chore(nginx): use environment variables for gunicorn

config/root/etc/nginx/nginx.conf

@@ -9,6 +9,10 @@ worker_processes auto;
 worker_cpu_affinity auto;
 pid /run/nginx.pid;
 
+# gunicorn
+env LISTEN_HOST;
+env LISTEN_PORT;
+
 # link configuration
 env CIPHERSERVER_PORT_8001_TCP_ADDR;
 env CIPHERSERVER_PORT_8001_TCP_PORT;
@@ -130,7 +134,17 @@ http {
 
         # Authentication and proxying
         location / {
-            proxy_pass http://127.0.0.1:8080;
+            # gunicorn host
+            set_by_lua_block $gunicorn_host {
+                return os.getenv('LISTEN_HOST') or '127.0.0.1'
+            }
+
+            # gunicorn port
+            set_by_lua_block $gunicorn_port {
+                return os.getenv('LISTEN_PORT') or '8080'
+            }
+
+            proxy_pass http://$gunicorn_host:$gunicorn_port;
             proxy_set_header Host localhost:$proxy_port;
             proxy_set_header X-Forwarded-Host $x_forwarded_host;
             proxy_set_header X-Forwarded-Port $x_forwarded_port;