Hi, I am proposing to add a fcntl() command that would allow processes to "self document" file descriptors - making this description available through /proc/pid/fdinfo/fd, for netstat, lsof and friends to report. I don't have experience proposing interface changes. I thought I'd give more context here first, asking if that makes sense, and if obvious traps, previous discussions or alternative solutions come to mind. The technical implementation I have adds an fcntl command (F_SET_DESCRIPTION), a description member to struct file, and modifies show_fdinfo() for the generic proc fd class to eventually report it. If that sounds reasonable I'll happily follow up with a patch (and a shorter description) Thanks! More context and motivation below: For monitoring and debugging purposes, and during troubleshooting sessions, it is often needed to quickly identify the role of an established socket for a given process, or more globally for a group of significant sockets, such as all AF_INET/INET6 sockets. The available tools today let us try to infer this information from the available (proto, host, port) tuples - but frequently these days it boils down to HTTPs on generic load balancing or CDN endpoints, providing little information about what is served behind a socket. A way to improve that would be to allow processes to self-document their dependencies, and attach additional information to their sockets, in the form of a label or description string, somehow in the same way setproctitle/prctl can be used to give hints about spawned subprocesses roles. Example usage/contexts that come to mind: - netstat, ss, lsof having more details for users - modern browsers often having lots of open tabs, and service worker related connections, and a system user trying to identify the source of some network activity at the time it is observed - reading website names instead of CDN endpoints - looking at some remote connections in a distributed system and knowing the role of a couple stuck Send-Q sockets right away - remember the intent for a connection (say, the target host of an HTTP request, a database name, a data channel, ..) before information is lost during resolution to a destination host, and attach this information to the socket
