Supervisor: ERROR (spawn error) when trying to launch gunicorn

Question

I have been trying to setup gunicorn with supervisor per these instructions. However when I run

sudo supervisorctl reread
sudo supervisorctl update
sudo supervisorctl start Server-CardLearning

I get the error Server-CardLearning: ERROR (spawn error).

My configuration file is simple.

[program:Server-CardLearning]
command = gunicorn app:app -b localhost:8000
directory = /home/alexg/www/<flask project>
user = www-data

I get the following errors in my log file.

...
...
2017-11-30 13:48:52,276 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
2017-11-30 13:49:10,595 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
2017-11-30 13:49:11,597 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
2017-11-30 13:49:13,599 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
2017-11-30 13:49:16,603 INFO spawnerr: unknown error making dispatchers for 'Server-CardLearning': ENOENT
2017-11-30 13:49:16,603 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
2017-11-30 13:58:12,101 INFO spawned: 'Server-CardLearning' with pid 13725
2017-11-30 13:58:12,560 INFO exited: Server-CardLearning (exit status 3; not expected)
2017-11-30 13:58:13,563 INFO spawned: 'Server-CardLearning' with pid 13730
2017-11-30 13:58:13,982 INFO exited: Server-CardLearning (exit status 3; not expected)
2017-11-30 13:58:15,986 INFO spawned: 'Server-CardLearning' with pid 13735
2017-11-30 13:58:16,411 INFO exited: Server-CardLearning (exit status 3; not expected)
2017-11-30 13:58:19,416 INFO spawned: 'Server-CardLearning' with pid 13742
2017-11-30 13:58:19,842 INFO exited: Server-CardLearning (exit status 3; not expected)
2017-11-30 13:58:20,843 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly
...
...
2017-11-30 14:10:29,728 INFO spawned: 'Server-CardLearning' with pid 13901
2017-11-30 14:10:29,957 INFO exited: Server-CardLearning (exit status 2; not expected)
2017-11-30 14:10:30,961 INFO spawned: 'Server-CardLearning' with pid 13902
2017-11-30 14:10:31,193 INFO exited: Server-CardLearning (exit status 2; not expected)
2017-11-30 14:10:33,200 INFO spawned: 'Server-CardLearning' with pid 13903
2017-11-30 14:10:33,436 INFO exited: Server-CardLearning (exit status 2; not expected)
2017-11-30 14:10:36,443 INFO spawned: 'Server-CardLearning' with pid 13904
2017-11-30 14:10:36,681 INFO exited: Server-CardLearning (exit status 2; not expected)
2017-11-30 14:10:37,682 INFO gave up: Server-CardLearning entered FATAL state, too many start retries too quickly

Where am I going wrong? I have tried some things I saw on stack overflow, but nothing proved to be relevant to this problem.

Answer 1

The root of the problem seemed to be that I had an issue with app.py. I was using some Flask library that I had installed on my local machine but not the server and for some reason I didn't get big errors when I ran the server via flask run --host=0.0.0.0.

I figured this out by adjusting supervisor .conf file which is located at /etc/supervisor/conf.d/Server-CardLearning.conf

The new .conf file reads:

[program:Server-CardLearning]
environment=SECRET_KEY="some_secret_key"
command=gunicorn app:app -b localhost:8000
directory=/home/alexg/www/Server-CardLearning
user=alexg
autostart=true
stderr_logfile=/var/log/supervisor/test.err.log
stdout_logfile=/var/log/supervisor/test.out.log

By adding the two log files I was able to run:

cat /var/log/supervisor/test.err.log

to see that I had an uninstalled library! ~Gasp!~

After installing the library, I ran:

sudo supervisorctl reread
sudo supervisorctl update
sudo supervisorctl start Server-CardLearning

Now, if that doesn't fix it, I also found that digging around in the supervisor console was helpful:

$ sudo supervisorctl
supervisor> help
supervisor> status

I hope this helps someone out!

Answer 2

In my case accidentally i removed the logs folder where the supervisor logs was pointing to so creating those folder and restarting the supervisor did the trick.

Sample supervisor.conf

[program:Server-CardLearning]
environment=SECRET_KEY="some_secret_key"
command=gunicorn app:app -b localhost:8000
directory=/home/alexg/www/Server-CardLearning
user=alexg
autostart=true
stderr_logfile=/var/log/supervisor/test.err.log
stdout_logfile=/var/log/supervisor/test.out.log

So all i did was :-

mkdir /var/log/supervisor/

after that :-

sudo supervisorctl status all