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

`

user www-data;

worker_processes auto;

error_log /var/log/nginx/error.log notice; pid /var/run/nginx.pid;

events { worker_connections 1024; }

http { include /etc/nginx/mime.types; default_type application/octet-stream;

log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';

access_log  /var/log/nginx/access.log  main;

sendfile        on;
#tcp_nopush     on;

keepalive_timeout  65;

#gzip  on;

upstream djangoapp {
    server app:8020;
}

server {
    listen 80;
    listen [::]:80;
    server_name demo.example.com;

    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl;
    listen [::]:443 ssl;

    server_name demo.example.com;

    ssl_certificate /etc/letsencrypt/live/demo.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/demo.example.com/privkey.pem;
    #ssl_protocols TLSv1.2 TLSv1.3;
    #ssl_prefer_server_ciphers on;

    location / {
        proxy_pass http://djangoapp;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        #proxy_set_header Upgrade $http_upgrade;
        #proxy_set_header Connection keep-alive;
        proxy_redirect off;
    }

    location /static/ {
        autoindex on;
        alias /static/;
    }
}

}

`

  • 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.

  • @lal309OP
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    11 year ago

    Yea not sure why it didn’t just crash and hid behind all kinds of successful messages.

    Fair enough! If I create a secondary config as you are suggesting, wouldn’t it create a conflict with the server blocks of default.conf? If I remember correctly, default.conf has a server listen 80 block going to localhost (which in my case wouldn’t be the correct path since the app is in another container) so wouldn’t nginx get confused because it doesn’t know which block to follow???

    Or maybe I saw the block in default.conf but it was all commented it out out of the box. Idk I had to step away for a sec. As you can imagine I’ve been bashing my head for hours and it turned out to be some bs I should have probably read the entire log stream. So I’m pretty angry/decompressing at the moment.

    • @chaospatterns
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      English
      11 year ago

      If I create a secondary config as you are suggesting, wouldn’t it create a conflict with the server blocks of default.conf

      No, you can have multiple server blocks with the same listen directive. They just need to differ by their server_name and only one server block can contain default_server; Reference

      NGINX will use the server_name directives to differentiate the different backend services. This is a class virtual host configuration model.

      • @lal309OP
        link
        English
        11 year ago

        Alright I’ll give it a try and see what happens. Thanks for your help!