Puppet users - Sep 2012 - How can I ensure that a service is started/stopped based on if it is needed or not ?

I have a several services that I use only for some sites and I would like 
to make sure it is started when a site that uses is activated and stopped 
when it is not needed anymore.

Examples: memcache, elasticsearch, rabbitmq, etc.

I can easily make a service virtual and realize it before making a 
reference to it like this:

class webserver {
  @service {"memcache":
    ensure => running,
  }
}

class sites {
  Realize[''memcache'']
  site {"example.com":
    require => Service[''memcache'']
  }
}

But this will not stop the service if it is never realized.

Any ideas ?

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You could create a fact that returns true or false, then use that fact in your
puppet code to determine whether to start the service.  I''d need more
details to really say that''s the best solution though.  Other options
would be to use heira or to use a parameterized class and set those parameters
in your ENC/mode definition.

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I am not experienced in creating facts, could you give me a better idea ? I 
fail to see how a fact could detect if a service is required.
Thanks

On Saturday, 8 September 2012 23:57:50 UTC-4, Glenn Poston
wrote:
>
> You could create a fact that returns true or false, then use that fact in 
> your puppet code to determine whether to start the service.  I''d
need more
> details to really say that''s the best solution though.  Other
options would
> be to use heira or to use a parameterized class and set those parameters in
> your ENC/mode definition.
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On 09/09/2012 06:38 AM, Sébastien Lavoie wrote:
> I am not experienced in creating facts, could you give me a better idea
> ? I fail to see how a fact could detect if a service is required.
And how do you determine if it''s required? By hostname, or?


-- 
Jakov Sosic
www.srce.unizg.hr

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----- Original Message -----
> From: "Sébastien Lavoie" <sebastien@lavoie.sl>
> To: puppet-users@googlegroups.com
> Sent: Friday, September 7, 2012 11:32:55 PM
> Subject: [Puppet Users] How can I ensure that a service is started/stopped
based on if it is needed or not ?
> 
> I have a several services that I use only for some sites and I would
> like to make sure it is started when a site that uses is activated
> and stopped when it is not needed anymore.
> 
> 
> Examples: memcache, elasticsearch, rabbitmq, etc.
> 
> 
> I can easily make a service virtual and realize it before making a
> reference to it like this:
> 
> 
> class webserver {
> @service {"memcache":
> ensure => running,
> }
> }
> 
> 
> class sites {
> Realize[''memcache'']
> site {"example.com":
> require => Service[''memcache'']
> }
> }
> 
> 
> But this will not stop the service if it is never realized.
dont know if this helps but lets say you have a common class
you install on all nodes:

class common {
   include memcache
}

class memcache {
   service{"memcache": ensure => stopped, enable => false}
}

at this point if you include common on all machines memcache will
be stopped and disabled everywhere

now you make a class specifically to include on nodes that needs
it running.

class memcache::enable inherits memcache {
   Service["memcache"] { ensure => running, enable => true }
}

if you include this class on a node it will be enabled, soon
as you remove the class it will be disabled again

Generally though this is a bad idea because you also have to
consider configs, packages and all this stuff it might make
sense in your case but I think the correct thing to do is just
not to install stuff on machines that you dont need.

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@Jakov I am currently running Puppet on a single host, it is only to manage 
site configurations, so this is not a problem
@R.I. Thanks, worked like a charm. Bonus points for very simple solution.


On Sunday, September 9, 2012 7:34:10 AM UTC-4, R.I. Pienaar
wrote:
>
>
>
> ----- Original Message ----- 
> > From: "Sébastien Lavoie" <seba...@lavoie.sl
<javascript:>>
> > To: puppet...@googlegroups.com <javascript:> 
> > Sent: Friday, September 7, 2012 11:32:55 PM 
> > Subject: [Puppet Users] How can I ensure that a service is 
> started/stopped based on if it is needed or not ? 
> > 
> > I have a several services that I use only for some sites and I would 
> > like to make sure it is started when a site that uses is activated 
> > and stopped when it is not needed anymore. 
> > 
> > 
> > Examples: memcache, elasticsearch, rabbitmq, etc. 
> > 
> > 
> > I can easily make a service virtual and realize it before making a 
> > reference to it like this: 
> > 
> > 
> > class webserver { 
> > @service {"memcache": 
> > ensure => running, 
> > } 
> > } 
> > 
> > 
> > class sites { 
> > Realize[''memcache''] 
> > site {"example.com": 
> > require => Service[''memcache''] 
> > } 
> > } 
> > 
> > 
> > But this will not stop the service if it is never realized. 
>
> dont know if this helps but lets say you have a common class 
> you install on all nodes: 
>
> class common { 
>    include memcache 
> } 
>
> class memcache { 
>    service{"memcache": ensure => stopped, enable => false} 
> } 
>
> at this point if you include common on all machines memcache will 
> be stopped and disabled everywhere 
>
> now you make a class specifically to include on nodes that needs 
> it running. 
>
> class memcache::enable inherits memcache { 
>    Service["memcache"] { ensure => running, enable => true
}
> } 
>
> if you include this class on a node it will be enabled, soon 
> as you remove the class it will be disabled again 
>
> Generally though this is a bad idea because you also have to 
> consider configs, packages and all this stuff it might make 
> sense in your case but I think the correct thing to do is just 
> not to install stuff on machines that you dont need. 
>
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