Git-to-qisrc cookbook

Some companies put all their code in one big VCS repository (a lot of them use Perforce; Facebook and Google use Mercurial). With Git, this is impractical.

qisrc implements a “meta-” version control system, that allows one to manage a collection of Git clones in a big “worktree”. It offers features similar to the “one-big-repository” approach, and if you squint really hard, you can think of the qisrc worktree as a VCS repo.

That means it must be possible to translate Git commands (that you would use if a project is managed using Git without qisrc) to the equivalent qisrc commands.

For the sake of this comparison, let’s suppose that the equivalent of a Git repository is a qisrc group. This makes sense if we suppose that the point of a qisrc group is to work on a project, that for some practical reason can not be kept in only one Git repository.

Let’s also suppose that the manifest is stored in the worktree. In the case of Aldebaran, this means that the worktree must have been created with “-g tools”. If the manifest is not stored in the worktree, you can also have it alongside your worktree by cloning it with Git.

Download a project

Git

git clone "git://foo/bar"

qisrc

qisrc init git@gitlab.aldebaran.lan:qi/manifest.git -g tools -g foo_bar

Create a project

Git

Let’s say that we created a repo accessible from the network at ssh://git@gitlab.aldebaran.lan/nrubinstein/foobar.git.

mkdir foo/bar
cd foo/bar
git init
git commit --allow-empty -m 'first commit'
git remote add origin git@gitlab.aldebaran.lan:nrubinstein/foobar.git
git push -u origin master

qisrc

Here, let’s create a Git repository and then create a qisrc group containing only this Git repository. This supposes that you already have a qisrc worktree.

Step 1: create the actual Git repository

Create a Git repository that is accessible from the network, like in the ‘Git’ instructions above. Do note that you need to create it locally in your qisrc worktree and to upload a “master” branch. If you do not do this before adding the Git repository to your worktree, qisrc will break.

Step 2: add the Git repository to the manifest

cd ../../manifest/default

Edit manifest.xml.

There is a line that says <remote name="origin" url="ssh://git@gitlab.aldebaran.lan"/>. This means that we will not have to repeat this part of the repo URL.

Create a line that says <repo project="nrubinstein/foobar.git" src="foo/bar" remotes="origin"/> This tag must be a child of the top-level <manifest> tag

git commit -am "Add repository foobar"

Step 3: create a group in the manifest

Edit manifest.xml to add your group:

<manifest>
  ...
  <groups>
    ...
    <group name="foobar">
      <project name="nrubinstein/foobar.git" />
    </group>

Notice that the group definition uses the (shortened) URL to the Git repository as seen in the “project” attribute of the “repo” tag, not its path in the worktree as seen in the “src” attribute of the “repo” tag.

git commit -am "Create group foobar"

Step 4: push the group

qisrc push

At Aldebaran, we are using code review for the manifest. That means that the group is not usable yet. If the push above does not go to code review, you can skip steps 5 and 6.

Step 5: create a branch

git branch foobar
git push -u origin foobar

Step 6: checkout the branch

qisrc sync
qisrc checkout foobar

Step 7: add the group

qisrc sync
qisrc add-group foobar

Create a branch

Git

git checkout -b foo_bar

qisrc

When creating the branch

Step 1: create the branch in the Git repo that you want to change

cd foo/bar
git checkout -b foo_bar

Step 2: create the branch in the manifest

cd ../../manifest/default
git checkout -b foo_bar

Then edit manifest.xml: find the line that says <repo ... src="manifest/default" /> and edit it to say branch="foo_bar". This is not strictly necessary but will make it easier to edit the branch you are working on.

Step 3: edit the manifest to switch your repo to your branch

Edit manifest.xml: find the line that says <repo ... src="foo/bar" /> and edit it to say branch="foo_bar".

git commit -am "Create branch foo_bar"
git push -u origin foo_bar

Step 4: checkout your branch for the whole worktree

cd ../..
qisrc sync
qisrc checkout foo_bar

If everything went well, this last command should do nothing.

Afterwards

Then, every time you want to change something in a Git repository that you have not changed yet, you have to reproduce step 1 and 3.

Switch to a branch

Git

git checkout foo_bar

qisrc

qisrc checkout foo_bar

When some changes are integrated

Git

When using Git, sometimes you create changes on your foobar branch and at some point they are integrated in the master branch. Typically, when that happens, you would remove the foobar branch with:

git checkout foobar
git rebase master
git checkout master
git branch -d foobar

And then you can remove the remote branch with:

git push origin :foobar

qisrc

Additionally, when using qisrc, there are two scenarios.

When some changes on some Git repo have been merged to master

Step 1: Delete the branch in the Git repo

First, do the Git steps above as you would normally do, but do not remove the remote branch yet! That would break “qisrc sync” for everyone following your branch.

Step 2: Edit the manifest

cd ../../manifest/default

Edit manifest.xml: find the line that says <repo ... src="foo/bar" branch="foobar" /> and delete the branch="foobar" part.

git commit -am "branch foo/bar of foobar has been merged back to master"
git push

Step 3: remove the remote branch

Now that the manifest is updated, removing the remote Git branch is safe.

qisrc sync
cd ../../foo/bar
git push origin :foobar

Step 4: Checkout your branch for the whole worktree

cd ..
qisrc sync
qisrc checkout foobar

If everything went well, those two commands should not change anything.

When all changes in all Git repos have been merged to master

The qisrc manifest branch is useless now, so you can remove it.

qisrc checkout master
cd manifest/default
git push origin :foobar