This is great! But.... it's not quite done yet! This fixes #7671 (yay!). But check out the comment in that issue. In 3.3, setTrustedProxies() has a required second argument: https://github.com/symfony/symfony/blob/fb532bfc172a531bce4219e4f21db124eb972bbc/src/Symfony/Component/HttpFoundation/Request.php#L591-L594

We need to update the example to pass this value, and mention what it is.

@JarJak do you think you could make that change?

Sorry, but actually I am not sure how to describe this "header" option because I've never used it :(

I think that this PR should also be the one fixing #7045
by telling about Request::HEADER_X_FORWARDED_AWS_ELB

I just chatted with Nicolas about this! There are a few situations:

A) On AWS behind an ELB

Request::setTrustedProxies([...], Request::HEADER_X_FORWARDED_AWS_ELB);

B) On most other systems (systems where your proxy passes X-FORWARDED-* headers:

Request::setTrustedProxies([...], Request::HEADER_X_FORWARDED_ALL);

C) If your load balancer passes the "Forwarded" header from rfc 7239, then use:

Request::setTrustedProxies([...], Request::HEADER_FORWARDED);

For the IP address - the [...] part, this is still the same IP address or IP range of your proxy as before. And as before if your IP constantly changes (like on ELB), you should still use $request->server->get('REMOTE_ADDR') (assuming public traffic cannot hit your server directly). In other words, this note is still valid: http://symfony.com/doc/current/request/load_balancer_reverse_proxy.html#but-what-if-the-ip-of-my-reverse-proxy-changes-constantly (it just needs to be updated to have a 2nd argument).

@JarJak Would you care to update your PR given this new info? I also had problems understanding it at first :)

Hey @JarJak! I've just finished this PR in #7952 - just because this is an important change and the release is upon us! But, your commits are in that PR - so you are a Symfony Docs contributor :).

Thanks!