Uwsgi

Lots of confusion going around on the net about installing and using uwsgi. Here my notes.

Used documentation

https://github.com/unbit/uwsgi/issues/1688

https://www.digitalocean.com/community/tutorials/how-to-deploy-python-wsgi-applications-using-uwsgi-web-server-with-nginx

https://stackoverflow.com/questions/35262299/uwsgi-emperor-mode-not-working-outside-of-virtualenv

Installing

• pip3 install uwsgi
• pip3 install flask

Configuration

/etc/uwsgi-emperor/emperor.ini

[uwsgi]
 autoload = true
 no-orphan = true
 emperor = /etc/uwsgi-emperor/vassals
 master = true
 emperor-nofollow = true
 processes = 1
 workers = 2
 uid = www-data
 gid = www-data
 pidfile = /run/uwsgi/pid
 socket = /tmp/%n.sock
 chmod-socket = 666
 chown-socket = www-data
 log-date = false

For all applications you can use this configuration file in /etc/uwsgi-emperor/vassels/app1.ini. uwsgi is installed using pip so no loading of a python module is needed.

[uwsgi]
 master = false
 processes = 1
 pidfile = /run/uwsgi/%n.pid
 vaccum = true
 chmod-socket = 666
 socket = /tmp/%n.sock
 uid = www-data
 gid = www-data
 pythonpath = /opt/flask/%n
 module = %n

The %n will be replaced by the first part of the file-name (app1 in this example). In /opt/flask/app1 you can put your code.

Raspberry pi

On my raspberry pi uwsgi was installed with some extensions to ease configuration. E.g. to use .xml file for configuration. It was also not installed by pip so the uwsgi-plugin-python3 needed to be installed too.

/etc/uwsgi/apps-available/emperor.xml

 <uwsgi>
  <autoload>true</autoload>
  <no-orphan>true</no-orphan>
  <emperor>/etc/uwsgi/vassals-enabled</emperor>
  <master>true</master>
  <emperor-nofollow>true</emperor-nofollow>
  <processes>1</processes>
  <uid>www-data</uid>
  <gid>www-data</gid>
 </uwsgi>

/etc/uwsgi/apps-available/apps.xml

 <uwsgi>
  <plugins>python3</plugins>
  <master>false</master>
  <processes>1</processes>
  <vaccum>true</vaccum>
  <chmod-socket>666</chmod-socket>
  <socket>/tmp/%n.sock</socket>
  <uid>www-data</uid>
  <gid>www-data</gid>
  <pythonpath>/var/www/flask/%n</pythonpath>
  <module>%n</module>
 </uwsgi>

Make them available

cd /etc/uwsgi/apps-enabled
ln -s ../apps-available/emperror.xml
cd /etc/uwsgi/vassals-enabled
ln -s ../apps-available/apps.xml app1.xml
ln -s ../apps-available/apps.xml app2.xml

Daemon management

/usr/local/bin/uwsgi -d --ini /etc/uwsgi-emperor/emperor.ini --log-syslog

Start with logging to rsyslog, add following line to the rsyslogd configuration

:programname, contains, "uwsgi" /var/log/uwsgi/uwsgi.log

kill `pidof uwsgi`

This works for stopping all processes.

uwsgi --stop /run/uwsgi/pid

This looks cleaner but does not work on my system

uwsgi --reload /run/uwsgi/app1.pid

Restart a vassel (application)

kill -1 `cat /run/uwsgi/app1.pid`

Restart a vassel (application)