Nginx Reverse Proxy cannot communicate with container - docker

Question

I've been trying to teach myself Nginx. Naturally I figured I should use docker. I'm trying to do this with docker for windows. Would eventually move to Linux server. I feel like I'm so close, but I'm stuck on this last issue.
reverseproxy_1 | 2021/07/14 22:37:31 [error] 31#31: *1 connect() failed (111: Connection refused) while connecting to upstream, client: 172.18.0.1, server: , request: "GET /favicon.ico HTTP/1.1", upstream: "http://172.18.0.2:5000/favicon.ico", host: "localhost:4000", referrer: "http://localhost:4000/"
Anyone have any suggestions? I'm new to this, so it's probably something stupid. I've gone through several tutorials and I really feel like this should work.
version: '3.7'
services:
web:
image: 'anatomy-lab2'
container_name: 'AnatomyLabWeb'
ports:
- "5000:80"
restart: always
reverseproxy:
image: nginx:alpine
volumes:
- ./nginx.conf:/etc/nginx/nginx.conf:ro
ports:
- '4000:4000'
depends_on:
- web
restart: always
user nginx;
events {
worker_connections 1000;
}
http {
upstream web-api {
server web:5000;
}
server {
listen 4000;
location / {
proxy_pass http://web-api;
}
}
}
λ docker-compose up
Starting AnatomyLabWeb ... done
Starting anatomy-lab_reverseproxy_1 ... done
Attaching to AnatomyLabWeb, anatomy-lab_reverseproxy_1
reverseproxy_1 | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
reverseproxy_1 | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
reverseproxy_1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
reverseproxy_1 | 10-listen-on-ipv6-by-default.sh: info: IPv6 listen already enabled
reverseproxy_1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
reverseproxy_1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
reverseproxy_1 | /docker-entrypoint.sh: Configuration complete; ready for start up
AnatomyLabWeb | [04:56:26 WRN] Storing keys in a directory '/root/.aspnet/DataProtection-Keys' that may not be persisted outside of the container. Protected data will be unavailable when container is destroyed
.
AnatomyLabWeb | [04:56:26 INF] User profile is available. Using '/root/.aspnet/DataProtection-Keys' as key repository; keys will not be encrypted at rest.
AnatomyLabWeb | Hosting environment: Production
AnatomyLabWeb | Content root path: /app
AnatomyLabWeb | Now listening on: http://[::]:80
AnatomyLabWeb | Application started. Press Ctrl+C to shut down.
reverseproxy_1 | 2021/07/15 04:56:33 [error] 23#23: *1 connect() failed (111: Connection refused) while connecting to upstream, client: 172.18.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://172.18.
0.2:5000/", host: "localhost:4000"
reverseproxy_1 | 172.18.0.1 - - [15/Jul/2021:04:56:33 +0000] "GET / HTTP/1.1" 502 559 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36"
reverseproxy_1 | 2021/07/15 04:56:33 [error] 23#23: *1 connect() failed (111: Connection refused) while connecting to upstream, client: 172.18.0.1, server: , request: "GET /favicon.ico HTTP/1.1", upstream: "htt
p://172.18.0.2:5000/favicon.ico", host: "localhost:4000", referrer: "http://localhost:4000/"
reverseproxy_1 | 172.18.0.1 - - [15/Jul/2021:04:56:33 +0000] "GET /favicon.ico HTTP/1.1" 502 559 "http://localhost:4000/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome
/91.0.4472.124 Safari/537.36"
I get the web app to work just fine by itself (asp.net/kestrel). But I can't seem to hook it to Nginx.
Any thoughts on this would be great. I've been stuck for quite a bit of time.

Answer 1

The problem came from
upstream web-api {
server web:5000;
}
In the dockerized environment the web container listens :80 so you need to change the config like
upstream web-api {
server web:80;
}