gitlab-org--gitlab-foss/doc/install/databases.md

Databases:

GitLab use MySQL as default database but you are free to use PostgreSQL.

MySQL

sudo apt-get install -y mysql-server mysql-client libmysqlclient-dev

# Login to MySQL
$ mysql -u root -p

# Create the GitLab production database
mysql> CREATE DATABASE IF NOT EXISTS `gitlabhq_production` DEFAULT CHARACTER SET `utf8` COLLATE `utf8_unicode_ci`;

# Create the MySQL User change $password to a real password
mysql> CREATE USER 'gitlab'@'localhost' IDENTIFIED BY '$password';

# Grant proper permissions to the MySQL User
mysql> GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER ON `gitlabhq_production`.* TO 'gitlab'@'localhost';

PostgreSQL

sudo apt-get install -y postgresql-9.1 postgresql-server-dev-9.1

# Connect to database server
sudo -u postgres psql -d template1

# Add a user called gitlab. Change $password to a real password
template1=# CREATE USER gitlab WITH PASSWORD '$password';

# Create the GitLab production database & grant all privileges on database
template1=# CREATE DATABASE gitlabhq_production OWNER gitlab;

# Quit from PostgreSQL server
template1=# \q

# Try connect to new database
sudo -u gitlab psql -d gitlabhq_production

Select the database you want to use

# Mysql
sudo -u gitlab cp config/database.yml.mysql config/database.yml

# PostgreSQL
sudo -u gitlab cp config/database.yml.postgresql config/database.yml

# make sure to update username/password in config/database.yml

Install gems

# mysql
sudo -u gitlab -H bundle install --without development test postgres  --deployment

# or postgres
sudo -u gitlab -H bundle install --without development test mysql --deployment