Before this change, the Pre-Flight URL check would inevitably fail
whenever Snipe-IT was running behind a reverse proxy or load balancer.
The URL check tries to ensure that the configured application URL
matches the URL that is actually used to reach the application. However,
when running behind an HTTP intermediary (like a reverse proxy or a load
balancer) the HTTP connection that Snipe-IT receives is not the _real_
connection from the user anymore, but a connection from the HTTP
intermediary. The scheme, host and port that Snipe-IT would obtain from
that incoming intermediary connection wouldn't match what is configured
as application URL and, therefore, the URL check would fail.
This commit solves the situation by making Snipe-IT's Pre-Flight URL
check aware of the `X-Forwarded-Proto` and `X-Forwarded-Host` HTTP
headers. These headers represent the _de-facto_ standard used by reverse
proxies and other HTTP intermediary components to convey information
about the incoming HTTP connection to the upstream application. Being
the upstream application, Snipe-IT can then make use of this information
to correctly evaluate the validity of the configured application URL.
So that the message displayed to the user when the URL Pre-Flight check
fails is:
> Snipe-IT thinks your URL is SCHEME://DOMAIN, but your real
URL is SCHEME://DOMAIN/setup
instead of:
> Snipe-IT thinks your URL is SCHEME://DOMAIN/setup, but your real
URL is SCHEME://DOMAIN/setup
Having a missing "/setup" in the expected URL might confuse the user
into thinking that it is an additional configuration problem they need
to fix.
With this change, the comparison between the expected and actual URL
will not contain any accidental difference anymore. Only those that the
user really needs to be aware of and fix in their setup.
WIP: Wiring up more and more of the actions on the importer
Files now upload okay, a little glitchy on the display-side though
add to readmes so i dont forget
