uWSGI configuration with FlaskApp - flask

Question

In effort to switch to Nginx, I'm running into configuration problems and getting a 502 Gateway error. Here is error log on connection:
tail -f error.log
2016/10/08 16:09:31 [crit] 21682#21682: *29 connect() to unix:/var/www/FlaskApp/FlaskApp/runserver.sock failed (13: Permission denied) while connecting to upstream, client: 73.188.249.47, server: ceejcalvert.com, request: "GET / HTTP/1.1", upstream: "uwsgi://unix:/var/www/FlaskApp/FlaskApp/runserver.sock:", host: "website.com"
If I'm in the terminal on the server I can get the site up by manually directing the socket via:
This command will get everything working if run:
uwsgi -s /var/www/FlaskApp/FlaskApp/runserver.sock -w runserver:app --chmod-socket=666
The issue is I cannot get it working in daemon mode. My configuration is as follows:
$ cat /etc/systemd/system/runserver.service
[Unit]
Description=uWSGI instance to serve runserver
After=network.target
[Service]
User=username
Group=www-data
WorkingDirectory=/var/www/FlaskApp/FlaskApp
Environment="PATH=/var/www/FlaskApp/FlaskApp/venv/bin"
ExecStart=/var/www/FlaskApp/FlaskApp/venv/bin/runserver.sock --ini runserver.ini
[Install]
WantedBy=multi-user.target
...
cat /var/www/FlaskApp/FlaskApp/runserver.ini
[uwsgi]
module = wsgi:app
master = true
processes = 5
logto = /home/jmc856/error.log
socket = runserver.sock
chmod-socket = 666
vacuum = true
die-on-term = true
Assume site-available is linked to sites-enabled
cat /etc/nginx/sites-available/runserver
server {
listen 80;
server_name website.com;
location / {
include uwsgi_params;
uwsgi_pass unix:/var/www/FlaskApp/FlaskApp/runserver.sock;
}
}
Anything obvious I'm missing?
When I run the following, I get exit code 3.
sudo systemctl status runserver
runserver.service - uWSGI instance to serve runserver
Loaded: loaded (/etc/systemd/system/runserver.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Sat 2016-10-08 16:08:45 EDT; 20min ago
Main PID: 22365 (code=exited, status=203/EXEC)
Oct 08 16:08:45 FirstNameLastName.com systemd[1]: Stopped uWSGI instance to serve runserver.
Oct 08 16:08:45 FirstNameLastName.com systemd[1]: Started uWSGI instance to serve runserver.
Oct 08 16:08:45 FirstNameLastName.com systemd[1]: runserver.service: Main process exited, code=exited, status=203/EXEC
Oct 08 16:08:45 FirstNameLastName.com systemd[1]: runserver.service: Unit entered failed state.
Oct 08 16:08:45 FirstNameLastName.com systemd[1]: runserver.service: Failed with result 'exit-code'.

Answer 1

Solved my issue. For the most part my configurations were fine. Here is a checklist of things to ensure if you get 502 gateway errors.
1) I first added all absolute paths to config files. For example I changed my systemd config to:
$ cat /etc/systemd/system/runserver.service
[Unit]
Description=uWSGI instance to serve runserver
After=network.target
[Service]
User=username
Group=www-data
WorkingDirectory=/var/www/FlaskApp/FlaskApp
Environment="PATH=/var/www/FlaskApp/FlaskApp/venv/bin"
ExecStart=/var/www/FlaskApp/FlaskApp/venv/bin/runserver.sock --ini /var/www/FlaskApp/FlaskApp/runserver.ini
[Install]
WantedBy=multi-user.target
2) Changed .ini file to directly call uWSGI app:
cat /var/www/FlaskApp/FlaskApp/runserver.ini
[uwsgi]
chdir=/var/Webpage/
wsgi-file = wsgi.py
callable = app
master = true
processes = 5
logto = /home/error.log
socket = runserver.sock
chmod-socket = 666
vacuum = true
die-on-term = true
3) Ensure FlaskApp host is 0.0.0.0:
if __name__ == "__main__":
app.run(host='0.0.0.0')
4) Use these commands to try to find out where things are failing.
Make sure configs have proper syntax
$ sudo nginx -t
Make sure nginx daemon running properly
$ systemctl status nginx.service
Ensure uWSGI instance to serve {app} is running.
$ systemctl
If all is good and still finding errors, search for failure in
$ sudo journalctl
And
$ sudo tail -f /var/log/nginx/error.log
If everything is running properly, make sure you perform the following:
$ sudo systemctl restart {app}
$ sudo start {app}
$ sudo enable {app}
That last command was something I forgot and prevented me from realizing my configuration was fine for a long time. In my case {app} was 'runserver'

Answer 2

I've been using this Docker image for all my nginx and flask apps
https://github.com/tiangolo/uwsgi-nginx-flask-docker