systemd (Was Re: tmpfs for strategic directories)

[Josh Boyer]

On Wed, May 26, 2010 at 12:27:38PM -0400, seth vidal wrote:
>On Wed, 2010-05-26 at 18:20 +0200, Lennart Poettering wrote:
>> On Wed, 26.05.10 15:52, Scott James Remnant (scott at canonical.com) wrote:
>> 
>> > On Wed, 2010-05-26 at 08:43 -0400, Matthias Clasen wrote:
>> > 
>> > > On Wed, 2010-05-26 at 12:35 +0100, Scott James Remnant wrote:
>> > > 
>> > > > We did sit down and discuss things, and you convinced me that
>> > > > launchd-style activation was a useful thing to have.  Then you went off
>> > > > and wrote systemd anyway.
>> > > > 
>> > > 
>> > > If you want to add socket passing to upstart as well, we can turn this
>> > > into a win-win situation instead of flaming each other. 
>> > > 
>> > > If both upstart systemd support this in the same way, it will will be
>> > > much easier to get the patches for the various services upstream. That
>> > > is great. 
>> > > 
>> > I don't see any reason not to at least pass the LISTEN_FDS environment
>> > variable (though I can't figure out what LISTEN_PID is for?)
>> 
>> Ah nice, now we are talking, yesterday you were still refusing
>> cooperation on this, and claimed the systemd scheme was "too simple"...
>> 
>> Regarding the LISTEN_PID env var:
>> 
>> environment variables are normally inherited when forking/execing. We
>> want to make sure that only the process we actually start ourselves
>> parses and handles LISTEN_FDS. We want to avoid that if this daemon
>> might spawn some other process, it might get confused into handling
>> LISTEN_FDS, although that env var wasn't actually intended for it.
>> 
>> And hence we say that LISTEN_PID should be verified first, and only if
>> it matches LISTEN_FDS should be handled.
>> 
>> This is actually explained in my long blog story. Please read it. It's
>> number 8 in the feature list!
>> 
>> > Upstart will support a different mechanism as well though, because for
>> > the services we want to activate this way in Ubuntu, there are benefits
>> > to having the services "phone back" to Upstart to pick up the socket.
>> 
>> Right, would be good if you could elaborate about that. I alead asked
>> you a couple of times about this. Would love to hear about the
>> reasoning.
>
>Scott, Lennart,
>  A Proposal: maybe the two of you should continue this discussion
>off-list, in private. It may help facilitate more open communication
>since neither of you will feel you have to respond to things for an
>audience and you won't get any extraneous remarks from the peanut
>gallery (like myself).
>Perhaps there is more common ground than there appeared at first. If so
>- feeling it out in private may help all of us.

Also, while I certainly don't want to discourage a techincal discussion on
the devel list, I would think much of this conversation should have been had on
the systemd-devel list instead.  At least it wouldn't have gotten lost there.

josh