• 2016-09-29

    Migrating a SVN repository to Git (Bitbucket)

    Migrating a SVN repository to Git (Bitbucket)

    Preface

    This article explains how to migrate a SVN repository to Git. Although this guide uses BitBucket as the Git repository, you can easily adjust the steps to migrate to a different Git repository provider.

    I was recently tasked to migrate a repository from SVN to Git (BitBucket). I have tried the the importer from BitBucket but it failed due to corruption in our SVN repository.

    So I had no other alternative than to do things by hand. Below is the process I have used and some gotchas.

    Authors

    SVN stores just a username with every commit. So nikos could be one and Nikos could be another user. Git however stores also the email of the user and to make things work perfectly we need to create an authors.txt file which contains the mapping between the SVN users and the Git users.

    NOTE The authors.txt file is not necessary for the migration. It only helps for the mapping between your current users (in your Git installation).

    The format of the file is simple:

    captain = Captain America <[email protected]>
    

    If you have the file ready, skip the steps below. Alternatively you can generate the authors.txt file by running the following command in your SVN project folder:

    svn log -q | \
        awk -F '|' '/^r/ {sub("^ ", "", $2); sub(" $", "", $2); print $2" = "$2" <"$2">"}' | \
        sort -u > authors.txt
    

    Conventions

    • The source SVN repository is called SVNSOURCE
    • The target GIT repository is called GITTARGET
    • The SVN URL is https://svn.avengers.org/svn

    Commands

    Create a work folder and cd into it

    mkdir source_repo
    cd source_repo/
    

    Initialize the Git repository and copy the authors file in it

    git svn init https://svn.avengers.org/svn/SVNSOURCE/ --stdlayout 
    cp ../authors.txt .
    

    Set up the authors mapping file in the config

    git config svn.authorsfile authors.txt
    

    Check the config just in case

    git config --local --list
    

    The output should be something like this:

    core.repositoryformatversion=0
    core.filemode=true
    core.bare=false
    core.logallrefupdates=true
    svn-remote.svn.url=https://svn.avengers.org/svn/SVNSOURCE
    svn-remote.svn.fetch=trunk:refs/remotes/trunk
    svn-remote.svn.branches=branches/*:refs/remotes/*
    svn-remote.svn.tags=tags/*:refs/remotes/tags/*
    svn.authorsfile=authors.txt
    

    Get the data from SVN (rerun the command if there is a timeout or proxy error)

    git svn fetch
    

    Check the status of the repository and the branches

    git status
    git branch -a
    

    Create the new bare work folder

    cd ..
    mkdir source_bare
    cd source_bare/
    

    Initialize the bare folder and map the trunk

    git init --bare .
    git symbolic-ref HEAD refs/heads/trunk
    

    Return to the work folder

    cd ..
    cd source_repo/
    

    Add the bare repo as the remote and push the data to it

    git remote add bare ../source_bare/
    git config remote.bare.push 'refs/remotes/*:refs/heads/*'
    git push bare
    

    Return to the bare work folder and check the branches

    cd ..
    cd source_bare/
    git branch
    

    Rename trunk to master

    git branch -m trunk master
    

    Note all the branches that are prefixed /tags/ and modify the lines below (as many times as necessary) to convert SVN tags to Git tags

    git tag 3.0.0 refs/heads/tags/3.0.0
    ...
    git branch -D tags/3.0.0
    ...
    

    Alternatively you can put the following in a script and run it:

    git for-each-ref --format='%(refname)' refs/heads/tags | \
    cut -d / -f 4 | \
    while read ref
    do
      git tag "$ref" "refs/heads/tags/$ref";
      git branch -D "tags/$ref";
    done
    

    Check the branches and the new tags

    git br
    git tags
    

    Check the authors

    git log
    

    Push the repository to BitBucket

    git push --mirror [email protected]:avengers/GITTARGET
    

    Enjoy