Grafana: pass Host HTTP header

roles/grafana/templates/nginx-location.conf.j2

@@ -2,6 +2,7 @@
 location /grafana/ {
 	proxy_http_version 1.1;
 	proxy_pass http://127.0.0.1:3000/;
+	proxy_set_header Host $http_host;
 }
 
 location /grafana/render/ {
@@ -20,6 +21,8 @@ location /grafana/render/ {
 
 	proxy_ignore_headers Cache-Control Expires;
 
+	proxy_set_header Host $http_host;
+
 	limit_req zone=grafana-limit burst=10;
 
 	expires 150s;