Thursday, 19 September, 2019 UTC
Summary
Instead of upgrading everything on my server, I'm just starting from scratch. From Ubuntu 16.04 to Ubuntu 19.04 and I also upgraded everything else in sight. One of them was
uwsgi. I copied various user config files but for uwsgi things didn't very well. On the old server I had uwsgi version 2.0.12-debian and on the new one 2.0.18-debian. The uWSGI changelog is pretty hard to read but I sure don't see any mention of this.You see, on SongSearch I have it so that Nginx talks to Django via a uWSGI socket. But the NodeJS server talks to Django via
127.0.0.1:PORT. So I need my uWSGI config to start both. Here was the old config:[uwsgi] plugins = python35 virtualenv = /var/lib/django/songsearch/venv pythonpath = /var/lib/django/songsearch user = django uid = django master = true processes = 3 enable-threads = true touch-reload = /var/lib/django/songsearch/uwsgi-reload.touch http = 127.0.0.1:9090 module = songsearch.wsgi:application env = LANG=en_US.utf8 env = LC_ALL=en_US.UTF-8 env = LC_LANG=en_US.UTF-8
(The only difference on the new server was the
python37 plugin instead)I start it and everything looks fine. No errors in the log files. And
netstat looks like this:# netstat -ntpl | grep 9090 tcp 0 0 127.0.0.1:9090 0.0.0.0:* LISTEN 1855/uwsgi
But every time I try to
curl localhost:9090 I kept getting curl: (52) Empty reply from server. Nothing in the log files! It seemed no matter what I tried I just couldn't talk to it over HTTP. No, I'm not a sysadmin. I'm just a hobbyist trying to stand up my little server with the tools and limited techniques I know but I was stumped.The solution
After endless Googling for a resolution and trying all sorts of
uwsgi commands directly, I somehow stumbled on the solution.[uwsgi] plugins = python35 virtualenv = /var/lib/django/songsearch/venv pythonpath = /var/lib/django/songsearch user = django uid = django master = true processes = 3 enable-threads = true touch-reload = /var/lib/django/songsearch/uwsgi-reload.touch -http = 127.0.0.1:9090 +http-socket = 127.0.0.1:9090 module = songsearch.wsgi:application env = LANG=en_US.utf8 env = LC_ALL=en_US.UTF-8 env = LC_LANG=en_US.UTF-8
With this one subtle change, I can now
curl localhost:9090 and I still have the /var/run/uwsgi/app/songsearch/socket socket. So, yay!I'm blogging about this in case someone else ever gets stuck in the same nasty surprise as me.
Also, I have to admit, I was fuming with rage from this frustration. It's really inspired me to revive the quest for an alternative to
uwsgi because I'm not sure it's that great anymore. There are new alternatives such as gunicorn, gunicorn with Meinheld, bjoern etc.