✎ infrastructure:server:webservers_nginx_flask_drupal_etc [NightOwl Wiki]

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===== Overview =====

We are running a number of things for the nightowl webserver.

- As a main webserver we run Nginx. This receives and handles all the initial http(s) requests.
- Nginx with fastcgi is used to handle php (with php5-fpm)
- gunicorn in combination with virtualenv is used to handle python wsgi webapplications. Each application runs on it's own socket. Nginx delegates all the requests to those applications using a reverse proxy (the request comes in at nginx on port 80 or 443, but nginx sends it on to another port on the same machine (127.0.0.1) where gunicorn is listening).
- circus is used to start the gunicorn apps, handle logging and restart them if necessary.

Webapplications we are running:
- drupal with mysql for nightowl.foundationu.com
- taiga (with gunicorn/circus behind nginx) and postgresql as database

===== Installing Circus =====

Install circus with 'pip install circus' (not inside a virtualenv). When running on a systemd linux distro (like debian and centos), create a systemd unit as documented on [[http://circus.readthedocs.io/en/latest/for-ops/deployment/|The circus website]] (forget about the upstart part, that is for ubuntu). But be sure to change /usr to /usr/local in the circus.service file (because we installed using pip).
Make sure you create the /etc/circus/ folder.

For information on running (monitoring) gunicorn (python wsgi) applications with circus, see [[http://docs.gunicorn.org/en/0.15.0/deploy.html#circus|The gunicorn with circus docs]] and [[https://github.com/taigaio/taiga-doc/blob/master/setup-production.adoc#61-circus-and-gunicorn|the taiga docs on circus]].

===== Running a Flask application with circus and gunicorn =====

Create a virtualenv (probably somewhere in a virtualhost folder under /srv/www/vhosts/<yourappdomain>.
Make sure you have gunicorn installed in your virtual env, and also all other dependencies for your flask app.

Add the following to /etc/circus/circus.ini making sure you change all references to your application (in the example in /srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/) and virtualenv and it's python library folder (here /srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/venv/ and /srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/venv/lib/python3.4/ respectively).

Also make sure you change the name of the app (here rfid).
Lastly make sure the port number (8001 in this case) is unique. Choose a unique port number (starting form 8001) for each application and change both the nginx and circus config accordingly.

```
[watcher:rfid]
working_dir = /srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/
cmd = gunicorn
args = -b 127.0.0.1:8001 app
uid = www-data
numprocesses = 1
autostart = true

[env:rfid]
PATH = /srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/venv/bin/:$PATH
TERM=rxvt-256color
SHELL=/bin/bash
USER=www-data
LANG=en_US.UTF-8
HOME= /srv/www/vhosts/rfid_test_nightowl_foundationu_com/
PYTHONPATH=/srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/venv/lib/python3.4/site-packages:/srv/www/vhosts/rfid_test_nightowl_foundationu_com/inventory/
```
===== Setting up nginx to reverse-proxy a python wsgi (gunicorn) application
 =====
Follow the basic setup from [[https://www.digitalocean.com/community/tutorials/how-to-serve-flask-applications-with-gunicorn-and-nginx-on-ubuntu-14-04#configuring-nginx-to-proxy-requests|Digital Ocean]]
 but instead of using "http://unix:" for the proxy pass directive, use http://127.0.0.1:<portnumber> as you configured in circus.ini.