Heads up! Long post and lots of head bashing against the wall.
Context:
I have a written an a python app (Django). I have dockerized the deployment and the compose file has three containers, app, nginx and postgres. I'm currently trying to deploy a demo of it in a VPS running Debian 11. Information below has been redacted (IPs, Domain name, etc.)
Problem:
I keep running into 502 errors. Locally things work very well even with nginx (but running on 80). As I try to deploy this I'm trying to configure nginx the best I can and redirecting http traffic to https and ssl certs. The nginx logs simply say "connect() failed (111: Connection refused) while connecting to upstream, client: 1.2.3.4, server: demo.example.com, request: "GET / HTTP/1.1", upstream: "http://192.168.0.2:8020/", host: "demo.example.com"". I have tried just about everything.
What I've tried:
Adding my server block configs to /etc/nginx/conf.d/default.conf
Adding my server block configs to a new file in /etc/nginx/conf.d/app.conf and leaving default at out of box config.
Tried putting the above config (default.conf and app.conf) in sites-available (/etc/nginx/sites-available/* not at the same time tho).
Recreated /etc/nginx/nginx.conf by copy/pasting out of box nginx.conf and then adding server blocks directly in nginx.conf
Running nginx -t inside of the nginx container (Syntax and config were "successful")
Running nginx -T when recreated /etc/nginx/nginx.conf
nginx -T when the server blocks where in /etc/nginx/conf.d/* lead me to think that since there were two server listen 80 blocks that I should ensure only one listen 80 block was being read by the container hence the recreated /etc/nginx/nginx.conf from above
Restarted container each time a change was made.
Changed the user block from nginx (no dice when using nginx as user) to www-data, root and nobody
Deleted my entire docker data and redeployed everything a few times.
Double checked the upstream block 1,000 times
Confirmed upstream block container is running and on the right exposed port
Checked access.log and error.log but they were both empty (not sure why, tried cat and tail)
Probably forgetting more stuff (6 hours deep in the same error loop by now)
How can you help:
Please take a look at the nginx.conf config below and see if you guys can spot a problem, PLEASE! This is my current /etc/nginx/nginx.conf
EDIT: I have also confirmed that both containers are connected to the same docker network (docker network inspect frontend)
EDIT 2: Solved my problem. See my comments to @chaospatterns. TLDR there was an uncaught exception in the app but it didn’t cause a crash with the container. Had to dig deep into logs to find it.
While not directly solving the problem, my usual setup involves installing webmin with nginx and managing my domains and nginx from there, changing the auto-generated domain configs to proxy to docker. I have yet to find an easier solution.
My biggest gripe with it is that it sets up a few things I don't need, like PHP, disk quotas, etc.