Override a file{} directive - is it possible?

[Sean Carolan]

Maybe one of you can help with this. I have a class that's got a
file{} type directive in it. It populates /etc/security/limits.conf
with specific settings. I have a small handful of hosts where we want
to manage /etc/security/limits.conf manually. Is there a simple way
to tell puppet to exclude this file type just on those hosts, without
copying the entire class?

[Tim Mooney]

In regard to: [Puppet Users] Override a file{} directive - is it possible?,...:

Is there a way that puppet can detect these particular hosts? For
example, is it true for all hosts that are in a particular datacenter,
or for which some class (or even user) is present?

I ask, because the way you would typically do what you're asking is to
either use facts about systems to trigger the "don't manage
/etc/security/limits.conf" logic, or to have your manifests key on
external configuration that you keep in something like extlookup(),
hiera(), or your ENC (external node classifier).

So, there are several ways to accomplish what you're looking for, but
which one is best depends on your needs and how you actually detect that
hostB shouldn't have limits.conf managed.

You don't say what version of puppet you're using, whether you're using
an ENC, or whether you're already using either extlookup() or hiera(),
so it's really difficult to suggest something that integrates well with
your current environment.

I can give you two examples from my environment, though.

We're using puppet 2.7.14 without an ENC (we have dashboard but don't
use it for ENC purposes), but we are using hiera. The absolute easiest
way (but likely *not* best) way to do this would be to do this with
a hiera setting like:

common.yaml:
---
manage_limits_conf: 'yes'


host1.example.com.yaml:
---
manage_limits_conf: 'no'


and then in your manifest that sets up limits.conf, just wrap with the
appropriate logic to check hiera() whether it should be managed or not.


A second example would be if you have a fact (probably a custom fact)
that could be used to determine the exact set of systems for which
limits.conf should not be managed. For example, we have a custom fact
(location) that returns the name of the datacenter a system is located in.
If you wanted all the systems in location=datacenter1 to not manage
limits.conf, then you could wrap your file{} resource in a conditional
that tests the fact.

Certainly vague answers to your question, but hopefully this gives you
something to go on. If it's not enough to go on, provide more information
about your environment. That will hopefully make it easier for someone to
suggest a method that works well for your environment.

Tim
--
Tim Mooney Tim.M...@ndsu.edu
Enterprise Computing & Infrastructure 701-231-1076 (Voice)
Room 242-J6, IACC Building 701-231-8541 (Fax)
North Dakota State University, Fargo, ND 58105-5164

[Sean Carolan]

> You don't say what version of puppet you're using, whether you're using
> an ENC, or whether you're already using either extlookup() or hiera(),
> so it's really difficult to suggest something that integrates well with
> your current environment.

Sorry I didn't provide more detail. We're using puppet 2.6.13. We
have a single *.pp config file for each and every host, so specifying
additional classes is not hard to do on a host-per-host basis. Here's
the limits.conf config from the class that has been applied to these
hosts:

file { "/etc/security/limits.conf":
owner => "root",
group => "root",
mode => "644",
content => "#<domain>\t\t<type>\t\t<item>\t\t<value>\n*\t\t-\t\tnofile\t\t65000\n*\t\t-\t\tnproc\t\t140000\n*\t\thard\t\tcore\t\tunlimited\ncdc-dev\t\t-\t\tpriority\t\t15\nhtc\t\t-\t\tnofile\t\t250000\n";
}

Basically I just want this "file" type to not be active on three
hosts. I don't need to be able to detect the hosts, as I can specify
the config manually in each of their config files.

[Calvin Walton]

On Fri, 2012-08-17 at 15:41 -0700, Sean Carolan wrote:
> > You don't say what version of puppet you're using, whether you're using
> > an ENC, or whether you're already using either extlookup() or hiera(),
> > so it's really difficult to suggest something that integrates well with
> > your current environment.
>
> Sorry I didn't provide more detail. We're using puppet 2.6.13. We
> have a single *.pp config file for each and every host, so specifying
> additional classes is not hard to do on a host-per-host basis. Here's
> the limits.conf config from the class that has been applied to these
> hosts:

<snip>

> Basically I just want this "file" type to not be active on three
> hosts. I don't need to be able to detect the hosts, as I can specify
> the config manually in each of their config files.

It's not really the cleanest-looking thing, but the easiest option for
your particular case is to wrap the file resource in an if statement
like this:
if (! $::security_limits_disabled) {
file { '/etc/security/limits.conf':
...
}
}
then, on each of the nodes where you don't want to use the limits.conf
file, you can just set the variable to true:
node special_box {
include some_classes
$security_limits_disabled = true
}
--
Calvin Walton <calvin...@kepstin.ca>

[Sean Carolan]

> It's not really the cleanest-looking thing, but the easiest option for
> your particular case is to wrap the file resource in an if statement
> like this:
> if (! $::security_limits_disabled) {
> file { '/etc/security/limits.conf':
> ...
> }
> }

Thanks, this is just what I was looking for.

[Sean Carolan]

One last question, is it possible to do this:

class profile::server::java {
$security_limits_disabled = true
}

and then simply include that class on my target node? I tried to do
this but the file is still getting overwritten...

[Martin Alfke]

In this case you need to add the scope to the variable used in the if clause:
if ( ! $profile::server::java::security_limits_disabled) { ........ <- add class name as scope

hth,

Martin

[Sean Carolan]

>>>> It's not really the cleanest-looking thing, but the easiest option for
>>>> your particular case is to wrap the file resource in an if statement
>>>> like this:
>>>> if (! $::security_limits_disabled) {
>>>> file { '/etc/security/limits.conf':
>>>> ...
>>>> }
>>>> }

Super, thanks Martin!

[Keiran Sweet]

Another option worth mentioning, and this may not be suitable for your environment, is to allow host overrides of configuration files within your module using file precedence like the below.

    file { '/etc/security/limits.conf' :

        ensure  => file,

        mode    => 755,

        owner   => root,

        group   => root,

        source  => [   "puppet:///modules/modulename/limits.conf.$::hostname" ,

                             "puppet:///modules/modulename/limits.conf",

                   ],

    }

By default, all nodes get the standard limits.conf file that is served out from your module, however, if you create a limits.conf.oracleserver1 file that contains the required settings, the server oracleserver1 will get the overridden limits.conf file when it checks in.

This has been extremely useful in my environment when importing the odd 'unique snowflake' type server quickly without having to make any code/logic changes or introduce large numbers of ENC values to disable certain functionality or alter the flow of your puppet code.

Cheers,

K

[Sean Carolan]

> This has been extremely useful in my environment when importing the odd
> 'unique snowflake' type server quickly without having to make any code/logic
> changes or introduce large numbers of ENC values to disable certain
> functionality or alter the flow of your puppet code.

Yes. Puppet doesn't seem to deal with snowflakes well, thanks for sharing this.