Merge ~troyanov/maas:proxy-headers-backport-3.2 into maas:3.2

[Anton Troyanov]

fix(region): use $http_host to read Host header

$http_name
arbitrary request header field;

the last part of a variable name is the field name converted to lower case
with dashes replaced by underscores

Resolves LP:2009186

(cherry picked from commit eff39899eab1331f712aa8c4f9f2004f9aded683)

[Anton Troyanov (troyanov)]

Self approve backport to 3.2

review: Approve

[MAAS Lander (maas-lander)]

UNIT TESTS
-b proxy-headers-backport-3.2 lp:~troyanov/maas/+git/maas into -b 3.2 lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: c68f66037258aa4f6b8147b1f2343d49bd77cd23

review: Approve

diff --git a/src/maasserver/templates/http/regiond.nginx.conf.template b/src/maasserver/templates/http/regiond.nginx.conf.template
index 22ad4ee..f34ac01 100644
--- a/src/maasserver/templates/http/regiond.nginx.conf.template
+++ b/src/maasserver/templates/http/regiond.nginx.conf.template
@@ -11,7 +11,7 @@ proxy_set_header Host $host;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 proxy_set_header X-Forwarded-Proto $scheme;
-proxy_set_header X-Forwarded-Host $host:$server_port;
+proxy_set_header X-Forwarded-Host $http_host;
 
 server {
     {{if tls_enabled}}