Nginx reverse proxy to .Net Core API in docker - docker

Question

I'm having trouble trying to get the following to work in Docker
What I want is that when the user requests http://localhost/api then NGINX reverse proxies to my .Net Core API running in another container.
Container Host: Windows
Container 1: NGINX
dockerfile
FROM nginx
COPY ./nginx.conf /etc/nginx/nginx.conf
nginx.conf
user nginx;
worker_processes 1;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
server {
location /api1 {
proxy_pass http://api;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection keep-alive;
proxy_set_header Host $host;
proxy_cache_bypass $http_upgrade;
}
}
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$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;
include /etc/nginx/conf.d/*.conf;
}
Container 2: .Net Core API
Dead simple - API exposed on port 80 in the container
Then there is the docker-compose.yml
docker-compose.yml
version: '3'
services:
api1:
image: api1
build:
context: ./Api1
dockerfile: Dockerfile
ports:
- "5010:80"
nginx:
image: vc-nginx
build:
context: ./infra/nginx
dockerfile: Dockerfile
ports:
- "5000:80"
Reading the Docker documentation it states:
Links allow you to define extra aliases by which a service is
reachable from another service. They are not required to enable
services to communicate - by default, any service can reach any other
service at that service’s name.
So as my API service is called api1, I've simply referenced this in the nginx.conf file as part of the reverse proxy configuration:
proxy_pass http://api1;
Something is wrong as when I enter http:\\localhost\api I get a 404 error.
Is there a way to fix this?

Answer 1

The problem is the nginx location configuration.
The 404 error is right, because your configuration is proxying request from http://localhost/api/some-resource to a missing resource, because your mapping is for /api1 path and you're asking for /api.
So you should only change the location to /api and it will work.
Keep in mind that requests to http://localhost/api will be proxied to http://api1/api (the path is kept). If your backend is configured to expose api with a prefixing path this is ok, otherwise you will receive another 404 (this time from your service).
To avoid this you should rewrite the path before proxying the request with a rule like this:
# transform /api/some-resource/1 to /some-resource/1
rewrite /api/(.*) /$1 break;