nginx proxy_pass url with GET params conditionally

Question

I have a url http://foo.com/banana and I have another url http://foo.com/banana?a=1&b=2

I like that all /banana routes are handled by my local nginx, but I'd like any banana routes with GET params to be proxied to http://bar.com

so:

http://foo.com/banana -> http://foo.com/banana

http://foo.com/banana?a=1 -> (proxy) -> http://bar.com/banana?a=1

I should note this is not for production. I'm trying to redirect api calls to redirect to another server during development.

I've tried to do an 'if args' block but I can't do a proxy_pass in an if block. I thought about doing a rewrite of: http://foo.com/banana?a=1 -> http://foo.com/proxy?a=1

location /proxy {
   proxy_pass http://bar.com;
}

But I don't have the right logic for above because bar.com is expecting the /banana route.

Any ideas?

Answer 1

Since this is not for production, you could stick with your original "if" solution. You only need to escape from the "if" block to be able to proxy_pass, which can be easily done with the traditional trick:

location /banana {
    error_page 418 = @good_old_fallback;

    if ($args) {
        return 418;
    }
}

location @good_old_fallback {
    proxy_pass http://bar.com;
}

Your idea of using another location will also work, so if you prefer it better, you can go with something like this:

location /banana {
    if ($args) {
        rewrite ^/banana(.*)$ /proxy$1 last;
    }
}

location /proxy {
    internal;
    rewrite ^/proxy(.*)$ /banana$1 break;
    proxy_pass http://bar.com;
}