SINCE 0.6.0
A Gitblit federation is basically an automated backup solution from one Gitblit instance to another. If you are/were a Subversion user you might think of this as svn-sync, but better.
If your Gitblit instance allows federation and it is properly registered with another Gitblit instance, each of the non-excluded repositories of your Gitblit instance can be mirrored, in their entirety, to the pulling Gitblit instance. You may optionally allow pulling of user accounts and server settings.
The uuid is used to generate permission tokens that can be shared with other Gitblit instances.
The uuid value never needs to be shared, although if you give another Gitblit instance the ALL federation token then your uuid will be transferred/backed-up along with all other server settings.
This value can be anything you want: an integer, a sentence, an haiku, etc. You should probably keep the uuid simple and use standard Latin characters to prevent Java properties file encoding errors. The tokens generated from this value are affected by case, so consider this value CASE-SENSITIVE.
The federation feature is completely disabled if your uuid value is empty.
NOTE:
Changing your federation.uuid will break any registrations you have established with other Gitblit instances.
If you want your repositories (and optionally users accounts and settings) to be pulled by another Gitblit instance, you need to register your source Gitblit instance with a pulling Gitblit instance by providing the url of your Gitblit instance and a federation token.
Gitblit generates the following federation tokens:
%BEGINCODE%
String allToken = SHA1(uuid + "-ALL");
String usersAndRepositoriesToken = SHA1(uuid + "-USERS_AND_REPOSITORIES");
String repositoriesToken = SHA1(uuid + "-REPOSITORIES");
%ENDCODE%
The ALL token allows another Gitblit instance to pull all your repositories, user accounts, and server settings.
The USERS_AND_REPOSITORIES token allows another Gitblit instance to pull all your repositories and user accounts.
The REPOSITORIES token only allows pulling of the repositories.
Individual Gitblit repository configurations such as description and accessRestriction are always mirrored.
If federation.uuid has a non-empty value, the federation tokens are displayed in the log file and are visible, to administrators, in the web ui.
Once you have properly setup your uuid and can see your federation tokens, you are ready to share them with a pulling Gitblit instance.
The registration process can be partially automated by sending a federation proposal to another Gitblit instance.
To send a proposal:
Not all Gitblit instances accept federation proposals, there is a setting which allows Gitblit to outright reject them. In this case an email or instant message to the administrator of the other Gitblit instance is required. :)
If your proposal is accepted, the proposal is cached to disk on the remote Gitblit server and, if properly configured, the administrators of that Gitblit server will receive an email notification of your proposal.
Your proposal includes:
Submitting a proposal does not automatically register your server with the remote Gitblit instance.
Registration is a manual process for an administrator.
If your Giblit instance has received a federation proposal, you will be alerted to that information the next time you login to Gitblit as an administrator.
You may view the details of a proposal from scrolling down to the bottom of the repositories page and selecting a proposal. Sample registration settings will be generated for you that you may copy & paste into either your gitblit.properties file or your web.xml file.
You may exclude a repository from being pulled by a federated Gitblit instance by setting its federation strategy in the repository's settings page.
You may exclude repositories to pull in a federation registration. You may exclude all or you may exclude based on a simple fuzzy pattern. Only one wildcard character may be used within each pattern. Patterns are space-separated within the exclude and include fields.
federation.example.exclude = skipit.git
OR
federation.example.exclude = *
federation.example.include = somerepo.git someotherrepo.git
OR
federation.example.exclude = *
federation.example.include = common/* library/*
Below the repositories list on the repositories page you will find a section named federation registrations. This section enumerates the other gitblit servers you have configured to periodically pull. The status of the latest pull will be indicated on the left with a colored circle, similar to the status of an executed unit test or Hudson/Jenkins build. You can drill into the details of the registration to view the status of the last pull from each repository available from that source Gitblit instance. Additionally, you can specify the federation.N.notifyOnError=true flag, to be alerted via email of regressive status changes to individual registrations.
Source Gitblit instances can not directly track the success or failure status of Pulling Gitblit instances. However, the Pulling Gitblit instance may elect to send a status acknowledgment (*federation.N.sendStatus=true*) to the source Gitblit server that indicates the per-repository status of the pull operation. This is the same data that is displayed on the Pulling Gitblit instances ui.
A pulling Gitblit instance will periodically contact your Gitblit instance and will provide the token as proof that you have granted it federation access. Your Gitblit instance will decide, based on the supplied token, if the requested data should be returned to the pulling Gitblit instance. Gitblit data (user accounts, repository metadata, and server settings) are serialized as JSON using google-gson and returned to the pulling Gitblit instance. Standard Git clone and pull operations are used to transfer commits.
The federation process executes using an internal administrator account, $gitblit. All the normal authentication and authorization processes are used for federation requests. For example, Git commands are authenticated as $gitblit / token.
While the $gitblit account has access to all repositories, server settings, and user accounts, it is prohibited from accessing the web ui and it is disabled if federation.uuid is empty.
The federation feature should be considered a backdoor and enabled or disabled as appropriate for your installation.
Federated repositories defined in gitblit.properties are checked after Gitblit has been running for 1 minute. The next registration check is scheduled at the completion of the current registration check based on the registration's specified frequency.
After a repository has been cloned it is flagged as isFederated (which identifies it as being sourced from another Gitblit instance), isFrozen (which prevents Git pushes to this mirror) and federationStrategy=EXCLUDED (which prevents this repository from being pulled by another federated Gitblit instance).
During a federated pull operation, Gitblit does check that the origin of the local repository starts with the url of the federation registration.
If they do not match, the repository is skipped and this is indicated in the log.
By default all user accounts except the admin account are automatically pulled when using the ALL token or the USERS_AND_REPOSITORIES token. You may exclude a user account form being pulled by a federated Gitblit instance by checking exclude form federation in the edit user page.
The pulling Gitblit instance will store a registration-specific users.properties file for the pulled user accounts and their repository permissions. This file is stored in the federation.N.folder folder.
If you specify federation.N.mergeAccounts=true, then the user accounts from the source Gitblit instance will be integrated into the users.properties file of your Gitblit instance and allow sign-on of those users.
NOTE:
Upgrades from older Gitblit versions will not have the #notfederated role assigned to the admin account. Without that role, your admin account WILL be transferred with an ALL or USERS_AND_REPOSITORIES token.
Please consider setting that flag!
Server settings are automatically pulled when using the ALL token.
The pulling Gitblit instance will store a registration-specific gitblit.properties file for all pulled settings. This file is stored in the federation.N.folder folder.
These settings are unused by the pulling Gitblit instance.
Gitblit does not detect conflict and it does not offer conflict resolution of repositories, users, or settings.
If an object exists locally that has the same name as the remote object, it is assumed they are the same and the contents of the remote object are merged into the local object. If you can not guarantee that this is the case, then you should not store any federated repositories directly in git.repositoriesFolder and you should not enable mergeAccounts.
By default, federated repositories can not be pushed to, they are read-only by the isFrozen flag. This flag is ONLY enforced by Gitblit's JGit servlet. If you push to a federated repository after resetting the isFrozen flag or via some other Git access technique then you may break Gitblit's ability to continue pulling from the source repository. If you are only pushing to a local branch then you might be safe.
These examples would be entered into the gitblit.properties file of the pulling gitblit instance.
This assumes that the token is the ALL token from the source gitblit instance.
The repositories, example1_users.properties, and example1_gitblit.properties will be put in git.repositoriesFolder and the source user accounts will be merged into the local user accounts, including passwords and administrator status. The mirror instance will also send a status acknowledgment at the end of the pull operation which will include the state of each repository pull (EXCLUDED, SKIPPED, PULLED). This way the source Gitblit instance can monitor the health of its mirrors.
This example is considered nearly perfect because while the remote Gitblit's server settings are pulled and saved locally, they are not merged with your server settings so its not a true mirror, but its likely the mirror you'd want to configure.
federation.example1.url = https://go.gitblit.com
federation.example1.token = 6f3b8a24bf970f17289b234284c94f43eb42f0e4
federation.example1.frequency = 120 mins
federation.example1.folder =
federation.example1.mergeAccounts = true
federation.example1.sendStatus = true
This assumes that the token is the REPOSITORIES token from the remote gitblit instance.
The repositories will be put in git.repositoriesFolder/example2.
federation.example2.url = https://tomcat.gitblit.com/gitblit
federation.example2.token = 6f3b8a24bf970f17289b234284c94f43eb42f0e4
federation.example2.frequency = 120 mins
federation.example2.folder = example2
This assumes that the token is the REPOSITORIES token from the remote gitblit instance.
The repositories will be put in git.repositoriesFolder/example3.
federation.example3.url = https://tomcat.gitblit.com/gitblit
federation.example3.token = 6f3b8a24bf970f17289b234284c94f43eb42f0e4
federation.example3.frequency = 120 mins
federation.example3.folder = example3
federation.example3.exclude = somerepo.git
This assumes that the token is the REPOSITORIES token from the remote gitblit instance.
The repositories will be put in git.repositoriesFolder/example4.
federation.example4.url = https://tomcat.gitblit.com/gitblit
federation.example4.token = 6f3b8a24bf970f17289b234284c94f43eb42f0e4
federation.example4.frequency = 120 mins
federation.example4.folder = example4
federation.example4.exclude = *
federation.example4.include = somerepo.git