.
*** If the patches were created with ''git format-patch'' and hence applied using ''git am'' this should be ok.
*** Also if the patches are in another repository or branch and you use ''git pull'' to apply them the author should be ok as well.
*** If the patches came as ordinary diff files to be applied with ''git apply'', you should commit these changes with ''git commit --author "name <email>"'' with the proper author name and e-mail filled in.
** Merge ''maint'' into ''master'' if required; if there's a "patch to the patch" to handle conflicts between ''maint'' and ''master'', use <tt>--strategy=theirs</tt> to the merge, then apply the repair patch and commit '''amending'' the merge commit:
  git checkout master
  git merge --strategy=theirs maint
  git apply patch-to-the-patch
  git commit -a --amend
* Push the results
* Close the pull request or mark the patches "Committed" in Bugzilla.

'''Pull Request Notes:'''
* When processing a pull request it's safest to download the pull request as a (series of) patch(es). When you pull from the submitter's GitHub repository branch you risk conflicts because it hasn't been rebased to match the current state of the branch you're pulling to, though you can avoid that by making a working branch from the main branch commit that's at the base of the submitter's working branch. There may also be problems if the submitter has made changes to the working branch after making the pull request.
* Note that code review comments can be made inline from the "Files Changed" tab of the pull request page on GitHub.

----

Other options exists as well; feel free to edit this wiki page.

[[Development_Process|Back to Development Process]]

[[Category:Development]]

== Collaboration ==

With rare exceptions we don't want to clutter the master repository with feature branches, so how can two developers collaborate on one?
There are several ways to go about it: You can pass patches between you over email, chat, or carrier pigeon; Git is designed to handle that easily (except for carrier pigeon transport, as that requires retyping the patch, which is a pain [[http://en.wikipedia.org/wiki/B._F._Skinner#Pigeon-guided_missile Really?]]). You can arrange for all of your repositories to be available on the net, and <tt>git pull</tt> amongst yourselves. Or you can use one of the public repositories like Github or Gitorious to manage your changes.

= Accessing GnuCash BugZilla from Git =

There is a plugin, called git-bz, written for Git that allows it to talk to BugZilla and do things with bugs like attach patches, add comments, mark as fixed, etc.&ndash;all from the command line. See the [[git-bz]] page for details.

= Htdocs Conversion Notice =
For some time now the gnucash-htdocs repository has been used to store both the website and a compiled version of our documentation in html, pdf, ebup and mobi formats. The problem with this was that the ''compiled documentation'' is pretty large. The repository was finally over 800Mb in size and increasing with each release. That meant that over time a simple clone of the repository would cost increasingly more bandwidth, diskspace and users time.

People that wish to work on the website don't need this compiled documentation so the large download was an unnecessary burden. We have decided to fix this by splitting off the compiled documentation into a separate repository, which is only relevant for a release manager. After the split, the gnucash-htdocs repository has been regenerated without the docs history.

== Update your clones and forks ==
If you have your own clone of the gnucash-htdocs git repository you will have to reclone the new repository if you want to enjoy the smaller footprint. If you have local changes you'll want to preserve them. So instead of deleting the directory rename it. For the examples we'll call it <tt>gnucash-htdocs-old</tt>, and we'll clone into <tt>gnucash-htdocs-new</tt>. That's just to make sure we don't forget which is which. After the import process is complete, you can remove <tt>gnucash-htdocs-old</tt> and rename <tt>gnucash-htdocs-new</tt>.

You've been assiduous about always using <tt>git pull --rebase</tt>, right? No? You've got changes mixed into <tt>master</tt>? No matter. <tt>rebase</tt> to the rescue: (I'm using <tt>master</tt> as an example here, but it could be any tracking branch.)
  cd gnucash-htdocs-old
  git pull --rebase
  git branch -m master foo #This is your new feature branch. You can call it anything you like
  git branch -t master origin/master
  git rebase master foo
There. Now all of your changes are in a nice feature branch. You might have to reconcile some conflicts, but better sooner than later, eh? If you already have feature branches -- we'll use <tt>foo</tt> for our example -- just make sure that it's up to date with its tracking branch:
  git checkout master
  git pull --rebase
  git rebase master foo

Now you're ready to export your changes. Do this one feature branch at the time. Create a set of patches for your feature branch:
  cd ../gnucash-htdocs-old
  git checkout foo
  git format-patch --stdout master > ../foo.mbox

And import your branch foo into the new repo:
  cd ../gnucash-htdocs-new
  git checkout master
  git checkout -b foo
  git am ../foo.mbox

That's it. Repeat for each feature branch and tracking branch. When you're done and really, really sure that everything is properly set up, 
you can delete <tt>gnucash-htdocs-old</tt> and any <tt>foo.mbox you created</tt>.

'''Note:''' When you run <tt>git checkout master</tt> in <tt>gnucash-htdocs-new</tt>, git ''should'' respond with 
  Checking out files: 100% (1247/1247), done.
  Branch master set up to track remote branch master from origin.
  Switched to a new branch 'master'
''If it doesn't'', then it may have gotten confused. If 
  git log --oneline -n 10
doesn't produce the expected results, 
  git branch -D master
  git branch -t master origin/master
To get the proper master branch.

;Github Forks: If you have made a Github fork you will need to make sure that your local repo is current and then delete the fork and re-fork the regenerated repository, then proceed according to the instructions above, finally pushing any new branches back to your Github fork.

= Related Topics =

* [https://help.github.com/ GitHub Help] in particular [https://help.github.com/articles/fork-a-repo/ fork-a-repo].
* [[Git Migration]] tracked the required changes to our infrastructure and support code before we were able to switch to a pure git based workflow.
* [[Git vs Svn]] has some background on conceptual differences between svn and git. This may help people with a strong svn background to make the switch to git.
* Purely for historical interest: GnuCash has been maintaining its source code in a hybrid svn-git system for a while. It has now moved on to a pure git environment. We had some documentation for this hybrid setup as well. The current page's history will reveal how a user had to configure her local setup, [[Git_Svn_Mirror]] explains what was needed on the server side.
* [[Git For Newbies]] has basic suggested work flow for modifying GnuCash and more details about what each git command does for those new to git.
* [[Documentation_Update_Instructions]] focuses specifically on documentation updates.