Puppet users - May 2011 - issue with exported resources and subscribe

Hello list,

I have a situation where if I have a hosts file generated by exported
resources it does not trigger a service restart unlike if it was
subscribing on a file that gets copied over via puppet. An example
would explain it better.

it should be noted that exported resources work fine.

class dnsmasq {
  file { "/etc/hosts":
        owner   => "root",
        group   => "root",
        mode    => "644",
        source  => "puppet:///modules/dnsmasq/hosts",
  }

  ...

  service { dnsmasq:
        ensure     => running,
        enable     => true,
        pattern    => "dnsmasq",
        subscribe  => File["/etc/dnsmasq.conf","/etc/dnsmasq-
local.conf","/etc/hosts"],
        hasrestart => true,
    }

So with the above if i change the file on the master then it will push
out to all hosts that include the dnsmasq class and restart the
dnsmasq service, all is good.

How ever if I generate the data using exported resources nothing
happens

Below doesn''t work

class dnsmasq {
  Host<<| tag == "all_hosts" |>>

  service { dnsmasq:
        ensure     => running,
        enable     => true,
        pattern    => "dnsmasq",
        subscribe  => File["/etc/dnsmasq.conf","/etc/dnsmasq-
local.conf","/etc/hosts"],
        hasrestart => true,
    }
}


// seperate class with /etc/hosts defined
class hosts {
  file { "/etc/hosts":
    owner   => "root",
    group   => "root",
    mode    => "644",
  }

  host { ''localhost'':
    ip => ''127.0.0.1'',
    host_aliases => ''localhost.localdomain'',
  }
  ... a few default hosts...
}


So my issue is that on all machines the hosts files are managed fine,
however on my internal dns servers that collect all the IPs of all
machines in the network whilst collecting the hosts files fine, the
dnsmasq service is never restarted, meaning i need to log into each
machine and manually restart dnsmasq to pick up the changes after a
new host is added to the system.

Any ideas?

Thanks
Nathan

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Hi,

In my exported resource manifests, if using code like:

  File <<| tag == "nagios::target"  |>> { notify =>
Service["nagios3"] }

Does that work for you?

Cheers,
Greg

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On May 5, 1:00 am, Nathan <pheni...@gmail.com>
wrote:
> Hello list,
>
> I have a situation where if I have a hosts file generated by exported
> resources it does not trigger a service restart unlike if it was
> subscribing on a file that gets copied over via puppet. An example
> would explain it better.
>
> it should be noted that exported resources work fine.
>
> class dnsmasq {
>   file { "/etc/hosts":
>         owner   => "root",
>         group   => "root",
>         mode    => "644",
>         source  => "puppet:///modules/dnsmasq/hosts",
>   }
>
>   ...
>
>   service { dnsmasq:
>         ensure     => running,
>         enable     => true,
>         pattern    => "dnsmasq",
>         subscribe  =>
File["/etc/dnsmasq.conf","/etc/dnsmasq-
> local.conf","/etc/hosts"],
>         hasrestart => true,
>     }
>
> So with the above if i change the file on the master then it will push
> out to all hosts that include the dnsmasq class and restart the
> dnsmasq service, all is good.
>
> How ever if I generate the data using exported resources nothing
> happens
>
> Below doesn''t work
>
> class dnsmasq {
>   Host<<| tag == "all_hosts" |>>
>
>   service { dnsmasq:
>         ensure     => running,
>         enable     => true,
>         pattern    => "dnsmasq",
>         subscribe  =>
File["/etc/dnsmasq.conf","/etc/dnsmasq-
> local.conf","/etc/hosts"],
>         hasrestart => true,
>     }
>
> }
>
> // seperate class with /etc/hosts defined
> class hosts {
>   file { "/etc/hosts":
>     owner   => "root",
>     group   => "root",
>     mode    => "644",
>   }
>
>   host { ''localhost'':
>     ip => ''127.0.0.1'',
>     host_aliases => ''localhost.localdomain'',
>   }
>   ... a few default hosts...
>
> }
>
> So my issue is that on all machines the hosts files are managed fine,
> however on my internal dns servers that collect all the IPs of all
> machines in the network whilst collecting the hosts files fine, the
> dnsmasq service is never restarted, meaning i need to log into each
> machine and manually restart dnsmasq to pick up the changes after a
> new host is added to the system.
>
> Any ideas?

Yes.

To get this sort of thing right, you need to think in terms of
Puppet''s logical model of the managed system, as opposed to in terms
of the observable result of Puppet''s work.  In particular, as far as
Puppet is concerned, managing file /etc/hosts via a File resource is
logically distinct from managing entries in that file via Host
resources.  File["/etc/hosts"] will trigger subscribers if it itself
needs to apply any changes, but it doesn''t know anything about Host
resources.  Indeed, it is possible that on some systems, Host
resources do not physically manifest in that file.

In your all-local example, File["/etc/hosts"] manages the content of
the /etc/hosts file (source => ...), so it triggers
Service["dnsmasq"]
when that content changes.  In your exported-resource example, File["/
etc/hosts"] manages only the existence, ownership, and mode of the
file -- not its contents -- so it only notifies subscribers if one of
those things is changed.

You need Service["dnsmasq"] to subscribe to all the Host resources,
or, as Greg suggested, you need the Host entries to notify the
Service.


John

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>
> To get this sort of thing right, you need to think in terms of
> Puppet''s logical model of the managed system, as opposed to in
terms
> of the observable result of Puppet''s work.  In particular, as far
as
> Puppet is concerned, managing file /etc/hosts via a File resource is
> logically distinct from managing entries in that file via Host
> resources.  File["/etc/hosts"] will trigger subscribers if it
itself
> needs to apply any changes, but it doesn''t know anything about
Host
> resources.  Indeed, it is possible that on some systems, Host
> resources do not physically manifest in that file.
>
> In your all-local example, File["/etc/hosts"] manages the content
of
> the /etc/hosts file (source => ...), so it triggers
Service["dnsmasq"]
> when that content changes.  In your exported-resource example, File["/
> etc/hosts"] manages only the existence, ownership, and mode of the
> file -- not its contents -- so it only notifies subscribers if one of
> those things is changed.
>
> You need Service["dnsmasq"] to subscribe to all the Host
resources,
> or, as Greg suggested, you need the Host entries to notify the
> Service.
>
> John
John, Greg,

Thanks for the tips, once I forced the hosts resources to notify the
service all is working as intended, thanks!

Nathan

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