To collaborate in a distributed development process you’ll need to push code to remotely accessible repositories.

This is somewhat of a follow-up to the previous article setting up a new rails app with git.

For the impatient

Set up the new bare repo on the server:

$ ssh myserver.com
Welcome to myserver.com!
$ mkdir /var/git/myapp.git && cd /var/git/myapp.git
$ git --bare init
Initialized empty Git repository in /var/git/myapp.git
$ exit
Bye!

Add the remote repository and push:

$ cd ~/Sites/myapp
$ git remote add origin ssh://myserver.com/var/git/myapp.git
$ git push origin master

Set the local master branch to track the remote branch.

Read further for a step-by-step explanation of what’s going on.

Pre-flight sanity check

Setting up a remote repository is fairly simple but somewhat confusing at first. Firstly, let’s check out what remote repositories are being tracked in our git repo:

$ cd ~/Sites/myapp
$ git remote

None. Looking good. Now let’s list all the branches:

$ git branch -a
* master

Just one branch, the master branch. Let’s have a look at .git/config:

$ cat .git/config
[core]
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true

A pretty bare-minimum config file.

Creating the bare remote repository

Before we can push our local master branch to a remote repository we need to create the remote repository. To do this we’ll ssh in and create it on the server:

$ ssh myserver.com
Welcome to myserver.com!
$ cd /var/git
$ mkdir myapp.git
$ cd myapp.git
$ git --bare init
Initialized empty Git repository in /var/git/myapp.git
$ exit
Bye!

A short aside about what git means by bare: A default git repository assumes that you’ll be using it as your working directory, so git stores the actual bare repository files in a .git directory alongside all the project files. Remote repositories don’t need copies of the files on the filesystem unlike working copies, all they need are the deltas and binary what-nots of the repository itself. This is what “bare” means to git. Just the repository itself.

Adding the remote repository to our local git repository configuration

Now that we’ve created the remote repository we’ll add it to our local repository as a remote server called “origin” using git remote add, which is just a nicer way of updating our config file for us:

$ git remote add origin ssh://myserver.com/var/git/myapp.git

Let’s see what it added to the config file:

[core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true
[remote "origin"]
    url = ssh://myserver.com/var/git/myapp.git
    fetch = +refs/heads/*:refs/remotes/origin/*

We now have a remote repository “origin” that will fetch all of it’s refs/heads/* branches and store them in our local repo in refs/remotes/origin/* when a git fetch is performed.

Pushing to the remote repository

The time has come to push our local master branch to the origin’s master branch. We do that using the git push <target> <local> command.

$ git push origin master
updating 'refs/heads/master'
  from 0000000000000000000000000000000000000000
  to   b379203bc187c2926f44a71eca3f901321ea42c6
 Also local refs/remotes/origin/master
Generating pack...
Done counting 1374 objects.
Deltifying 1374 objects...
 100% (1374/1374) done
Writing 1374 objects...
 100% (1374/1374) done
Total 1374 (delta 89), reused 0 (delta 0)
refs/heads/master: 0000000000000000000000000000000000000000 -> b379203bc187c2926f44a71eca3f901321ea42c6

and that’s all, folks. Further pushes can be done by repeating the git push command.

Now you can tell your co-conspirators to:

$ git clone ssh://myserver.com/var/git/myapp.git

and push and pull to your heart’s content.

Track the remote branch

You can specify the default remote repository for pushing and pulling using git-branch’s track option. You’d normally do this by specifying the --track option when creating your local master branch, but as it already exists we’ll just update the config manually like so:

[branch "master"]
    remote = origin
    merge = refs/heads/master

Now you can simply git push and git pull.

Sharing the remote repository with the world

If you want to set it up as a public repository be sure to check out the Git manual’s chapter on public git repositories.

Working with remote repository branches

git remote show is used to inspect a remote repository. It goes and checks the remote repository to see what branches have been added and removed since the last git fetch.

Doing a git remote show at the moment only shows us the remote repo’s master branch which we pushed earlier:

$ git remote show origin
* remote origin
  URL: ssh://myserver.com/var/git/myapp.git
  Tracked remote branches
    master

Let’s create a new local git repository and push to a new branch on the remote repository. We can then use git remote show to see the new remote branch, git fetch to mirror it into our local repo and git checkout --track -b to create a local branch to do some work on it.

We’ll start by creating a new local repo and pushing some code to a new branch in the remote repository.

$ mkdir /tmp/other-git
$ cd /tmp/other-git
$ git init
Initialized empty Git repository in /tmp/other-git
$ git remote add origin ssh://myserver.com/var/git/myapp.git
$ echo "Rails 2... woo" > afile
$ git add afile
$ git commit -m "Added afile" 
Created initial commit 0ac9a74: Added afile
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 something
$ git push origin master:refs/heads/dev/rails-2
updating 'refs/heads/rails-2' using 'refs/heads/master'
  from 0000000000000000000000000000000000000000
  to   0ac9a7457f4b21c9e058d4c54d262584bf35e528
 Also local refs/remotes/origin/rails-2
Generating pack...
Done counting 3 objects.
Deltifying 3 objects...
 100% (3/3) done
Writing 3 objects...
 100% (3/3) done
Total 3 (delta 0), reused 0 (delta 0)
Unpacking 3 objects...
 100% (3/3) done
refs/heads/rails-2: 0000000000000000000000000000000000000000 -> 0ac9a7457f4b21c9e058d4c54d262584bf35e528

Now let’s switch back to our old git repository and see if it detects the new branch on the remote repository:

$ git remote show origin
* remote origin
  URL: ssh://myserver.com/var/git/myapp.git
  New remote branches (next fetch will store in remotes/origin)
    dev/rails-2
  Tracked remote branches
    master

Let’s update our mirror of the remote repository by doing a git fetch:

$ git fetch
* refs/remotes/origin/master: storing branch 'dev/rails-2' of ssh://myserver.com/var/git/myapp.git
  commit: b379203
$ git remote show origin
* remote origin
  URL: ssh://myserver.com/var/git/myapp.git
  Tracked remote branches
    master
    dev/rails-2

We should now be able to see this in a our list of remote branches:

$ git branch -a
* master
origin/dev/rails-2
origin/master

If we then wanted to do some work on this remote dev/rails-2 branch we create a new local tracking branch like so:

$ git checkout --track -b dev/rails-2 origin/dev/rails-2
Branch dev/rails-2 set up to track remote branch refs/remotes/origin/dev/rails-2.
Switched to a new branch "dev/rails-2" 

To keep up-to-date and push new changesets we simply use git push and git pull when working in the local dev/rails-2 branch.

Also notice, like we manually changed for master, .git/config has a new entry for this new tracking branch:

[branch "dev/rails-2"]
    remote = origin
    merge = refs/heads/dev/rails-2

Further Reading

Sourcemage’s Git Guide has some very very handy real-life examples of git commands you’ll often need.