Ubuntu X-SWAT uses git now
We are now using git for the packages with biggest set of changes. This page is a simplified version of the Debian git-usage page specifically for our needs.
There is also a web interface to review changes: http://git.debian.org/.
Direct links to current Ubuntu branches:
Git archive policy
Currently we only branch a few packages, since those have the most changes and have traditionally been painful to merge. The rest are better to just remain sync'able or merged when there are small changes. Changes that benefit Debian are being pushed back so that the delta is kept as small as possible.
Basic tutorial
First you need to pull the repository on your disk, and change the working branch. This is also the procedure to create the initial ubuntu branch. For instance to pull xorg you would do:
git clone ssh://user-guest@git.debian.org/git/pkg-xorg/debian/xorg.git git checkout -b ubuntu origin/ubuntu HEAD is now at cdbd698... Prepare changelog for upload. Switched to branch "ubuntu"
But if you've already done that in the past, you need to update your local branch to match remote (TODO: what if there are local changes?)
# make sure you are on the correct local branch git checkout ubuntu # pull from git.debian.org git pull
Check the success by running these
git status # On branch ubuntu nothing to commit (working directory clean) git log
The first thing usually is to merge with a new Debian release. The simplest way to do it is to use git-merge(1) (note that Debian release tags use a hyphen, where upstream tags use underscores)
git merge <tag>
It most likely complains that there are conflicts, so then make sure you have a merge tool of your choice installed (meld is one alternative) and then run git-mergetool
git mergetool
Merging the files: debian/changelog debian/control
Normal merge conflict for 'debian/changelog':
{local}: modified
{remote}: modified
Hit return to start merge resolution tool (meld): Merge leaves behind some temporary files if there are conflicts, so clean them.
git clean Removing debian/changelog.orig Removing debian/control.orig
Now you can do other changes if necessary. Remember to git-add new files.
<edit> git add path/to/a-new-file dch git diff
and commit them.
git commit -a
When everything is set, push the changes to the repository.
git push origin ubuntu
Now it's safe to do a release. Don't forget to add -i/I as necessary, and put the tarball in the parent directory before running debuild.
debuild -I".git" -S -sa -v$previousUbuntuVersion ### for xorg debuild -i".git" -S -sa -v$previousUbuntuVersion ### for rest with an orig.tar.gz
After reviewing the resulting package (debdiff et al) it is ready for upload!
Recovering from mistakes
There are (at least) two ways to revert a change, either reverting and older commit with
git revert <hash>
or by resetting the HEAD if you want to just revert the latest (set of) change(s)
git reset --hard <hash of the new HEAD>
or alternately use this to go back revisions, replacing 1 with how many you wish to go back.
git reset --hard HEAD~1
Reverting leaves a message on the log, so it's not a "clean" way to undo changes, but necessary when the changes are already committed to the repository, or when there are changes made after that commit.
Sometimes you need to clean up the mess you've done and start from a clean table. In that case you'd better just first clean all local changes
git clean -xdf
And then reset to the head of the remote ubuntu branch
git reset --hard origin/ubuntu
Merging a new upstream release
When merging new upstream releases, it's common to have conflicts due to differences between the branches etc. Sometimes git can't handle the merge gracefully, so you need to do:
# optionally cleanup your local repo git clean -df # checkout the upstream branch you want git checkout -b new-branch upstream/master # tell git that we've merged the changes of the old branch and ignore any changes # that are there git merge -s ours mesa_7_2 # now pull in the packaging branch git merge debian-experimental # ..and handle the conflicts (if any) sudo apt-get install meld git mergetool # Check your work git status # Then commit the merge git commit -a
Starting a new git tree
If you have a new project to put into git, first initialize a fresh new repository:
mkdir xorg-my-tree cd xorg-my-tree git init
Add files as usual:
echo "$DEBFULLNAME <$DEBEMAIL>" > AUTHORS git add AUTHORS git commit -m "Initial creation of tree"
Tag the start of your project if you wish:
echo "[user]
signingkey = $DEBEMAIL
" >> .git/config
git tag -s INITIALThen to publish it, first initialize the external git repo on alioth:
ssh user-guest@alioth.debian.org mkdir -p ~/public_html/git/xorg-my-tree.git cd ~/public_html/git/ GIT_DIR=xorg-my-tree.git git-init chmod +x xorg-my-tree.git/hooks/post-update
And then from your local machine, push your initial release up:
git push user-guest@alioth.debian.org:public_html/git/xorg-my-tree.git master git repack
Creating a new branch for an older Ubuntu release
Say you have a patch to mesa for a previous Ubuntu release.
First, check out the current git tree for Ubuntu development as above. Then check out the last commit for the Ubuntu release you wish to patch.
git checkout <LAST-REF> -b ubuntu-oneiric
Now, add your patch, changelog entry, and so on, and push the branch back to debian git:
git commit -a -m "Cherrypick of upstream patch" git push ssh://user-guest@git.debian.org/git/pkg-xorg/lib/mesa.git ubuntu-oneiric
Useful commands
Check the tree for spurious files (could be left after a merge from upstream etc)
git clean -dnx
Cherrypick a fix from Debian's upstream snapshot and add it as a patch:
git pull git checkout origin/upstream-experimental -b upstream-experimental git log # Locate the desired commit <REF> git checkout ubuntu git cherry-pick REF git show REF > ./debian/patches/100_foo_bar.patch git reset --hard HEAD^ git add debian/patches/100_foo_bar.patch dch -i -m "Cherrypick REF from upstream as 100_foo_bar.patch" git commit -a -m "Cherrypick REF from upstream as 100_foo_bar.patch"