Lighttpd

As of lighttpd 1.4.40 courtesy of issue #1584
https://redmine.lighttpd.net/issues/1584
changeset 1812f5541a1fffb720180f958cb36ae7a8fcab3d
https://redmine.lighttpd.net/projects/lighttpd/repository/14/revisions/1812f5541a1fffb720180f958cb36ae7a8fcab3d
added support for a -1 option allowing lighttpd to be run via xinetd.

For example:

    service lighttpd
    {
      type        = UNLISTED
      socket_type = stream
      protocol    = tcp
      port        = 8080
      wait        = no
      server      = /usr/sbin/lighttpd -1 -Df /etc/lighttpd/lighttpd.conf
    }

However, as mentioned in changeset 1812f5541a1fffb720180f958cb36ae7a8fcab3d,

> Note: lighttpd is designed as a high performance, long-running server,
> not a one-shot executable. This one-shot mode of operation has not been
> tuned for performance. lighttpd server start-up and initialization aims
> for correctness, not speed. If using this one-shot mode as part of fork
> and exec from xinetd, then performance is already not of high concern.

But, also since lighttpd version 1.4.40 courtesy of issue #2696
<https://redmine.lighttpd.net/issues/2696>
changeset 06b87dee346b91c36c3e7a461879f34e9900092b
https://redmine.lighttpd.net/projects/lighttpd/repository/14/revisions/06b87dee346b91c36c3e7a461879f34e9900092b
added support for a -i <secs> graceful shutdown timeout.

This is a feature request to make it possible to combine both options.

That way this xinetd configuration will become possible:

    service lighttpd
    {
      type        = UNLISTED
      socket_type = stream
      protocol    = tcp
      port        = 8080
      wait        = yes
      server      = /usr/sbin/lighttpd -i 3600 -1 -Df /etc/lighttpd/lighttpd.conf
    }

Notice the addition of "-i 3600" to the lighttpd command line and the change of the "wait" value from "no" to "yes".

When the "wait" value is "no", then xinetd goes ahead and calls `man 2 accept` on the listening socket and passes the resulting connected socket as fd 0 to lighttpd and xinetd continues to accept new connections and spawn more lighttpd processes without regard for whether or not any of the previously spawned ones have exited.

When the "wait" value is "yes", then xinetd does NOT call accept and instead passes the listening socket to the server as fd 0 and waits for the server executable to exit before it pays any attention to that listen socket again.

This feature request is for lighttpd to expect a listen socket as fd 0 instead of a connected socket if both -1 AND -i <secs> have been given as options.

With a lighttpd xinetd service configured this way, lighttpd will then start up the first time its listen port is accessed but then it will continue running and handling connections until it's been idle for 1 hour (in the case of the above example that uses "-i 3600") at which point it will gracefully exit and xinetd will start monitoring the listen socket for incoming connections again ready to start lighttpd all over again the next time its listen port is accessed.

In other words, web server on demand with none of the performance limitations of `wait = no` nor the resource implications of having a process running and idle that's not being used (on a machine with limited resources).

Note that systemd also supports both of the above xinetd configurations natively. For the "wait = yes" version you end up with a "lighttpd.socket" file that contains an "Accept=yes" line in the "[Socket]" section and an associated "lighttpd@.service" file. For the "wait = no" version you end up with a "lighttpd.socket" file that contains an "Accept=no" line in the "[Socket]" section and an associated "lighttpd.service" file.