closes #12168 nginx reverse proxy opds

docker/web_nginx.conf

@@ -111,6 +111,19 @@ server {
       return 429 '{"status": 429, "message": "Too Many Requests. Consider using https://openlibrary.org/developers/dumps."}';
     }
 
+    location /opds {
+        proxy_pass https://ol-opds.prod.archive.org/;
+
+        add_header X-OPDS-Backend "ol-opds.prod.archive.org" always;
+        proxy_set_header Host ol-opds.prod.archive.org;
+        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;
+
+        # optional but usually needed
+        proxy_redirect off;
+    }
+
     location / {
         limit_req zone=web_limit burst=100 delay=10;
         limit_req zone=ua_rate_limit burst=25 delay=10;