[uuoc]

And yet, socket activation is nothing new:

inetd: https://en.wikipedia.org/wiki/Inetd

xinetd: https://en.wikipedia.org/wiki/Xinetd

Used in the "olden" days to allow a single server to serve a bunch of services, not all of which are being used all of the time, to a bunch of clients, by only activating them when they are used.

[chatmasta]

Does systemd socket activation offer any advantages over xinetd?

[justinsaccount]

Afaik something like xinetd forks and execs a copy of the daemon for each connection and communicates over stdin/stdout.

This can work for simple services like sshd which fork for each connection anyway, but would never work for something like nginx or redis.

[JdeBP]

That is untrue. Read about "wait"/"nowait" (in the xinetd and inetd manuals, for starters).

[justinsaccount]

Ah, I must have been thinking of something like

https://cr.yp.to/ucspi-tcp/tcpserver.html

[JdeBP]

Then you'll enjoy reading about the nosh toolset and s6-networking, which both separate the listen-accept model into separate programs and have the ability to invoke "wait" servers with the listening socket.

* http://homepage.ntlworld.com./jonathan.deboynepollard/Softwa... * http://homepage.ntlworld.com./jonathan.deboynepollard/FGA/UC... * http://skarnet.org/software/s6-networking/

[Dylan16807]

Avoiding extra processes is good, but it's not the end of the world to exec netcat.

[eeperson]

Yes, it can also support local sockets as well as network sockets.

[papaf]

It has one terrifying disadvantage. The socket is opened and appears to be owned by pid 1.

I haven't seen the code that does this, but my hope is that it is perfect in every way - if not then its an open door from the internet into my server.