GIT itself

apt-get install git
adduser --disabled-login --gecos 'Gitea' git

GITEA app

cd /mnt/gitea/
wget https://dl.gitea.io/gitea/1.4.0/gitea-1.4.0-linux-arm-7 -O gitea
chmod +x gitea
chown -R git: /mnt/gitea

check its running at https://192.X.X.X:3000 with : ./gitea web

GITEA systemd service

In /etc/systemd/system/gitea.service:

[Unit]
Description=Gitea (Git with a cup of tea)
After=syslog.target
After=network.target

[Service]
# Modify these two values ​​and uncomment them if you have
# repos with lots of files and get to HTTP error 500 because of that
###
# LimitMEMLOCK=infinity
# LimitNOFILE=65535
RestartSec=2s
Type=simple
User=git
Group=git
WorkingDirectory=/mnt/gitea
ExecStart=/mnt/gitea/gitea web
Restart=always
Environment=USER=git 
HOME=/mnt/gitea/gitea

[Install]
WantedBy=multi-user.target

enable service:

systemctl enable gitea.service
systemctl start gitea.service

reboot and check service is running.

Apache2

apt-get install -y apache2
a2enmod ssl rewrite actions alias proxy_fcgi proxy proxy_http

PostgreSQL

CREATE DATABASE gitea;
CREATE USER gitea_user WITH ENCRYPTED PASSWORD 'pass123';    
GRANT CONNECT ON DATABASE gitea TO gitea_user;
\c gitea;
GRANT USAGE ON SCHEMA public TO gitea_user;
GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA public TO gitea_user;
GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO gitea_user;

Setup Apache2 reverse proxy

a2enmod proxy
a2enmod proxy_http

Configure reverse proxy directives source :

ProxyPreserveHost On
ProxyRequests off
ProxyPass / http://localhost:3000/
ProxyPassReverse / http://localhost:3000/

gitea.com.conf file:

<VirtualHost *:80>
    ServerName mygitea.com
    Redirect permanent / https://mygitea.com
</VirtualHost>

<VirtualHost *:443>
    ServerName mygitea.com
    ProxyPreserveHost On
    ProxyRequests off
    ProxyPass / http://localhost:3000/
    ProxyPassReverse / http://localhost:3000/

    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/html
    SSLengine on
    SSLCertificateKeyFile /etc/letsencrypt/live/mygitea.com/privkey.pem
    SSLCertificateFile    /etc/letsencrypt/live/mygitea.com/cert.pem
    SSLCertificateChainFile /etc/letsencrypt/live/mygitea.com/fullchain.pem

    ErrorLog ${APACHE_LOG_DIR}/gitea-error.log
    CustomLog ${APACHE_LOG_DIR}/gitea-access.log combined
    Include conf-available/serve-cgi-bin.conf
</VirtualHost>

Configuration

from GUI

• disable registration form
• mark repo as private

from CLI

edit custom/conf/app.ini and systemctl restart gitea.service