fix(docker): use a tunable for fastapi proxy host value

On aur-dev.archlinux.org, we use a proxy tunnel through our
internal nginx. This allows us to rewrite the Host header
based on whatever port we wish within internal nginx config.

Signed-off-by: Kevin Morris <kevr@0cost.org>

docker-compose.aur-dev.yml

@@ -69,6 +69,8 @@ services:
       - data:/data
 
   nginx:
+    environment:
+      - NGINX_PROXY_PORT=443
     restart: always
     volumes:
       - data:/data

docker-compose.yml

@@ -244,7 +244,8 @@ services:
     image: aurweb:latest
     init: true
     environment:
-      - AUR_CONFIG=conf/config
+      # Proxy toward FastAPI.
+      - NGINX_PROXY_PORT=8444
     entrypoint: /docker/nginx-entrypoint.sh
     command: /docker/scripts/run-nginx.sh
     ports:

docker/config/nginx.conf

@@ -136,7 +136,7 @@ http {
 
         location / {
             proxy_pass http://asgi_backend;
-            proxy_set_header Host $http_host;
+            proxy_set_header Host HTTP_HOST;
             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
             proxy_set_header X-Forwarded-Proto $scheme;
             proxy_set_header X-Forwarded-Ssl on;

docker/nginx-entrypoint.sh

@@ -21,4 +21,8 @@ fi
 
 cp -vf /docker/config/nginx.conf /etc/nginx/nginx.conf
 
+# NGINX_PROXY_PORT must be defined for the `nginx` service
+# within `docker-compose.yml`.
+sed -i "s|HTTP_HOST|\$host:${NGINX_PROXY_PORT}|g" /etc/nginx/nginx.conf
+
 exec "$@"