HOWTO - Git server setup on ubuntu

ref:  https://git-scm.com/book/en/v2/Git-on-the-Server-Setting-Up-the-Server

1. create 'git' user and group

    $ sudo adduser git

2. create git users

    $ sudo useradd -M  adam # not create home directory

    $ sudo passwd  adam

    $ sudo usermod -G git  adam

    $ which git-shell

in /etc/passwd, replace /bin/bash with  /usr/bin/git-shell    # git-only ssh login

3. handle ssh keys

    $ su git
    $ cd
    $ mkdir .ssh && chmod 700 .ssh
    $ touch .ssh/authorized_keys && chmod 600 .ssh/authorized_keys 

    $ cat /tmp/id_rsa.adam.pub >> ~/.ssh/authorized_keys

4. create new project

    $ mkdir -p  /home/git

    $ chmod g-w /home/git        # make sure group has no write access

    $ cd /home/git

    $ git init --bare test.git

    $ chmod -R git:git test.git/ # double-check

    $ chmod -R 775 test.git/

# check project from user side

    $ git clone adam@serverip:/home/git/test.git

    $ cd test

    $ git remote -v