I am new to the git world, I have been using subversion for many of my past projects, so bear with me if I seem to cover rudimentary git in this document.

The goal of this document is to show you how to use cloud-init with ubuntu 12.10 to easily create a git server in the aws cloud.

Ubuntu 12.10

I would prefer to use 12.04 LTS for its longer support, however 12.04 does not have a new enough version of cloud-init installed for the features we will be using.

A list Ubuntu’s virtual machines, or AMIs in amazons language, can be found at http://uec-images.ubuntu.com/releases/ [1]

For this example I will be using an EBS backed AMI in the east-1 region. This AMIs id is ami-7539b41c

Cloud-init

AWS allows you to pass in script as a file or text when instantiating a server. This script will then be run during the creation process. You can for example send it a bash script and it will execute it just fine.

However, rather than using bash, there is new script language in town cloud-init https://help.ubuntu.com/community/CloudInit [2] One part of this is the cloud-config script. This idea is still in development, but it works well now, I believe their goal is to have a script more focused on “what would you do on initialization” . Focusing more on things like adding users, getting ssh keys set up etc.

I am not going to go into great depth on how to use cloud init, I am mostly just going to show you a script that works and explain that script a little. To see more examples you can go to the /usr/share/doc/cloud-init/examples folder on your ubuntu install and read the examples there.

Here is the cloud-config script I came up with to help create a git server in the AWS cloud. (replace the ssh keys and password with your own

#cloud-config

# This cloud-config file creates a git server

apt_update: true

apt_upgrade: true

# Add the git package

packages:

- git-core

# Add groups to the system

# The following example adds the ubuntu group with members foo and bar and

# the group cloud-users.

groups:

- git

- patman

# Add users to the system. Users are added after groups are added.

users:

- default

- name: git

shell: /usr/bin/git-shell

gecos: git user

primary-group: git

lock-passwd: true

ssh-import-id: None

# Add SSh keys for every user of the git repository

ssh-authorized-keys:

- ssh-rsa AAAAB3NzXXXX

# This is not "needed" I am just adding myself to the system as a user who can ssh into the box

- name: patman

shell: /bin/bash

gecos: Patrick Bailey

primary-group: patman

groups: admin

passwd: $6$aFXXXXXX

ssh-import-id: None

ssh-authorized-keys:

- ssh-rsa AAAABXXXX

# This is a work around to a but

# The users password is locked upon creation and should not be

# This just unlocks it

runcmd:

- [passwd, patman, '-u']

This script

· installs the git tool

· Create the git user

· Sets the git default shell to usr/bin/git-shell, this will allow git programs to work via ssh but not allow a shell to ssh into for users.

· Puts all the public SSH keys into the gits aurhorized_keys file

· Create the user “patman” with ssh access and a set password for the machine (the password is the encrypted password as seen in /etc/shadow

Save this file off as a script called

cloud-config-git.txt

Create the EC2 machine

The following assumes you have installed and are familiar with the AWS command line tools and have them installed on their system.

This also assumes that your default security group has port 22 open

Run the following command to instantiate this machine.

> ec2-run-instances ami-7539b41c -b /dev/sda1=:8:true -k pats-keypair -t t1.micro --availability-zone us-east-1a -f cloud-config-git.txt

The instance id should be displayed in this instance it is i-d3bd8da2

> ec2-describe-instances i-d3bd8da2

Copy the address

ec2-50-16-173-244.compute-1.amazonaws.com

Now since I created the patman user and gave it my ssh keys I can ssh like this

> ssh patman@ec2-50-16-173-244.compute-1.amazonaws.com

Instead of doing this (using the ubuntu user)

> ssh -i .work_ec2/pats-keypair.pem ubuntu@ec2-50-16-173-244.compute-1.amazonaws.com

Create a location to put the git repositories

From the aws server run the following commands

> sudo mkdir -p /opt/git

> sudo chown git:git /opt/git

Now place a “bare project” in this folder for each of projects you want this server to act as a origin master for. More information can be found here on how to do this http://git-scm.com/book/en/Git-on-the-Server-Getting-Git-on-a-Server [3]

Assuming you have a git project called my_git_project.git

> sudo su -s /bin/bash git

> cd /opt/git

> mkdir my_git_project.git

> cd my_git_project.git

> git --bare init

From my understanding the --bare init creates a shell git project for you to later push to.

This git “origin master” server should be ready to go!

Push your git project to this master

Now from your local machine upload your project.

If you do not have a local project here is a quick few commands to create one.

> git init my_git_project.git

> cd my_git_project

> touch test_file.txt

> git add *

> git commit -m "initial commit"

Set the origin

> git remote add origin git@ec2-50-16-173-244.compute-1.amazonaws.com:/opt/git/my_git_project.git

Now view the remote connection to make sure it is correct.

> git remote -v

In case you need to edit this you can remove the origin by running the command “git remote rm origin” Oh, and origin is not a special name you could use bob instead if you like, or whatever makes sense for you.

Before uploading this repository to the git server you can check to see if anything needs to be checked in

> git status