Re: “Executable” StartupItems are preferred over “script” StartupItems

[macports at parvis.nl]

> On 2018-05-15, at 21:40, Rainer Müller <raimue at macports.org> wrote:
> 
> On 2018-05-15 20:57, macports at parvis.nl wrote:
>> 
>>> On 2018-05-15, at 03:56, Ryan Schmidt <ryandesign at macports.org> wrote:
>>> 
>>> 
>>> On May 14, 2018, at 11:13, macports at parvis.nl wrote:
>>> 
>>>> The Guide states “Executable” StartupItems are preferred over “script” StartupItems. 
>>>> 
>>>> I have 2 daemons that are Perl scripts, they can run "executable", but the previous version of the port used a "script".
>>>> Any reason not to change that?
>>> 
>>> Yes, executables are preferred. That way, launchd can monitor their lifetime.
>>> 
>>> Can you elaborate on what your portfiles were doing before? There may be reasons why they weren't using executables directly, but without seeing how they were set up, it's impossible to say.
>> 
>> Portfile munin @1.4.7:
>> ---
>> startupitem.create  yes
>> startupitem.name    munin-node
>> startupitem.start   "${prefix}/sbin/munin-node"
>> startupitem.stop    "kill `cat ${prefix}/var/run/munin/munin-node.pid`"
>> ---
>> 
>> /opt/local/sbin/munin-node is a perl program. I see see no reason for daemondo here. launchd KeepAlive would only keep daemondo alive, not the executed munin-node.
> 
> The generated startupitems will always make use of daemondo. The purpose
> is to turn signals received from launchd into the appropriate action for
> the daemon process.

I know.

> It looks like munin-node will fork itself into the background by
> default. This is incompatible with launchd, as it would assume the
> process died as soon as you launch it. Unless there is a switch or
> configuration option to force it to run as a foreground process, you
> need to use "script" instead of "executable".

No, munin-node doesn't fork itself into the background. It does fork for sub-processes. 
Also, I'm running munin node as executable from launchd and it works fine.

> However, I would let daemondo handle the stop command by telling it
> where to find the pidfile written by the daemon:
> 
> startupitem.create  yes
> startupitem.name    munin-node
> startupitem.start   ${prefix}/sbin/munin-node
> startupitem.pidfile clean ${prefix}/var/run/munin/munin-node.pid
> startupitem.netchange yes

That is the way it was done.

> As the munin-node daemon opens a TCP server socket, the port should also
> use startupitem.netchange to ensure the daemon is restarted when the
> network changes in order to bind to the new interface address.

I don't know how to do that in a launchd plist, but since munin-node acts on request only, I think it is not a terrible waste to let it run when the network goes down.

> Rainer

paul.