Puppet custom function for arithmetic operation

[Ashish Jaiswal]

Hello,

Just trying to write a custom function. Basically looking to pass an
argument from manifest and value should get calculated.

module Puppet::Parser::Functions
newfunction(:shmmax, :type => :rvalue) do |args|
def shmmax(args)
product = args * 1024 * 1024 * 1024
return product
end
end
end


@ foo.pp
$shmmax_variable = shmmax(2)
sysctl { "kernel.shmmax" : val => $shmmax_variable }

In this case I'm expecting a value of 2147483648 for kernel.shmmax in
sysctl.conf file

Its just fails, Any pointer what is wrong here ?

Regards,
Ashish Jaiswal.

[jcbollinger]

Your custom function does not have the necessary form.  Most significantly, the block passed to newfunction() should perform the work of the function directly, not define a Ruby method to perform that work.  For rvalue functions, the value obtained by executing the block is the return value of the function.  Secondarily, the function arguments are presented to the function body as an array.  For example,

module Puppet::Parser::Functions
    newfunction(:shmmax, :type => :rvalue) do |args|

        args[0] * 1024 * 1024 * 1024
    end
end

Note that if you want to perform any argument validation then that's on you.

Note also that the function must appear in a Ruby file with the same base name as the function itself, and that although you should put your function in a module, you need to sync it into the master's lib directory before the master will use it.  Furthermore, be aware that if you change the function implementation then you must both sync the new function implementation into the master and restart the master, in that order, before your changes are effective.


John

[Ashish Jaiswal]

Hi John,

Thanks for the pointer, for workaround I used the inline_template function to work. Thanks for the piece of code. I will try this once I reach office, that would be on Monday.

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[Felix Frank]

On 11/08/2014 06:01 AM, Ashish Jaiswal wrote:
> Hi John,
>
> Thanks for the pointer, for workaround I used the inline_template
> function to work. Thanks for the piece of code. I will try this once I
> reach office, that would be on Monday.

Yeah, that's pretty expensive in case you're low on CPU.

Has that worked out for you?

[Ashish]

Hi Felix,

It was consuming lot of CPU and causing the host machine to get hanged.. I used the inline_template for the moment.

Any work around would be nice ??

I don’t know why it is causing hurt to cpu, cause its just a simple math out there. Let me know ??

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[Spencer Krum]

Puppet can actually do math inline:

$shmmax = 2 * 1024 * 1024 * 1024

notify { $shmmax: }

Maybe this is the easiest way to solve your problem?

Thanks,
Spencer

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