I try to set up a docker-compose environment in which a Nginx container receives HTTPS requests, handles the SSL and reverse proxies them to a dotnet-core app which only implements HTTP.

This topic has been discussed here several times and I tried to create a minimal configuration that just serves this purpose ( Similar to this: NGINX SSL Pass-thru and Docker )

The problem is, that Nginx reponds with a 404 despite being configured to proxy_pass requests to the dotnet-core app which currently simply respons 'Hello world' to all requests.

nginx_1     | 2021/06/25 04:07:54 [error] 24#24: *1 "/etc/nginx/html/index.html" is not found (2: No such file or directory), client: 210.61.91.199, server: tgdev.pillepalle1.de, request: "GET / HTTP/1.1", host: "tgdev.pillepalle1.de"

I connected with the container and extracted the setup from there

root@70e20feb4fae:/etc/nginx# ls -l

total 32
drwxr-xr-x 1 root root 4096 Jun 25 01:49 conf.d
-rw-r--r-- 1 root root 1007 May 25 12:28 fastcgi_params
-rw-r--r-- 1 root root 5290 May 25 12:28 mime.types
lrwxrwxrwx 1 root root   22 May 25 13:01 modules -> /usr/lib/nginx/modules
-rw-r--r-- 1 root root  648 May 25 13:01 nginx.conf
-rw-r--r-- 1 root root  636 May 25 12:28 scgi_params
-rw-r--r-- 1 root root  664 May 25 12:28 uwsgi_params

root@70e20feb4fae:/etc/nginx# cat nginx.conf

user  nginx;
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;

    include /etc/nginx/conf.d/*.conf;
}

root@70e20feb4fae:/etc/nginx/conf.d# ls

certbot.conf  default.conf

root@70e20feb4fae:/etc/nginx/conf.d# cat default.conf

server {
    listen       80;
    listen  [::]:80;
    server_name  localhost;

    location / {
        # return 301 https://$host/$request_uri;
        proxy_pass http://tgwebapp:80;
    }
}

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

    server_name  localhost;

    ssl_certificate /etc/letsencrypt/live/this/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/this/privkey.pem;

    location / {
        proxy_pass http://tgwebapp:80;
    }
}

root@70e20feb4fae:/etc/nginx/conf.d# cat certbot.conf

server {
    listen       80;
    listen  [::]:80;
    server_name  localhost;

    location /.well-known/ {
        proxy_pass http://certbot;
    }
}

There is no entry that should nginx cause to serve /etc/nginx/html/index.html. What am I missing?