To install Odoo for production, you need to carry out the following steps:

1. As root, install and build the following dependencies:

# apt-get update
# apt-get install git python3.5 postgresql nano virtualenv 
      gcc python3.5-dev libxml2-dev libxslt1-dev 
      libevent-dev libsasl2-dev libldap2-dev libpq-dev 
      libpng-dev libjpeg-dev 
      xfonts-75dpi xfonts-base wget xz-utils
# wget -O wkhtmltox.tar.xz 
https://github.com/wkhtmltopdf/wkhtmltopdf/releases/download/0.12.4/wkhtmltox-0.12.4_linux-generic-amd64.tar.xz 
# tar xvf wkhtmltox.tar.xz
# mv wkhtmltox/lib/* /usr/local/lib/
# mv wkhtmltox/bin/* /usr/local/bin/
# mv wkhtmltox/share/man/man1 /usr/local/share/man/

2. As root, create a user called odoo:

    # adduser odoo  

3. Configure the PostgreSQL database:

    # sudo -u postgres createuser odoo
    # sudo -u postgres createdb -O odoo odoo_project 

4. As odoo, clone the project repository:

    # su odoo
    $ mkdir ~/odoo-prod
    $ cd ~/odoo-prod
    $ git clone https://github.com/yourlogin/project.git project
    $ mkdir -p project/src

5. As the odoo user, clone the Odoo source code:

    $ cd project/src
    $ git clone -b 12.0 --single-branch   
    https://github.com/odoo/odoo.git odoo  

6. Create virtualenv and install the dependencies:

    $ virtualenv -p python3 ~/env-odoo-12.0
    $ source ~/env-odoo-12.0/bin/activate
    $ pip3 install -r odoo/requirements.txt  

7. Clone all third-party add-on repositories in the project/src subdirectory:

    $ git clone -b 12.0 https://github.com/OCA/partner-contact.git

8. Create the ~/odoo-prod/project/bin directory:

    $ mkdir ~/odoo-prod/project/bin  

9. Create a script to easily start Odoo in the production environment in ~/odoo-prod/project/bin/start-odoo:

    #! /bin/sh
    PYTHON=~env-odoo-12.0/bin/python3 
    ODOO=~odoo/odoo-prod/project/src/odoo/odoo-bin
    CONF=~odoo/odoo-prod/project/production.conf
    ${PYTHON} ${ODOO} -c ${CONF} "$@"

10. Make the script executable:

   $ chmod +x ~/odoo-prod/project/bin/start-odoo

11. As root, uninstall gcc:

   # apt-get remove gcc