Redirect traffic based on url to different ip address maintaining port and url information [duplicate]

Question

We have a QA version, a UAT version, and a DEV version of webapp. Users need to access these via http://uat.company.com:41002/webapp, http://qa.company.com:41002/webapp, and http://dev.company.com:41002/webapp. There is also a different webapp on port 41001 and also on port 8080 they will need to access.

These url's are required to be available externally to the company, and we only have one public ip address they can be accessed on. As such DNS records need all 3 address to point to one IP. On that single IP address, a server resides running nginx. in the background I need for each url to point to a different server

http://uat.company.com --> 123.123.123.1
http://qa.company.com  --> 123.123.123.2
http://dev.company.com --> 123.123.123.3

I'm afraid I don't know the correct terminology, however the remainder of the URI and the port must also be carried over to the ip address. I.e. if someone visits

http://uat.company.com:41002/webapp/somepage`

it will appear as though that is the page they have visited, but really they will be looking at

http://123.123.123.1:41002/webapp/somepage

or if they visited

http://qa.company.com:8080/static/home.html

they would really be looking at

http://123.123.123.2:8080/static/home.html

but their browser would still say http://qa.company.com:8080/static/home.html

I have tried

server {

    server_name uat.company.com;

    listen 41001;
    listen 41002;
    listen 8080;

    location / {
            proxy_pass http://123.123.123.1:$server_port$uri;
            proxy_set_header Host $host;
    }

}

however this gives me a bad gateway 502 page with log: 2015/01/28 16:04:49 [crit] 30571#0: *1 connect() to 123.123.123.1:41002 failed (13: Permission denied) while connecting to upstream, client: 172.23.128.245, server: uat.company.com, request: "GET /webapp/ HTTP/1.1", upstream: "http://123.123.123.1:41002/webapp/", host: "uat.company.com:41002"

I hope this is more clear.

---

Update From Xaviers suggestion that SELinux might have been hampering, I have disabled it and I do get further. Using the nginx config above now seems to be connecting to the second server: The port however is still not carried through. I am calling

uat.company.com:41002/webapp/

This would, if calling the service directly, redirect to

uat.company.com:41002/webapp/spring/config/main

However what is happening through the proxy is that it is returning or ending up at

uat.company.com/webapp/spring/config/main

and thus failing to load a page...

Answer 1

I have established what the problems were with my setup.

1) SELinux was preventing me from connecting upstream. I have now disabled this and will consider setting it up properly later

2) proxy_pass was doing its job as expected, however the args I needed were http://123.123.123.1:$server_port/$uri$is_args$args;

3) proxy_set_header Host $host correctly set the hostname back to what I wanted, however it ate the port number. The correct format for my needs is proxy_set_header Host $host:$server_port

There may be neater solutions to this, and I haven't got a full working solution yet as I have cut it down to get it working, however a working section of my config is:

server {
    listen 41002;
    server_name uat.comapny.com;

    location /webapp {
        proxy_pass http://123.123.123.1:41002/$uri$is_args$args;
        proxy_set_header Host $host:$server_port;
    }
}

I will post a more generic version once I have fleshed it out. Many thanks to all who helped.

Answer 2

You want to maintain the port, then you should put it in proxy_pass.

server {

    server_name bob.something.com;

    listen 41001;
    listen 41002;
    listen 8080;

    location / {
            proxy_pass http://123.123.123.1:$server_port$uri;
            proxy_set_header Host $host;
    }
}

You have to realize that this will proxy request through nginx.