Proxying an app that doesn't want to be proxied

README.md

There's an app running at app.test.example.com that I want to make changes to, but I don't want to go through the hassle of getting the source code and getting it set up on my machine. Not when I can fake it with nginx much quicker!

app.test.example.com depends on a service svc.test.example.com. The main JS looks for the environment in the page URL; if I run locally at app.local.example.com it will declare the environment to be "local" and look for a service at svc.local.example.com.

I just have to make sure the service sees what it wants to see: a Host of svc.test.example.com and an Origin of http://app.test.example.com. I also need to keep the browser happy by blocking the Access-Control-Allow-Origin value the service is passing down and using my local one instead.

Works like a charm! Now I can use a try_files directive to selectively replace JS files from the app, and fetch them from the proxied app if they don't exist locally.

hosts

# add to the end of /etc/hosts
127.0.0.1 app.test.example.com svc.test.example.com

nginx.conf

    server {
      listen 80;
      server_name app.local.example.com;

      location / {
        proxy_pass http://app.test.example.com;
        proxy_set_header Host app.test.example.com;
      }
    }

    server {
      listen 80;
      server_name svc.local.example.com;

      location / {
        proxy_pass http://svc.test.example.com;
        proxy_hide_header Access-Control-Allow-Origin;
        proxy_set_header Host svc.test.example.com;
        proxy_set_header Origin http://app.test.example.com;
        proxy_set_header Referer http://app.test.example.com;
        add_header Access-Control-Allow-Origin http://app.local.example.com;
      }
    }