Nginx – Configure basic python 3.5, flask, uwsgi, nginx app

flasknginxpythonuwsgiweb-server

Not sure where I am going wrong here, all I get is a 502 bad gateway. (server ip is 104.197.13.112)
The code for all the configuration files and basic app are in a github repo.
github repo

nginx seems to start correctly, uwsgi does not and I think my problem is with my uwsgi setup and uwsgi.ini. Also not in the log below, my virtual env is python 3.5 and below the error reports 3.4.2. I have uwsgi installed in my virtual env. (Update, I got the uwsgi installed in my virtual env to be run by the virtual env rather than the system python by sylinking the uwsgi in /usr/bin/uwsgi to the uwsgi in the env.) The log below reflects that but the error is otherwise the same

The log shows

(testenv)root@co-data-nginx-1:/# tail /var/log/uwsgi/app/flasktest.log
Wed Jan 13 03:39:39 2016 - uwsgi socket 1 bound to UNIX address /tmp/flasktest.sock fd 5
Could not find platform independent libraries <prefix>
Could not find platform dependent libraries <exec_prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Wed Jan 13 03:39:39 2016 - Python version: 3.5.1 |Continuum Analytics, Inc.| (default, Dec  7 2015, 11:16:01)  [GCC 4.4.7 20120313 (Red Hat 4.4.7-1)]
Wed Jan 13 03:39:39 2016 - Set PythonHome to /var/www/flasktest/testenv
Fatal Python error: Py_Initialize: Unable to get the locale encoding
ImportError: No module named 'encodings'
uwsgi does not start.

uwsgi does not start

(testenv)root@co-data-nginx-1:/# service uwsgi restart
Job for uwsgi.service failed. See 'systemctl status uwsgi.service' and 'journalctl -xn' for details.
(testenv)root@co-data-nginx-1:/# journalctl -xn
-- Logs begin at Tue 2016-01-12 23:46:30 UTC, end at Wed 2016-01-13 03:58:07 UTC. --
Jan 13 03:58:04 co-data-nginx-1 systemd[1]: Starting LSB: Start/stop uWSGI server instance(s)...
-- Subject: Unit uwsgi.service has begun with start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit uwsgi.service has begun starting up.
Jan 13 03:58:04 co-data-nginx-1 uwsgi[7065]: Starting app server(s): uwsgi -> ! failed!
Jan 13 03:58:04 co-data-nginx-1 systemd[1]: uwsgi.service: control process exited, code=exited status=1
Jan 13 03:58:04 co-data-nginx-1 systemd[1]: Failed to start LSB: Start/stop uWSGI server instance(s).
-- Subject: Unit uwsgi.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit uwsgi.service has failed.
--
-- The result is failed.
Jan 13 03:58:04 co-data-nginx-1 systemd[1]: Unit uwsgi.service entered failed state.
Jan 13 03:58:06 co-data-nginx-1 systemd[1]: Starting LSB: Start/stop uWSGI server instance(s)...
-- Subject: Unit uwsgi.service has begun with start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit uwsgi.service has begun starting up.
Jan 13 03:58:07 co-data-nginx-1 uwsgi[7207]: Starting app server(s): uwsgi -> ! failed!
Jan 13 03:58:07 co-data-nginx-1 systemd[1]: uwsgi.service: control process exited, code=exited status=1
Jan 13 03:58:07 co-data-nginx-1 systemd[1]: Failed to start LSB: Start/stop uWSGI server instance(s).
-- Subject: Unit uwsgi.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit uwsgi.service has failed.
--
-- The result is failed.
Jan 13 03:58:07 co-data-nginx-1 systemd[1]: Unit uwsgi.service entered failed state.

Trying test @gf_ suggested, run:

 uwsgi --ini /etc/uwsgi/apps-enabled/flasktest.ini

I get the output below, this looks good but (remember I am running as root) if I login as another user I can only run the above line is I ass sudo. If I do add sudo it does not work, getting bacicly thte same error as in the uwsgi log.

(testenv)root@co-data-nginx-1:/etc/uwsgi/apps-enabled# uwsgi --ini flasktest.ini
[uWSGI] getting INI configuration from flasktest.ini
*** Starting uWSGI 2.0.12 (64bit) on [Wed Jan 13 21:54:35 2016] ***
compiled with version: 4.9.2 on 12 January 2016 23:28:38
os: Linux-3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u2 (2016-01-02)
nodename: co-data-nginx-1
machine: x86_64
clock source: unix
detected number of CPU cores: 1
current working directory: /etc/uwsgi/apps-enabled
detected binary path: /var/www/flasktest/testenv/bin/uwsgi
!!! no internal routing support, rebuild with pcre support !!!
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) ***
chdir() to /var/www/flasktest
your processes number limit is 14779
your memory page size is 4096 bytes
detected max file descriptor number: 65536
VirtualHosting mode enabled.
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
uwsgi socket 0 bound to UNIX address /tmp/flasktest.sock fd 3
Python version: 3.5.1 |Continuum Analytics, Inc.| (default, Dec  7 2015, 11:16:01)  [GCC 4.4.7 20120313 (Red Hat 4.4.7-1)]
Set PythonHome to /var/www/flasktest/testenv
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x192cb40
your server socket listen backlog is limited to 100 connections
your mercy for graceful operations on workers is 60 seconds
mapped 436560 bytes (426 KB) for 5 cores
*** Operational MODE: preforking ***
WSGI app 0 (mountpoint='') ready in 0 seconds on interpreter 0x192cb40 pid: 17933 (default app)
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI master process (pid: 17933)
spawned uWSGI worker 1 (pid: 17935, cores: 1)
spawned uWSGI worker 2 (pid: 17936, cores: 1)
spawned uWSGI worker 3 (pid: 17937, cores: 1)
spawned uWSGI worker 4 (pid: 17938, cores: 1)
spawned uWSGI worker 5 (pid: 17939, cores: 1)

In /etc/uwsgi/apps-avalible (enabled) I have.

(testenv)root@co-data-nginx-1:/# cat /etc/uwsgi/apps-enabled/flasktest.ini
# To be put in /etc/uwsgi/apps-available and lnked to the apps-enabled
# mv /var/www/flasktest/config/flasktest.ini /etc/uwsgi/apps-available/
# and simlink into
# ln -s /etc/uwsgi/apps-available/flasktest /etc/uwsgi/apps-enabled

[uwsgi]
module = testapp
callable = app
vhost = true
venv = /var/www/flasktest/testenv
chdir = /var/www/flasktest
master = true
processes = 5
socket = /tmp/%n.sock
vacuum = true
die-on-term = true

And finally, here is the nginx setup, again all of this is in the github repo.

(testenv)root@co-data-nginx-1:/# cat /etc/nginx/sites-available/flasktest
# rm /etc/nginx/sites-available/default
# rm /etc/nginx/sites-enabled/default
# mv /var/www/flasktest/config/flasktest /etc/nginx/sites-available/
# and simlink into
# ln -s /etc/nginx/sites-available/flasktest /etc/nginx/sites-enabled

# now test setup
# nginx -t
# If it passes run
# service nginx restart

server {
    listen 80;
    server_tokens off;
    # ip address or domain
    # server_name www.mysite.com mysite.com
    server_name 104.197.13.112;

    location /static {
         alias /var/www/flasktest/static;
     }

     location / {
         include uwsgi_params;
         uwsgi_pass unix:///tmp/flasktest.sock;
         include uwsgi_params;
     }

nginx logs

2016/01/13 02:34:03 [error] 4417#0: *2 connect() to unix:///tmp/flasktest.sock failed (111: Connection refused) while connecting to upstream, client: 24.52.34.170, server: 104.197.13.112, request: "GET / HTTP/1.1", upstream: "uwsgi://unix:///tmp/flasktest.sock:", host: "104.197.13.112"
2016/01/13 02:34:04 [error] 4417#0: *2 connect() to unix:///tmp/flasktest.sock failed (111: Connection refused) while connecting to upstream, client: 24.52.34.170, server: 104.197.13.112, request: "GET /favicon.ico HTTP/1.1", upstream: "uwsgi://unix:///tmp/flasktest.sock:", host: "104.197.13.112", referrer: "http://104.197.13.112/"

Best Answer

Let's go...

Remove /var/www/flasktest/uwsgi.ini, you don't need this.
uwsgi:
- ...can't bind to your socket; change the socket directive in your uwsgi.ini to /tmp/%n.sock. %n will get evaluated to the name of the config file, sans extension.
- Does uwsgi work if you start it? Have a look inside the logs; if you'll find errors, please post these.
Nginx:
- Change your uwsgi_pass directive to uwsgi_pass unix:///tmp/flasktest.sock and insert include uwsgi_params; at the next line.
- Reverse the order of the / and /static config blocks to make sure these work as expected. As it stands, / will be hit for all requests, including /static, so these would be served by your backend, which isn't wise to do, given the files being served are static and not dynamic.

Related Solutions

Nginx + uWSGI on localhost always gives 502 Bad Gateway. Any ideas how to solve this

I saw your post yesterday, just searching for an answer for exactly the same issue. Finally, today I reached the root of the problem.

I suppose you specify the chdir in your .ini config file as the directory where your project is located. I mean that if for example your project is 'myproject' and you have it in '/var/www/myproject' directory, you specify '/var/www' as the chdir.

So, the path for all internal resources is not well defined, and Python interpereter (may be you are using Django?) does not reach them. Ok, I will explain how a solution works in a Django project. For example, suppose that you have an app inside your project called 'app1'; in your views module you are calling for a forms defined in your forms module; you will be doing this like that:

from app1.forms import *

okay? Well, the thing is that the path is not well defined for uwsgi. You should now define this like that:

from myproject.app.forms import *

and you will see that everything is working now. No more 502 Bad Gateway errors will appear for you :)

Yes, I know that is not very elegant to add 'myproject.' to every internal resource calling. So, you can simply add this to your 'settings.py' file:

sys.path.append('/var/www/myproject/')

Substitute '/var/www/' for the path where your project is located on your machine. With this tiny solution, every started working for me :)

I hope my comment helps you.

Cheers, Jose

Ubuntu – Why is Upstart not starting uWSGI

Figure it out. Not sure I know how though. I think it was the LOGTO portion of the uwsgi.conf file that made it not work. This is my uwsgi emperor file now:

description "uWSGI Emperor"

start on runlevel [2345]
stop on runlevel [!2345]

respawn

exec uwsgi --emperor /etc/uwsgi/vassals/ --master --uid www-data --gid www-data --logto /var/log/uwsgi/emperor.log

And this is my vassal, ie. mysite.ini

[uwsgi]
base = /home/paul/djprojs/mysite
chdir = %(base)
module = mysite.wsgi:application
pidfile = /tmp/uwsgi_vassal_%n.pid
socket = /tmp/sockets/%n.sock
vacuum = True
wsgi-file = /home/paul/djprojs/mysite/mysite/wsgi.py
home = /home/paul/.virtualenvs/dj

Still working on how to clean it up but it is working like a beaut.

Best Answer

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Nginx + uWSGI on localhost *always* gives 502 Bad Gateway. Any ideas how to solve this

Ubuntu – Why is Upstart not starting uWSGI

Related Topic

Nginx + uWSGI on localhost always gives 502 Bad Gateway. Any ideas how to solve this