3.11.3. Migrating from CVS

The procedure to migrate to Git is as follows. The idea is to switch version control systems without changing the version of Bugzilla you are using, to minimise the risk of conflict or problems. Any upgrade can then happen as a separate step.

3.11.3.1. Download Code from Git

First, you need to find what version of Bugzilla you are using. It should be in the top right corner of the front page but, if not, open the file Bugzilla/Constants.pm in your Bugzilla directory and search for BUGZILLA_VERSION.

Then, you need to download an additional copy of your current version of Bugzilla from the git repository, and place it in a separate directory alongside your existing Bugzilla installation (which we will assume is in a directory called bugzilla).

To do this, you will need a copy of the git program. All Linux distributions have it; search your package manager for "git". On Windows or Mac OS X, you can download the official build.

Once git is installed, run these commands to pull a copy of Bugzilla:

git clone https://github.com/bugzilla/bugzilla bugzilla-new

cd bugzilla-new

git checkout release-$VERSION

Replace $VERSION with the three-digit version number of your current Bugzilla, e.g. "4.2.2". (If the the final digit would have been a 0, omit it - so use "4.4" for the first release in the 4.4 series.)

You will get a message about a 'detached HEAD'. Don't worry; your head is still firmly attached to your shoulders.

3.11.3.2. Save Any Local Customizations

Go into your original Bugzilla directory and run this command:

cvs diff -puN > patch.diff

If you have made customizations to your Bugzilla, and you made them by changing the Bugzilla code itself (rather than using the Extension system), then patch.diff will have significant content. You will want to keep a copy of those changes by keeping a copy of this file and any files referenced in it by "Only in" lines. If the file has zero size or only insignificant content, you haven't made any local customizations of this sort.

3.11.3.3. Shut Down Bugzilla

At this point, you should shut down Bugzilla to make sure nothing changes while you make the switch. Go into the administrative interface and put an appropriate message into the shutdownhtml parameter, which is in the "General" section of the administration parameters. As the name implies, HTML is allowed.

This would be a good time to make Backups. We shouldn't be affecting the database, but you can't be too careful.

3.11.3.4. Copy Across Data and Modules

Copy the contents of the following directories from your current installation of Bugzilla into the corresponding directory in bugzilla-new/:

lib/
data/
template/en/custom (may or may not exist)

You also need to copy any extensions you have written or installed, which are in the extensions/ directory. The command cvs status extensions/ should help you work out what you added, if anything.

Lastly, copy the following file from your current installation of Bugzilla into the corresponding place in bugzilla-new/:

localconfig

This file contains your database password and access details. Because your two versions of Bugzilla are the same, this should all work fine.

3.11.3.5. Reapply Local Customizations

If your patch.diff file was zero sized, you can jump to the next step. Otherwise, you have to apply the patch to your new installation. If you are on Windows and you don’t have the patch program, you can download it from GNUWin. Once downloaded, you must copy patch.exe into the Windows directory.

Copy patch.diff into the bugzilla-new directory and then do:

patch -p0 --dry-run < patch.diff

The patch should apply cleanly because you have exactly the same version of Bugzilla in both directories. If it does, remove the --dry-run and rerun the command to apply it for real. If it does not apply cleanly, it is likely that you have managed to get a Bugzilla version mismatch between the two directories.

3.11.3.6. Swap The New Version In

Now we swap the directories over, and run checksetup.pl to confirm that all is well. From the directory containing the bugzilla and bugzilla-new directories, run:

mv bugzilla bugzilla-old

mv bugzilla-new bugzilla

cd bugzilla

./checksetup.pl

Running checksetup.pl should not result in any changes to your database at the end of the run. If it does, then it's most likely that the two versions of Bugzilla you have are not, in fact, the same.

3.11.3.7. Re-enable Bugzilla

Go into the administrative interface and clear the contents of the shutdownhtml parameter.

3.11.3.8. Test Bugzilla

Use your Bugzilla for several days to check that the switch has had no detrimental effects. Then, if necessary, follow the instructions in Upgrading with Git to upgrade to the latest version of Bugzilla.

3.11.3.9. Rolling Back

If something goes wrong at any stage of the switching process (e.g. your patch doesn't apply, or checksetup doesn't complete), you can always just switch the directories back (if you've got that far) and re-enable Bugzilla (if you disabled it) and then seek help. Even if you have re-enabled Bugzilla, and find a problem a little while down the road, you are still using the same version so there would be few side effects to switching the directories back a day or three later.