1. Migrating to Git

The section is based on: https://git-scm.com/book/en/v2/Git-and-Other-Systems-Migrating-to-Git

1.1. Prepare author information

However, the import isn’t perfect, and because it will take so long, you may as well do it right. The first problem is the author information. In Subversion, each person committing has a user on the system who is recorded in the commit information. If you want to map this to better Git author data, you need a mapping from the Subversion users to the Git authors. Create a file called users.txt that has this mapping in a format like this:

schacon = Scott Chacon <schacon@geemail.com>
selse = Someo Nelse <selse@geemail.com>

To get a list of the author names that SVN uses, you can run this:

$ svn log --xml --quiet | grep author | sort -u | perl -pe 's/.*>(.*?)<.*/$1 = /' > users.txt

That generates the log output in XML format, then keeps only the lines with author information, discards duplicates, strips out the XML tags. (Obviously this only works on a machine with grep, sort, and perl installed.) Then, redirect that output into your users.txt file so you can add the equivalent Git user data next to each entry.

1.2. Create git branches and tags

You can provide this file to git svn to help it map the author data more accurately. You can also tell git svn not to include the metadata that Subversion normally imports, by passing --no-metadata to the clone or init command (though if you want to keep the synchronisation-metadata, feel free to omit this parameter). This makes your import command look like this:

$ git svn clone https://gforge-next.eufus.eu/svn/<SVN_PROJECT_NAME>/ \
      --authors-file=users.txt --no-metadata --prefix "" -s my_project
$ cd my_project

git svn clone --trunk=/trunk --branches=/branches --branches=/bugfixes --tags=/tags --authors-file=users.txt --no-metadata --prefix ""  https://<USERNAME>@gforge-next.eufus.eu/svn/<SVN_PROJECT_NAME> my_project

In case you consider the current layout of your SVN/Git repository more elaborate than usual (convoluted /tags, /trunk and /branches or heavily reliant on externals), please contact the ACH team to get some assistance on the migration.

You should also do a bit of post-import cleanup. For one thing, you should clean up the weird references that git svn set up. First you’ll move the tags so they’re actual tags rather than strange remote branches, and then you’ll move the rest of the branches so they’re local.

$ bash

To move the tags to be proper Git tags, run:

$ for t in $(git for-each-ref --format='%(refname:short)' refs/remotes/tags); do git tag ${t/tags\//} $t && git branch -D -r $t; done

This takes the references that were remote branches that started with refs/remotes/tags/ and makes them real (lightweight) tags.
Next, move the rest of the references under refs/remotes to be local branches:

$ for b in $(git for-each-ref --format='%(refname:short)' refs/remotes); do git branch $b refs/remotes/$b && git branch -D -r $b; done

It may happen that you’ll see some extra branches which are suffixed by @xxx (where xxx is a number), while in Subversion you only see one branch. This is actually a Subversion feature called “peg-revisions”, which is something that Git simply has no syntactical counterpart for. Hence, git svn simply adds the svn version number to the branch name just in the same way as you would have written it in svn to address the peg-revision of that branch. If you do not care anymore about the peg-revisions, simply remove them:

$ for p in $(git for-each-ref --format='%(refname:short)' | grep @); do git branch -D $p; done

Now all the old branches are real Git branches and all the old tags are real Git tags.
There’s one last thing to clean up. Unfortunately, git svn creates an extra branch named trunk, which maps to Subversion’s default branch, but the trunk ref points to the same place as master. Since master is more idiomatically Git, here’s how to remove the extra branch:

$ git branch -d trunk

You can easily browse the new repository using gitk command:

$ gitk --all

1.3. Prepare new project

1. Log in to https://gitlab.eufus.psnc.eu/dashboard/projects
2. Press button "New project"
3. Choose "Create blank project"
4. Fill in the project form
5. Disable option Initialize repository with a README
6. Press button "Create project"

1.4. Send changes to new Git repository

The last thing to do is add your new Git server as a remote and push to it. Here is an example of adding your server as a remote:

$ git remote add origin https://gitlab.eufus.psnc.pl/<YOUR_GITLAB_USERNAME>/<GIT_PROJECT_NAME>

Because you want all your branches and tags to go up, you can now run this:

$ git push origin --all
$ git push origin --tags

All your branches and tags should be on your new Git server in a nice, clean import.

$ git config --global credential.helper store