Update
The details in this question are getting long, but I think it narrows down to this:
For some reason the host name matters to Nginx when it's trying to figure out whether to proxy the request. If the host name is set to git.example.com the request does not seem to go through, but if it's set to 203.0.113.2 then it goes through. Why does the host name matter?
Filed an issue with Nginx here And docker compose
Start of original question
When I type in the IP address of the reverse proxy directly into my browser bar, it does perform the redirect.
When using a URL that is resolved via the /etc/hosts entry 203.0.113.2 git.example.com the "Welcome to Ngnix page" is shown. Any ideas? This is the configuration:
server {
listen 203.0.113.2:80 default_server;
server_name 203.0.113.2 git.example.com;
proxy_set_header X-Real-IP $remote_addr; # pass on real client IP
location / {
proxy_pass http://203.0.113.1:3000;
}
}
This is the docker-compose.yml file that is used to launch the whole thing:
version: '3'
services:
gogs-nginx:
build: ./proxy
ports:
- "80:80"
networks:
mk1net:
ipv4_address: 203.0.113.2
gogs:
image: gogs/gogs
ports:
- "3000:3000"
volumes:
- gogs-data:/data
networks:
mk1net:
ipv4_address: 203.0.113.3
volumes:
gogs-data:
external: true
networks:
mk1net:
ipam:
config:
- subnet: 203.0.113.0/24
One interesting thing is that I can navigate to for example:
http://203.0.113.2/issues
The log for the above URL is:
gogs-nginx_1 | 203.0.113.1 - - [07/Oct/2018:11:28:06 +0000] "GET / HTTP/1.1" 200 38825 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36" "-"
If I then change 203.0.113.2 with git.example.com (So that the url ends up being git.example.com I get Nginxs "404 not found" page, and the log says:
gogs-nginx_1 | 2018/10/07 11:31:34 [error] 8#8: *10 open() "/usr/share/nginx/html/issues" failed (2: No such file or directory), client: 203.0.113.1, server: localhost, request: "GET /issues HTTP/1.1", host: "git.example.com"
If I only use http://git.example.com as the URL I get the NGINX welcome page, and the following log:
gogs-nginx_1 | 203.0.113.1 - - [07/Oct/2018:11:34:39 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36" "-"
It looks like Nginx understands that the request is for the proxy because it logs the IP of the proxy, but it does not redirect to the proxy and returns a 304 ...
Using Curl to perform requests
Using curl with a host name parameter that targets the proxy like this:
curl -H 'Host: git.example.com' -si http://203.0.113.2
Results in the Nginx welcome page:
ole@mki:~/Gogs/.gogs/docker$ curl -H 'Host: git.example.com' -si http://203.0.113.2
HTTP/1.1 200 OK
Server: nginx/1.15.1
Date: Sun, 07 Oct 2018 17:09:11 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 03 Jul 2018 13:27:08 GMT
Connection: keep-alive
ETag: "5b3b79ac-264"
Accept-Ranges: bytes
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
But if I change the host name to the ip address like this:
Using curl with a host name parameter that targets the proxy like this:
curl -H 'Host: 203.0.113.2' -si http://203.0.113.2
Then the proxy works as it should:
ole@mki:~/Gogs/.gogs/docker$ curl -H 'Host: 203.0.113.2' -si http://203.0.113.2
HTTP/1.1 302 Found
Server: nginx/1.15.1
Date: Sun, 07 Oct 2018 17:14:46 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 34
Connection: keep-alive
Location: /user/login
Set-Cookie: lang=en-US; Path=/; Max-Age=2147483647
Set-Cookie: i_like_gogits=845bb09d69587b81; Path=/; HttpOnly
Set-Cookie: _csrf=neGgBfG4LdOcdrdeA0snHjVGz4s6MTUzODkzMjQ4NjE5MzEzNzI3OQ%3D%3D; Path=/; Expires=Mon, 08 Oct 2018 17:14:46 GMT; HttpOnly
Set-Cookie: redirect_to=%252F; Path=/
<a href="/user/login">Found</a>.
