add deployment documentation for Python frontend

[nominatim.git] / docs / admin / Deployment-Python.md

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+# Deploying the Nominatim Python frontend
+
+The Nominatim can be run as a Python-based web application. You have the
+choice between [Falcon](https://falcon.readthedocs.io/en/stable/)
+and [Starlette](https://www.starlette.io/) as the ASGI framework.
+
+This section gives a quick overview on how to configure Nginx to server
+Nominatim. Please refer to the documentation of
+[Nginx](https://nginx.org/en/docs/) for background information on how to configure it.
+
+!!! Note
+    Throughout this page, we assume that your Nominatim project directory is
+    located in `/srv/nominatim-project` and that you have installed Nominatim
+    using the default installation prefix `/usr/local`. If you have put it
+    somewhere else, you need to adjust the commands and configuration
+    accordingly.
+
+    We further assume that your web server runs as user `www-data`. Older
+    versions of CentOS may still use the user name `apache`. You also need
+    to adapt the instructions in this case.
+
+### Installing the required packages
+
+The recommended way to deploy Python ASGI application is to run
+the ASGI runner (uvicorn)[https://uvicorn.org/]
+together with (gunicorn)[https://gunicorn.org/] HTTP server. We use
+Falcon here as the web framework.
+
+Create a virtual environment for the Python packages and install the necessary
+dependencies:
+
+``` sh
+sudo apt install virtualenv
+virtualenv /srv/nominatim-venv
+/srv/nominatim-venv/bin/pip install SQLAlchemy PyICU psycopg[binary]\
+   psycopg2-binary python-dotenv PyYAML falcon uvicorn gunicorn
+```
+
+### Setting up Nominatim as a systemd job
+
+Next you need to set up the application that serves Nominatim. This is
+easiest done with a systemd job.
+
+Create the following file `/etc/systemd/system/nominatim.service`:
+
+``` systemd
+[Unit]
+Description=Nominatim running as a gunicorn application
+After=network.target
+Requires=nominatim.socket
+
+[Service]
+Type=simple
+Environment="PYTHONPATH=/usr/local/lib/nominatim/lib-python/"
+User=www-data
+Group=www-data
+WorkingDirectory=/srv/nominatim-project
+ExecStart=/srv/nominatim-venv/bin/gunicorn -b unix:/run/nominatim.sock -w 14 -k uvicorn.workers.UvicornWorker nominatim.server.falcon.server:run_wsgi
+ExecReload=/bin/kill -s HUP $MAINPID
+StandardOutput=append:/ssd/nominatim/log/gunicorn.log
+StandardError=inherit
+PrivateTmp=true
+TimeoutStopSec=5
+KillMode=mixed
+
+[Install]
+WantedBy=multi-user.target
+```
+
+Make the new service known to systemd and start it:
+
+``` sh
+sudo systemctl daemon-reload
+sudo systemctl enable nominatim
+sudo systemctl start nominatim
+```
+
+This sets the service up, so that Nominatim is automatically started
+on reboot.
+
+### Configuring nginx
+
+To make the service available to the world, you need to proxy it through
+nginx. Add the following definition to the default configuration:
+
+``` nginx
+upstream nominatim_service {
+  server unix:/run/nominatim.sock fail_timeout=0;
+}
+
+server {
+    listen 80;
+    listen [::]:80;
+
+    root /var/www/html;
+    index /search;
+
+    location / {
+            proxy_set_header Host $http_host;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            proxy_redirect off;
+            proxy_pass http://nominatim_service;
+    }
+}
+```
+
+Reload nginx with
+
+```
+sudo systemctl reload nginx
+```
+
+and you should be able to see the status of your server under
+`http://localhost/status`.