Cyotek Svn2Git Migration Utility

This repository hosts a naive utility for creating a Git repository from an existing SVN tree, making it useful for breaking a mono SVN Repository into smaller Git repositories.

This tool is a work in progress that I did for breaking up my own repository. It may not work for all cases, for example if root folders were renamed or moved.

It has only received limited testing and is provided AS-IS.

How does it work?

In the simplest fashion possible - you give it a location in SVN, it will enumerate the revisions in that location (and its sub folders) and will check each one out in reverse order and commit them into a Git repository with the appropriate date, author and log information. That is it, nothing fancy.

You are able to specify glob patterns for file includes and excludes, which can be useful if you want to exclude files originally accidentally committed, or that you simply don't want in the new repository.

The code is a little messy, I did start to break it up into more reusable and testable components but this work is ongoing.

Selecting Revisions

• Enter the URL of the remote SVN path you want to migrate. This will then list all revisions associated with that location.
• Optionally, enter the base path for matching files in the commit, or leave blank to use the auto detected value.
• Select the revisions you wish to migrate. Revisions that are greyed out have no files matching the base path expression.

Context-click the list view for Select All, Select None and Invert options.

More on the Base Path

The migration utility can't tell what files are "affected", and so makes a best guess based on the auto detected base path. This may not always be appropriate. For example, the below screenshot shows some of the files from a very early commit to /cyotek/trunk/cyotek/source/Libraries/Cyotek.Web.Crawler, but not that the path starts with /trunk/checkout not /trunk/cyotek and so these files are ignored.

To view the files in a revision, context-click a revision and choose File List... from the menu.

Consider a new commit where the paths do match.

The migration utility allows the base path to be specified, and to handle scenarios such as the above it allows glob expressions to be used. For example, all files from the two lists above could be captured with either of the following patterns.

• /**/Libraries/Cyotek.Web.Crawler/**/*
• /trunk/checkout/source/Libraries/Cyotek.Web.Crawler/|/trunk/cyotek/source/Libraries/Cyotek.Web.Crawler/

In the case of the latter pattern, the migration utility will automatically add **/* to patterns that don't include any glob characters.

The revisions list "greys out" any revisions where no files were matched, providing a visual clue that something is amiss.

Mapping Authors

SVN uses a simple name for attribution, but Git requires a name and email address pair. The Author Mapping tab will list any detected authors for the selected revisions, for each author ensure there is a name and email address in the pattern svn_name = git_name <git_email>.

Inclusions and Exclusions

If there are files you want to exclude from the new repository (for example a scratch program full of credentials that should never have been committed to begin with!), you can configure a set of include or exclude patterns to manage which files will be copied from each SVN checkout to the Git repository.

Enter glob patterns in either the inclusion or exclusion fields, or both. Files will only be included if they are both included and not excluded. If the includes field is blank, then all files are included. If the excludes field is blank, then no files will be excluded.

For example, if you had a folder named /src/Scratch in your repository which you didn't want migrated, then you could enter the glob /**/Scratch/**/* to the exclusion list.

Don't use backslashes in globs, the migration tool will automatically handle conversion from Windows paths.

Selecting the Git Repository

Enter the local folder where the Git repository will be located.

If you are creating a new repository, ensure the folder is empty the Use existing repository option is unchecked.

If you want to append the commits to an existing repository, ensure the folder points to the existing repository and check the Use existing repository option. This can be useful if you are having to build a Git repository from multiple sources, e.g. if a root folder was renamed or moved.

You can also customise the template used to generate commit messages. Templates are in Scriban format, with the following variables available:

• log - the SVN log message
• author - the SVN author
• revision - the revision ID
• timestamp - the commit timestamp
• repository_uri - the URI of the SVN commit

Preview

Click the Preview button to display a simplified preview. This will scan the revisions and test changed files against inclusion and exclusion patterns, then print a list of all matched files. This can be very useful to make sure you have your patterns set right, and also to review file lists in case you see something that needs adding to the exclusions.

Migrate

Click the Migrate button to start the process. For each selected revision, this tool will check that out, sync the contents with the Git repository (honoring include/exclude rules), then perform a commit.

This may take some time to perform.

Profiles

To save the current migration settings (with the exception of revision selections) to a JSON file, open the File menu and choose Save Profile As.

To load previously saved settings, open the File menu and choose Open Profile.