NGINX中的级联proxy_pass

Question

I'd like to do something like the following:

location ~ ^/(?<upstream>[^/]+)/ {
  rewrite /$upstream/(.*) /api/public/$1  break;

  if ($upstream = "auth") {
    proxy_pass ${AUTH_SERVICE};
  }
  if ($upstream = "todos") {
    proxy_pass ${TODO_SERVICE};
  }
  if ($upstream = "analysis") {
    proxy_pass ${ANALYSIS_SERVICE};
  }
  if ($upstream = "stuff") {
    proxy_pass ${STUFF_SERVICE};
  }
  if ($upstream = "users") {
    proxy_pass ${USERS_SERVICE};
  }
  return 404;
}

The proxy_pass values are built fine with envsubst .

As an example, requests to public-api.com/auth/* would be mapped to auth-service.com/api/public/* .

When I make the request curl http://localhost:8000/auth/ping , I get a 404, but I can hit auth-service.com/api/public/deep_ping directly.

Can anyone spot the bug in the implementation? Is something like this even advisable?

Answer 1

I assume the problem are the if statements. If an if matches, the rewrite rule will not be applied.

At least that is my understand after reading the If Is Evil article.

One alternative to deal with non-trivial logic is to use embedded scripting in Nginx. For instance, embedded perl or Lua (part of for OpenResty ). There is some overhead in setting it up, but as you are then using a normal programming language, implementing complex logic is easier as there are less surprises.

Answer 2

Thanks for the link Philipp. From reading it, I was able to understand how this works (and is safe):

location ~ /(?<api>[^/]+)/ {
  set $backend 0;

  if ($api = "auth") {
    set $backend ${AUTH_SERVICE};
  }
  if ($api = "todos") {
    set $backend ${TODO_SERVICE};
  }
  if ($api = "analysis") {
    set $backend ${ANALYSIS_SERVICE};
  }
  if ($api = "stuff") {
    set $backend ${STUFF_SERVICE};
  }
  if ($api = "users") {
    set $backend ${USERS_SERVICE};
  }

  if ($backend = 0) {
    return 404;
  }

  rewrite /([^/]+)/(.*) /$2 break;
  proxy_pass $backend;
}