uwsgi zero downtime restart config Zerg Dance

nginx.conf

# nginx.conf

# the upstream component nginx needs to connect to
upstream my_project {
    server 127.0.0.1:3031
}

# configuration of the server
server {
    # the port your site will be served on
    listen      8082;
    # the domain name it will serve for
    charset     utf-8;

    # max upload size
    client_max_body_size 200M;   # adjust to taste

    location / {
        uwsgi_pass  my_project;
        include     /etc/nginx/uwsgi_params;
        uwsgi_read_timeout 300;
    }
}

uwsgi.ini

# uwsgi ini file
[uwsgi]
# http://stackoverflow.com/questions/14194859/importerror-no-module-named-django-core-wsgi-for-uwsgi
project_name = my_app
# Django-related settings
# the base directory (full path)
chdir           = %d
# the absolute path of the directory containing the configuration file
# http://uwsgi-docs.readthedocs.io/en/latest/Configuration.html
# %n	the filename without extension
# process-related settings
# master
module          = app
;master          = true
# maximum number of worker processes
# adjust according to http://uwsgi-docs.readthedocs.io/en/latest/ThingsToKnow.html
processes       = 10
max-requests    = 15
# the socket (use the full path to be safe
;socket          = /tmp/%(project_name).sock
# ... with appropriate permissions - may be needed
chmod-socket    = 666
#chown-socket    = www-data:www-data
# clear environment on exit
vacuum          = true
daemonize       = /tmp/%(project_name).log
pidfile         = /tmp/%(project_name).pid
# added 2014-08-25
#emperor         = /etc/uwsgi/vassals
#uid             = www-data
#gid             = www-data
# added 2014-09-17
reload-on-as    = 126
reload-on-rss   = 126
enable-threads  = true
pythonpath      = %d
# the absolute path of the directory containing the configuration file
env             = LANG=en_US.UTF-8
# http://stackoverflow.com/questions/10396141/strange-unicodeencodeerror-using-os-path-exists
stats           = /tmp/%(project_name)_stats.sock
; fifo '0'
master-fifo = /var/run/new.fifo
; fifo '1'
master-fifo = /var/run/running.fifo
; fifo '2'
master-fifo = /var/run/sleeping.fifo
; attach to zerg
zerg = /var/run/pool1

; hooks
; destroy the currently sleeping instance
if-exists = /var/run/sleeping.fifo
  hook-accepting1-once = writefifo:/var/run/sleeping.fifo Q
endif =
; force the currently running instance to became sleeping (slot 2) and place it in pause mode
if-exists = /var/run/running.fifo
  hook-accepting1-once = writefifo:/var/run/running.fifo 2p
endif =
; force this instance to became the running one (slot 1)
hook-accepting1-once = writefifo:/var/run/new.fifo 1

# destroy the running instance
# echo Q > /var/run/running.fifo

# unpause the sleeping instance and set it as the running one
# echo p2 > /var/run/sleeping.fifo

[uwsgi-m]
master = true
zerg-pool = /var/run/pool1:127.0.0.1:3031
daemonize       = /tmp/uwsgi_master.log
pidfile         = /tmp/uwsgi_master.pid

Ref
http://uwsgi-docs.readthedocs.io/en/latest/articles/TheArtOfGracefulReloading.html
http://zarnovican.github.io/2016/02/15/uwsgi-graceful-reload/
http://daniellombrana.es/blog/2015/07/01/gracefulreloading.html