Git

From OpenFlow Wiki

Git

You may have noticed by now that the OpenFlow team at Stanford uses Git extensively. Git is a distributed version control system designed to handle very large projects with speed and efficiency.

To install Git in a Debian system, run

apt-get install git-core

Making Changes to Projects (Starting a New Branch)

Being a distributed version control system, git allows you to make changes without have write access to the remote repository you cloned from. It is usually a good habit to start a new branch from an existing branch in this case, by executing

git branch <new branch name> <existing branch name>
git checkout <new branch name>

To see all the branches available in your local and remote repositories, run

git branch -a

This new branch can now be pushed to a remote repositories and subsequently merged into the master branch if so desired.

Adding Remote Repository to Local

Instructions provided often assumed a clean copy of the code from our repositories, e.g.,

git clone <git repo>

This might not be true, and a remote repository can be added to an existing local one easily, using

git remote add <repo name> <git repo>
git remote update

Now, you can see all the repository using

git branch -a

Gitosis

Gitosis allows us to provide write access to our Git repositories without having to provide shell accounts to our servers. This minimizes our management task while allowing others to push their improvements and bug fixes to our repositories. The latter is very much encouraged for most (if not all) our projects.

Getting Write Access to Git Repositories

If you have ready to be pushed into the repository and would like write access, you will first need to get write access to the repository. Email David Erickson the following in an email

• attach a public SSH key (with extension .pub), generated using ssh-keygen
• specify the repository you would like write access to, and why
• specify the person in Stanford that can validate the request (and cc the email to that person)

Allow Dave has added your public key to the system, you have to configure your local machine. In ~/.ssh/config, have a section like this

Host openflowswitch.org
       User git
       Port 22
       Hostname openflowswitch.org
       IdentityFile ~/.ssh/<key name>_rsa
       TCPKeepAlive yes
       IdentitiesOnly yes

Test the setup by running

ssh git@openflowswitch.org

You should see reply

PTY allocation request failed on channel 0
ERROR:gitosis.serve.main:Need SSH_ORIGINAL_COMMAND in environment.
                         Connection to openflowswitch.org closed.

Adding Write Access with Git through Shell Account

Unlike public Git access, Gitosis access to the repository clones the repository using

git clone git@openflowswitch.org:<repo name>.git

instead of

git clone git://openflowswitch.org/<repo name>.git

Note the different in the git url. See #Adding_Remote_Repository_to_Local for instructions in adding this as an additional remote repository.