wiki:DeveloperGuidelines/Git

Version 66 (modified by Pat Tressel, 8 years ago) ( diff )

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Git

Sahana Eden uses the Git DVCS & hosts active branches on GitHub

Developer Workflow

Fork a fresh repository

If you've not used GitHub before:

  1. Sign-up for an account on GitHub
  2. Set up git on you your computer by following these instructions.
    Note: In order to contribute code back to the Eden project, you need to "push" your changes to GitHub, and GitHub requires you to authenticate for that. The instructions describe authenticating using a password. If you don't want to do do that, you can use SSH keys instead, but the SSH setup is longer, and they do not provide instructions for Windows. If you're using Windows, you can follow these instructions. They're for Launchpad, not GitHub. The only difference is, while you're doing Step 5 (which has you copy the "OpenSSH" formatted public key to the clipboard), go over to the GitHub instructions, to the "Add your SSH key to GitHub" section. Ignore the Linux commands and do the part that saves your public key in your GitHub account. If you want, you can also save that public key in a file.
  3. There is on-line help at GitHub

Then get your own copy of the Eden repository (repo) on both GitHub and your local machine:

  1. Fork the Eden repo at: https://github.com/flavour/eden/fork_select
  2. Use git to clone your own new fork down to your PC, as follows:
    cd web2py/applications
    git clone git@github.com:mygitusername/eden.git
    cd eden
    git remote add upstream git://github.com/flavour/eden.git
    

https://docs.google.com/drawings/pub
https://docs.google.com/drawings/d/1TppJKr9Qrq6I2KpkljRixx5gYh1seRqCXk8KDWdeIF0/edit

Ongoing Coding

cd web2py/applications/eden

# Update your working directory with latest code from Trunk
git pull upstream

# Write Code

# Quick review of code (no test code left in, etc)
git diff

# Check for any new files which need adding
git status
git add .

# Commit Code (Note, no pushes to GitHub here)
git commit -am "My Story: Part 1"
.
.
.
git commit -am "My Story: Part N"

# Merge latest Trunk
git pull upstream

# Resolve any conflicts (see below for how)

# Commit fixed code
git add .
git commit -a

# Squash commits to as few as possible to keep revision history clean & make it easier to review the work
# http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html
git rebase -i

# Push to your branch on GitHub
git push

https://docs.google.com/drawings/pub
https://docs.google.com/drawings/d/1KElPNMq_annNSi_2f5r9grD-c0c_aZh1KBAOqSAtuPA/edit

Once you have pushed to your branch on GitHub, you will likely want this to be merged with Trunk - this should be done via a Pull Request. This is done on GitHub:

https://docs.google.com/drawings/pub
https://docs.google.com/drawings/d/1QmGeuQvFpg3pDQpM9xu81V7MlVy4uU8EzVIRqQ14MwU/edit

Resolving Merge Conflicts

If you encounter conflicts during the rebase, the conflicts will be tagged in the files with:

<<<<<<< HEAD
# Commits from Trunk
=======
# Commits from <mystory>
>>>>>>> "My Story"

You can correct these conflict in your code text editor, then add them andcontinue the rebase:

git add -u
git rebase --continue

You can create the .THIS & .OTHER files using:

git show :2:file.txt > file.txt.THIS
git show :3:file.txt > file.txt.OTHER

You can use the changes to a file in the remote branch (theirs / OTHER):

git checkout --theirs filename.c
git add filename.c
git commit 

...or the changes to a file in your local branch (ours / THIS):

git checkout --ours filename.c
git add filename.c
git commit

...or the changes to ALL files in the remote branch (theirs / OTHER):

git checkout --theirs . # checkout our local version of all files
git add -u             # mark all conflicted files as merged
git commit             # commit the merge

Or the changes to ALL files in your local branch (ours / THIS)

git checkout --ours . # checkout our local version of all files
git add -u            # mark all conflicted files as merged
git commit            # commit the merge

Although on Windows this seems by default to produce UTF-16 files! ('UCS-2 Little Endian'). A script to make this process easier for Windows users is attached: merge.cmd

Reverting to last committed code

If you want to throw away all uncommitted changes (i.e. 'bzr revert'), then:

git reset --hard HEAD

Rebasing after pushing to GitHub

Squash your commits if they are not in between two executions of git pull or git merge:

# Stash your current work
git stash
# N = number of commits to squash
git reset HEAD@{N}
git commit -am 'Your commit message for the one-big-commit'
# Push to your branch on GitHub, overwriting any previous code there
git push origin +master
# Restore your work in-progress
git stash pop

Undoing a commit

You may need to remove a commit you've made, either if you find you don't want it, or if it needs to be fixed. (Note if your commit has already been pushed to GitHub and accepted into the trunk, then you should use a new commit to take out unwanted changes. This section only applies if you're fixing up your repository before the changes are in trunk.)

If you want to fix up your latest commit, you can undo the commit, and unstage the files in it, by doing:

git reset HEAD~1

This will return your repository to its state before the git add commands that staged the files. Your changes will be in your working directory. HEAD~1 refers to the commit below the current tip of the branch.

If you want to uncommit N commits, but keep the code changes in your working directory:

git reset HEAD~N

If you want to get rid of your latest commit, and do not want to keep the code changes, you can do a "hard" reset.

git reset --hard HEAD~1

Likewise, if you want to discard the last N commits, and do not want to keep the code changes:

git reset --hard HEAD~N

If you are not entirely sure you want to discard the code changes, but need a branch without them, you can simply check out a new branch that ends at the last commit you want. E.g. to make a branch that ends N commits before the latest:

git checkout -b <new_branch_name> HEAD~N

See below for more on using multiple branches. To remove a commit from your repository on GitHub, use either the hard reset or new branch method above to reset your local repository to the commit you want on GitHub. GitHub will not let you overwrite a branch with a different history unless you tell it to with the --force option. If your local and remote branches have the same names, you only need to specify the branch name once, without the ":".

git push --force origin <local_branch_name>:<github_branch_name>

Creating a second branch

You may want multiple branches in your repository, e.g. for working on separate tasks, or for experimentation, or as a backup before doing a rebase.

Creating a second working directory and repository

If you wish to have multiple directories containing different branches, you can run these as separate web2py applications. (Note this is not a standard manner of working when using git, and is generally only needed if you are working on multiple projects at the same time, and need to preserve their databases and other state.)

  • Create a fresh clone:
    cd web2py/applications
    git clone git@github.com:flavour/eden.git <new_repository>
    
  • Setup a new repository on GitHub -- see: https://github.com/repositories/new
  • Add remotes.
    git remote add upstream git@github.com:flavour/eden.git
    git remote add origin git@github.com:<my_git_username>/<new_repository>.git
    
  • Push to GitHub:
    cd <new_repository>
    git push -u origin master
    

Using Patches

If you have made changes to one branch & wish to backport them to another branch, then this is done most easily using a Patch:

Story Branches

The Story Branch pattern allows pushing interim work to GitHub for review & also allowing contributing quick fixes to Trunk without needing to complete the interim work:

git checkout -b <mystory>

git commit -a
...
git commit -a

# Quick review of code (no test code left in, etc)
git diff master...HEAD

https://docs.google.com/drawings/d/1Vhvm1EmqWOVNZkZsiJ0MLLpdTl6H_ya263Tdb2HK1N0/edit

Developer Configuration

git config --global user.name "Your Name"
git config --global user.email your@email.com
git config --global github.user yourgithubusername
git config --global github.token yourtoken
git config --global core.editor "'C:/Program Files (x86)/Notepad++/notepad++.exe' -multiInst -notabbar -nosession -noPlugin"
git config --global merge.tool diffmerge
git config --global diff.tool diffmerge
git config --global difftool.diffmerge.cmd 'C:/Program Files (x86)/Git/etc/wrappers/git-diff-diffmerge-wrapper.sh' "$LOCAL" "$REMOTE"
git config --global difftool.prompt false
git config --global merge.tool diffmerge
git config --global mergetool.diffmerge.cmd 'C:/Program Files (x86)/Git/etc/wrappers/git-merge-diffmerge-wrapper.sh' "$PWD/$LOCAL" "$PWD/$BASE" "$PWD/$REMOTE" "$PWD/$MERGED"
git config --global mergetool.prompt false
git config --global mergetool.trustExitCode false
git config --global mergetool.keepBackup false

An alternative to diffmerge is Perforce's free P4V:

Windows

Install Console & Diffmerge & configure Powershell.

Developer Tools

.gitattributes runs version.py to update the VERSION file on commit

Possibly we could add a pre-commit hook to run tests, e.g. based on http://tech.yipit.com/2011/11/16/183772396/ or http://blog.penzilla.net/2011/09/git-pre-commit-hook-for-python-now-with.html

Notifications

You can subscribe to commits via RSS, e.g. to subscribe to Trunk, use:

If you wish to receive email notification of commits, then you can use an Email to RSS service like:

Resources

History

Why?

Sahana Eden has decided to move from Bzr/LaunchPad to Git/GitHub

  • The current repository is huge & bloated, taking too long to download.
  • Even simple changes take an age to Pull down to servers
  • Web2py no longer supports Bzr/LaunchPad, so we want to be able to maintain a common tool to work with both repositories.
  • New developers are likely to be more familiar with Git/GitHub

How?

The preferred approach is to have a clean repository, in order to get the maximum benefit from the migration...although it is technically possible to migrate the commit history. Commit History will instead be maintained on the LaunchPad site as an archive

Migrating existing Branches

Merge branch with trunk using normal Bzr tools

Assuming that you have already forked Eden Trunk, then you will need to create a new repository manually for additional branches, as you cannot fork your own project on GitHub:

  • https://github.com/repositories/new
    cd web2py/applications
    git clone git@github.com:flavour/eden.git <mybranch>2
    
  • Move .git & .gitignore from <mybranch>2 to <mybranch>
  • Delete the rest of <mybranch>2
  • Edit .git/config:
    [remote "origin"]
        fetch = +refs/heads/*:refs/remotes/origin/*
        url = git@github.com:<mygitusername>/<mybranch>.git
    
  • Create the initial repo for this new branch
    cd <mybranch>
    git add .
    git commit -am "Initial Git version of My branch"
    git push -u origin master
    git remote add upstream git://github.com/flavour/eden.git
    

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