Serving a Git repository over HTTP

Mohammad Altaleb — Mon, 13 May 2019 11:03:15 +0000

A while ago, I was assigned the task of researching how to serve a Git repository over HTTP. The tutorials and documentations I've found were either messy or incomplete.

After a painful process, I got it to work. But, unfortunately a decision was made to use a different approach to serve the repo.

I didn't want to just throw the effort away. So, here's a blog post about it.

The setup

We'll use Apache web server to serve the repository, and we'll install it on an Ubuntu 16.04.5 machine (AWS EC2 instance in my case).

Installation

Let's start by installing Git and Apache

sudo apt-get update
sudo apt-get install git-core
sudo apt-get install apache2

Creating the repo

For this tutorial, we will create a new Git repository in the documents root (/var/www/html)

cd /var/www/html
mkdir git
cd git
mkdir reponame
cd reponame
git init --bare
chgrp -R www-data /var/www/html/git
chown -R www-data /var/www/html/git

If you want to allow other people to push to the repo, open the file named config which was added to the repository by Git and append the following to it

[http]
    receivepack = true

Authentication

We only want authenticated users to access the repo. So, first we'll create a dummy bash script named auth.sh in (/usr/local/bin/):

cd /usr/local/bin/
touch auth.sh
chmod 755 auth.sh

The script will check a given username and password and exit with 0 code if they are correct or 1 otherwise.
The content of the script is the following:

#! /bin/bash
read user
read password

if [[ ("$user" = "hello") && ("$password" = "world") ]]; then
  exit 0
else
  exit 1
fi

To be able to use our script with Apache, we should install the package libapache2-mod-authnz-external that allows authentication against external services

apt-get install libapache2-mod-authnz-external

Then, we'll make sure the authentication module is enabled

a2enmod authnz_external

Configuring Apache

create an Apache configuration file with the name httpd.conf in (/etc/apache2/)

cd /etc/apache2/
touch httpd.conf

The content of httpd.conf should be the following:

<VirtualHost *:80>

    SetEnv GIT_PROJECT_ROOT /var/www/html/git
    SetEnv GIT_HTTP_EXPORT_ALL
    SetEnv REMOTE_USER=$REDIRECT_REMOTE_USER

    DocumentRoot /var/www/html
    <Directory "/var/www/html">
        Options All Includes Indexes FollowSymLinks
        Order allow,deny
        Allow from all
        AllowOverride All
    </Directory>


    ScriptAliasMatch \
        "(?x)^/git/(.*/(HEAD | \
        info/refs | \
        objects/(info/[^/]+ | \
        [0-9a-f]{2}/[0-9a-f]{38} | \
        pack/pack-[0-9a-f]{40}\.(pack|idx)) | \
        git-(upload|receive)-pack))$" \
        "/usr/lib/git-core/git-http-backend/$1"

    Alias /git /var/www/html/git

    <Directory /usr/lib/git-core>
        Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
        AuthType Basic
        AuthName "Restricted"
        AuthBasicProvider external
        AuthExternal auth
        require valid-user
    </Directory>

    <Directory /var/www/html/git>
        Options +ExecCGI +Indexes +FollowSymLinks
        Allowoverride None
        AuthType Basic
        AuthName "Restricted"
        AuthBasicProvider external
        AuthExternal auth
        require valid-user
    </Directory>

    AddExternalAuth auth /usr/local/bin/auth.sh
    SetExternalAuthMethod auth pipe

</VirtualHost>

Now, open /etc/apache2/apache2.conf file and comment out the line:

IncludeOptional sites-enabled/*.conf

Then, add the line:

Include /etc/apache2/httpd.conf

Enable mod_cgi, mod_alias and mod_env

a2enmod cgi alias env

Finally, update the repo and restart Apache

cd /var/www/html/git/reponame
git update-server-info

service apache2 restart

Testing

On your machine, clone the repository

git clone http://{SERVER_DOMAIN}/git/reponame/

Add something to the repo and commit it

touch test.txt
git add test.txt 
git commit -m "test commit"

Push the changes to the remote repository

git push -u origin master

And that's about it. If the clone and push succeed, it means we successfully served our repository.