[gentoo-dev] rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[gentoo-dev] rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[William Hubbs]

[-- Attachment #1: Type: text/plain, Size: 840 bytes --]

All,

there is a branch in the OpenRC github repo called supervisor.

On that branch, I am working on a lightweight daemon supervisor that
will be native to OpenRC.

It is based on start-stop-daemon, but it will stay around and make sure
that the daemon gets restarted if it dies.

It is still very rough, and not ready for production, but at this point
I would like to make everyone aware that it exists and  ask folks to go
over the code and provide comments.

It can currently launch a daemon, and I still am working on making it
restart a daemon if it dies.

This will only work for non-forking daemons; the daemon should not fork
and should not write a pid file.

One of the big questions I have is about PAM usage. Do I still need to
do that in this supervisor? If I open a PAM session, does it carry
across forks?

Thanks,

William


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [gentoo-dev] rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[James Le Cuirot]

[-- Attachment #1: Type: text/plain, Size: 1139 bytes --]

On Tue, 16 Feb 2016 12:51:17 -0600
William Hubbs <williamh@gentoo.org> wrote:

> there is a branch in the OpenRC github repo called supervisor.

Interesting!

> It is still very rough, and not ready for production, but at this
> point I would like to make everyone aware that it exists and  ask
> folks to go over the code and provide comments.

I'm not really qualified to comment on the code but I'm aware that
there are lot of ways to get this wrong so please do your homework if
you haven't done so already. Your post seems like a good start. :)

runit seems highly regarded and we use it at work on CentOS to allow
users of the same UNIX group to manage a collection of processes
without requiring root or sudo. I wasn't aware of s6 at the time but
I've heard that's also good and this makes an interesting read.

http://skarnet.org/software/s6/why.html

I wonder if it might even make more sense to reuse one of these instead
of reinventing the wheel. They are both extremely lightweight. If you
feel you can do better though then go for it!

Regards,
-- 
James Le Cuirot (chewi)
Gentoo Linux Developer

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 951 bytes --]

Re: [gentoo-dev] rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[William Hubbs]

[-- Attachment #1: Type: text/plain, Size: 1795 bytes --]

On Tue, Feb 16, 2016 at 07:32:08PM +0000, James Le Cuirot wrote:
> On Tue, 16 Feb 2016 12:51:17 -0600
> William Hubbs <williamh@gentoo.org> wrote:
> 
> > there is a branch in the OpenRC github repo called supervisor.
> 
> Interesting!
> 
> > It is still very rough, and not ready for production, but at this
> > point I would like to make everyone aware that it exists and  ask
> > folks to go over the code and provide comments.
> 
> I'm not really qualified to comment on the code but I'm aware that
> there are lot of ways to get this wrong so please do your homework if
> you haven't done so already. Your post seems like a good start. :)
 
That's exactly why I posted it; I know this is a complex issue, so I
want others to look over the code and provide suggestions for cleaning
it up before it goes mainline.

> runit seems highly regarded and we use it at work on CentOS to allow
> users of the same UNIX group to manage a collection of processes
> without requiring root or sudo. I wasn't aware of s6 at the time but
> I've heard that's also good and this makes an interesting read.
> 
> http://skarnet.org/software/s6/why.html
> 
> I wonder if it might even make more sense to reuse one of these instead
> of reinventing the wheel. They are both extremely lightweight. If you
> feel you can do better though then go for it!

We have s6 support in OpenRC, and I am looking at integrating runit
support as well.

For s6 info, see the s6-guide.md file located in
/usr/share/doc/openrc-*.

This is experimental work at this point, because I've been asked to
determine how much work would be involved in having a small light-weight
supervisor in OpenRC directly.

> Regards,
> -- 
> James Le Cuirot (chewi)
> Gentoo Linux Developer

William


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [gentoo-dev] rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[James Le Cuirot]

[-- Attachment #1: Type: text/plain, Size: 778 bytes --]

On Tue, 16 Feb 2016 16:04:42 -0600
William Hubbs <williamh@gentoo.org> wrote:

> > I wonder if it might even make more sense to reuse one of these
> > instead of reinventing the wheel. They are both extremely
> > lightweight. If you feel you can do better though then go for it!  
> 
> We have s6 support in OpenRC, and I am looking at integrating runit
> support as well.
> 
> For s6 info, see the s6-guide.md file located in
> /usr/share/doc/openrc-*.

Oh, that's cool! Now I come to think of it, I believe it was this
effort that made me aware of s6 in the first place but I'd forgotten
about it since. Now I feel dumb. As you were then. You're doing
great work and we're clearly spoilt for choice. :)

-- 
James Le Cuirot (chewi)
Gentoo Linux Developer

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 951 bytes --]

[gentoo-dev] Re: rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[Duncan]

James Le Cuirot posted on Tue, 16 Feb 2016 22:19:44 +0000 as excerpted:

> Oh, that's cool! Now I come to think of it, I believe it was this effort
> that made me aware of s6 in the first place but I'd forgotten about it
> since. Now I feel dumb.

Umm... I think there was supposed to be a break, here...

> As you were then. You're doing great work and
> we're clearly spoilt for choice. :)

... because as it was written, it appeared to be...

"Now I feel dumb.  As you were [dumb] then."

Which is how I originally read it, but it'd didn't seem to make any sense 
at all given the context, so I had to go back and figure out where my 
parsing went wrong, and decided it was a missing break.

Just in case anyone else reads that wrong, as I did initially.  
Unfortunately, I write things that end up reading totally not the way I 
intended too, from time to time.  I /hate/ it when that happens! =:^(

... Unless of course a sneaky insult was actually intended! ;^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

Re: [gentoo-dev] Re: rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[Daniel Campbell]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

On 02/16/2016 07:49 PM, Duncan wrote:
> James Le Cuirot posted on Tue, 16 Feb 2016 22:19:44 +0000 as
> excerpted:
> 
>> Oh, that's cool! Now I come to think of it, I believe it was this
>> effort that made me aware of s6 in the first place but I'd
>> forgotten about it since. Now I feel dumb.
> 
> Umm... I think there was supposed to be a break, here...
> 
>> As you were then. You're doing great work and we're clearly
>> spoilt for choice. :)
> 
> ... because as it was written, it appeared to be...
> 
> "Now I feel dumb.  As you were [dumb] then."
> 
> Which is how I originally read it, but it'd didn't seem to make any
> sense at all given the context, so I had to go back and figure out
> where my parsing went wrong, and decided it was a missing break.
> 
> Just in case anyone else reads that wrong, as I did initially. 
> Unfortunately, I write things that end up reading totally not the
> way I intended too, from time to time.  I /hate/ it when that
> happens! =:^(
> 
> ... Unless of course a sneaky insult was actually intended! ;^)
> 
IMO you're over-thinking it. I read it as "As you were, then", which
is a common saying in the (American, at least) military advising one
to keep doing what they're doing, or return to a resting position. :)

- -- 
Daniel Campbell - Gentoo Developer
OpenPGP Key: 0x1EA055D6 @ hkp://keys.gnupg.net
fpr: AE03 9064 AE00 053C 270C  1DE4 6F7A 9091 1EA0 55D6
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=O3dl
-----END PGP SIGNATURE-----

[gentoo-dev] Re: rfc: supervise-daemon -- a lightweight openrc daemon supervisor

[Duncan]

Daniel Campbell posted on Tue, 16 Feb 2016 22:30:45 -0800 as excerpted:

> IMO you're over-thinking it. I read it as "As you were, then", which is
> a common saying in the (American, at least) military advising one to
> keep doing what they're doing, or return to a resting position. :)

Yes.  That's how I read it too... with the direct military reference in 
my head... but only _after_ realizing my first read simply didn't make 
sense in context.

But I agree, that's almost certainly what was intended, which was why I 
decided there was a missing break, so that "As you were, then", could 
take on the military meaning, which in my (no-military-experience) mind 
at least, generally comes after a pause, represented by a break, in 
print.  Without that, I saw it as continuation of the previous thought, 
with its connections with "dumb".

And knowing from hard experience how easy it is to type something that 
ends up being misread across continents and cultures, I thought it best 
to mention the missing break, tho in hindsight I also should have been 
explicit about the military reference of the positive interpretation, as 
well, as while I considered it obvious once the break was there, now that 
I think about it, it's equally likely (if not more so) to be missed, by 
anyone not particularly familiar with the cultural reference.

So thanks for making the military reference explicit.  I saw it on second 
read, but failed to make it explicit, thus inviting misinterpretation, 
myself.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman