Hello! This is the two-part proposal to open-source periodic upstream server resolution and implement a dedicated service worker for nginx. The purpose of this e-mail is to describe the WHY and solicit feedback.
Nginx supports domain names in the upstream server configuration. Currently, domain names are resolved at configuration time only, and there are no subsequent name resolutions. There are plans to open-source re-resolvable upstream servers. This will allow applying DNS updates to upstream configurations in runtime. So, there is a need to support periodic asynchronous operations. And a dedicated service worker is a possible architectural way to address this. The master process reads and parses configuration and creates the service worker when needed (in a similar way to cache-related processes). The service worker manages periodic name resolutions and updates corresponding upstream configurations. The name resolution relies on the existing nginx resolver and upstream zone functionality. The service worker will be responsible solely for periodic background tasks and wouldn't accept client connections. The service worker should be the last worker process to shut down to maintain the actual state of upstreams when there are active workers. Alternative architecture considered was about choosing one of the regular workers (e.g., worker zero) to take care of periodic upstream server resolution, but it creates asymmetry in responsibilities and load for this dedicated worker. -- Vladimir Kokshenev _______________________________________________ nginx-devel mailing list -- nginx-devel@nginx.org To unsubscribe send an email to nginx-devel-le...@nginx.org
