Merge ~troyanov/maas:rackd-nginx-conf into maas:master

[Anton Troyanov]

fix: use original Host value when proxy_set_header

Resolves LP:2022926

In regiond we do have proxy_set_header X-Forwarded-Host $http_host; which is used by Django stuff to build absolute URL

$http_host that we use to fill it basically takes original Host header information
http://nginx.org/en/docs/http/ngx_http_proxy_module.html#var_proxy_host

So why this fix is needed:
Because if in rackd config we set Host header to $host, we are losing port information. That leads to regiond having Host header without port, leading to $http_host not having port and breaking metadata_url

[MAAS Lander (maas-lander)]

UNIT TESTS
-b rackd-nginx-conf lp:~troyanov/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: a4c11bd4133dbfe0356e45bf1c17b99f2b8bf5cc

review: Approve

[Alberto Donato (ack)]

+1

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b rackd-nginx-conf lp:~troyanov/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas-tester/3001/console

diff --git a/src/provisioningserver/templates/http/rackd.nginx.conf.template b/src/provisioningserver/templates/http/rackd.nginx.conf.template
index f73a7be..8ec9ae0 100644
--- a/src/provisioningserver/templates/http/rackd.nginx.conf.template
+++ b/src/provisioningserver/templates/http/rackd.nginx.conf.template
@@ -12,9 +12,9 @@ server {
 
     {{if upstream_http}}
     location /MAAS/ {
-        proxy_set_header Host $host;
+        proxy_set_header Host $http_host;
         proxy_set_header X-Real-IP $remote_addr;
-        proxy_set_header X-Forwarded-Host $host:$server_port;
+        proxy_set_header X-Forwarded-Host $http_host;
         proxy_set_header X-Forwarded-Server $host;
         proxy_set_header X-Forwarded-Proto $scheme;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;