enhancement: systemd socket activation, service and target files

[jimc]

Context

I wanted to set up service for occasional testing across 5 computers in home network, xinetd/inetd style, but systemd is the new way of doing things. A bit of reading here http://0pointer.de/blog/projects/socket-activation2.html suggests its not too hard, but its always easier to ask first.

• Version of iperf3:

3.5. But I searched issues for systemd, which any feature request would refer to. And this premature submission was accidental... updating incrementally..

• Hardware:

linux on x86 & rpi

• Operating system (and distribution, if any):

Name : iperf3 Version : 3.5 Release : 1.fc28 Architecture: x86_64 Install Date: Thu 24 May 2018 02:51:33 PM MDT

Enhancement Request

• Current behavior

xinetd operation works iirc (tried many years ago). I think this means that systemd compatibility is close to trivial.

• Desired behavior

use socket opened by systemd then various systemd features can help workaround other bugs (like too many open files) where wait/nowait (inetd vocabulary) can fix.

• Implementation notes

http://0pointer.de/blog/projects/socket-activation.html http://0pointer.de/blog/projects/socket-activation2.html

[bmah888]

Thanks for the suggestion. Does contrib/iperf3.service not do what you need?

[thelounge-zz]

a .service file alone hardly is enough for socket activation, you need a .socket file and the dameon must suport it, just read the links above - the point is that PID1 ist listening and starts the process on-demand and handover the socket connection and when all works perfectly stops the .service unit when it's no longer used so that no process is running idle

[thelounge-zz]

to make it clear: that below is a dead simple (in that case udp) service using the systemd-socket

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <arpa/inet.h> #include <netinet/in.h> #include <sys/types.h> #include <sys/socket.h> #include <systemd/sd-daemon.h> #define MAXLINE 1024 int main() { if(sd_listen_fds(0) != 1) { fprintf(stderr, "No or too many file descriptors received\n"); exit(EXIT_FAILURE); } int len; int sockfd; char buffer[MAXLINE]; char *pong = "PONG\n"; struct sockaddr_in6 servaddr, cliaddr; sockfd = SD_LISTEN_FDS_START + 0; memset(&servaddr, 0, sizeof(servaddr)); memset(&cliaddr, 0, sizeof(cliaddr)); while(1) { recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, (struct sockaddr *) &cliaddr, &len); sendto(sockfd, (const char *)pong, strlen(pong), MSG_CONFIRM, (const struct sockaddr *) &cliaddr, len); } }