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Reverse Proxying to pgAdmin with uWSGI and NGINX

Yogesh Mahajan 12/16/2021
Thought leadership

pgAdmin 4 is a free open source graphical management tool for PostgreSQL and derivative relational databases such as EnterpriseDB's EDB Advanced Server. pgAdmin can be installed in two modes: Server mode and Desktop mode. pgAdmin in server mode can be deployed behind different web servers like apache2, Nnginx etc.

A reverse proxy is a server that sits in front of web servers and forwards client (e.g. web browser) requests to those web servers. Reverse proxies are typically implemented to help increase security and performance.

This blog will guide you to reverse proxy to pgAdmin using Nginx and uWSGI on Debian or Ubuntu Linux. The process is the same on other Linux distributions, but file, directory, and service names may differ.

Setup Python Environment and Install pgadmin

Let’s create a pgadmin app folder under /opt directory.

sudo mkdir -p /opt/pgadmin/

Switch to root user

sudo su -

Create a python virtual environment and activate it. 

python3 -m venv /opt/pgadmin/venv
source /opt/pgadmin/venv/bin/activate

Install pgadmin and uwsgi using the pip utility.

pip install pgadmin4
pip install uwsgi

Create directories used by pgAdmin.

mkdir /var/lib/pgadmin
mkdir /var/log/pgadmin

Run pgadmin's setup.py. Follow setup instructions until it's complete, and take note of your email and password created here.

python3 /opt/pgadmin/venv/lib/python3.8/site-packages/pgadmin4/setup.py
NOTE: Configuring authentication for SERVER mode.

Enter the email address and password to use for the initial pgAdmin user account:

Email address: pgadmin@example.com
Password: 
Retype password:
pgAdmin 4 - Application Initialisation
======================================

Add user pgadmin. This user account will be used to run the pgAdmin processes.

adduser --system --group --home /var/lib/pgadmin --disabled-login --shell /usr/sbin/nologin pgadmin

Allow user pgadmin to access directories: /var/log/pgadmin, /var/lib/pgadmin and /opt/pgadmin

chown -R pgadmin:pgadmin /var/log/pgadmin /var/lib/pgadmin/ /opt/pgadmin

pgAdmin should be completely set up by now.

Integrate uWSGI and pgAdmin

Now, we're ready to integrate pgAdmin and uWSGI, creating a WSGI server that listens at UNIX socket /tmp/pgadmin.sock. Create a uWSGI configuration file called pgadmin-on-uwsgi.ini inside the project folder /opt/pgadmin/. Add  contents below in the uWSGI configuration file.

vim /opt/pgadmin/pgadmin-on-uwsgi.ini
[uwsgi]
socket = /tmp/pgadmin4.sock
chdir = /opt/pgadmin/venv/lib/python3.8/site-packages/pgadmin4/
module = pgAdmin4:application
threads = 20
processes = 1
wsgi-file = pgAdmin4.wsgi
mount = /pgadmin4=pgAdmin4:app
manage-script-name = true
chmod-socket = 660

Setup uWSGI to run as a service using systemd

Let’s create a systemd service unit file. Creating a systemd unit file will allow Ubuntu’s init system to automatically start uWSGI and serve the pgadmin application whenever the server boots.

Create a unit file called pgadmin-on-uwsgi.service within the /etc/systemd/system directory. Contents of the service file looks like below.

vim /etc/systemd/system/pgadmin-on-uwsgi.service
[Unit]
Description=pgadmin4 on uWSGI
Requires=network.target
After=network.target
[Service]
User=pgadmin
Group=www-data
Environment="PATH=/opt/pgadmin/venv/bin"
ExecStart=/opt/pgadmin/venv/bin/uwsgi --ini /opt/pgadmin/pgadmin-on-uwsgi.ini
[Install]
WantedBy=multi-user.target

Start the uWSGI service created and enable it so that it starts at boot:

systemctl start pgadmin-on-uwsgi.service
systemctl enable pgadmin-on-uwsgi.service

uWSGI service status can be checked with command below:

systemctl status pgadmin-on-uwsgi.service

Configuring Nginx to Proxy Requests

The pgAdmin4 application server should now be up and running, waiting for requests on the socket file. Let’s configure Nginx to pass web requests to that socket using the uWSGI protocol.

Begin by creating a server block in a new pgadmin4.conf configuration file in Nginx’s sites-available directory: /etc/nginx/sites-available/. Tell Nginx to listen on port 80, and respond to any server name (sent by the client in the Host header).Here is code snippet for nginx pgadmin4.conf file

vim /etc/nginx/sites-available/pgadmin4.conf
server {
    listen 80;
    server_name _;
        location /pgadmin4/ {
            include /etc/nginx/uwsgi_params;
            uwsgi_pass unix:/tmp/pgadmin4.sock;
    }
}

To enable the Nginx server block configuration just created, link the file to the sites-enabled directory and restart the Nginx process to read the new configuration.

sudo ln -s /etc/nginx/sites-available/pgadmin4.conf /etc/nginx/sites-enabled/pgadmin4.conf
sudo systemctl restart nginx

You should now be able to navigate to pgadmin in your web browser with url - http://<ip_address>/pgadmin4:

Data transfer can be encrypted by adding SSL/TLS support to the configuration. Also http requests can be redirected to https.

After updating the pgadmin.conf to support encrypted stata transfer looks like below :

server {
    listen 80;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl;
    server_name _;
    ssl_certificate /etc/nginx/server.crt;
    ssl_certificate_key /etc/nginx/server.key;
    ssl_session_cache builtin:1000 shared:SSL:10m;
    ssl_protocols TLSv1.2;
    ssl_ciphers HIGH:!aNULL:!eNULL:!EXPORT:!CAMELLIA:!DES:!MD5:!PSK:!RC4;
    ssl_prefer_server_ciphers on;

    location /pgadmin4/ {
        include /etc/nginx/uwsgi_params;
        uwsgi_pass unix:/tmp/pgadmin4.sock;
    }
}

Conclusion

Users can use reverse proxy servers to provide an interface between their clients and the pgAdmin server. It's simple to configure SSL/TLS support or to host pgAdmin in a subdirectory.

Read MoreHow to Use Logical Replication in pgAdmin4

Yogesh Mahajan  is a Principal Software Engineer for EDB. His core competencies are in Python, Javascript, Java & cloud technologies AWS, Openstack, and Azure. Mahajan is also an AWS certified Solution Architect. He has been contributing to pgAdmin since 2019 in both development and test areas.