Puppet users - Mar 2013 - Custom ensure instead of ensurable in type provider

Hi,

I''m currently writing a custom type for managing Windows environment 
variables.

A variable should be (re-)created if it doesn''t exist or the value
doesn''t
match the desired value. So exists? checks exactly this. It returns true 
only if the variable exists and the value matches.

This, however, creates a problem when the variable should be destroyed. 
When destroying a variable, I don''t care for the value anymore. I just
need
to know wether it exists or not. So I need to different tests 
(existswithvalue? and exists?).

My problem now is that I don''t know how to implement "ensure"
for this
case, as I cannot use "ensurable" in the type.

Thanks...

    Dirk

-- 
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-users+unsubscribe@googlegroups.com.
To post to this group, send email to puppet-users@googlegroups.com.
Visit this group at http://groups.google.com/group/puppet-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.

On Wednesday, March 13, 2013 5:31:09 AM UTC-5, dirk.he...@altum.de
wrote:
>
> Hi,
>
> I''m currently writing a custom type for managing Windows
environment
> variables.
>
> A variable should be (re-)created if it doesn''t exist or the value
doesn''t
> match the desired value. So exists? checks exactly this. It returns true 
> only if the variable exists and the value matches.
>
> This, however, creates a problem when the variable should be destroyed. 
> When destroying a variable, I don''t care for the value anymore. I
just need
> to know wether it exists or not. So I need to different tests 
> (existswithvalue? and exists?).
>
> My problem now is that I don''t know how to implement
"ensure" for this
> case, as I cannot use "ensurable" in the type.
>

Your problem is that you are conflating distinct (for your purposes) 
aspects of your resource''s state.  If you care at times whether the 
variable is declared at all or not, and at other times what its value is, 
then those should be separate properties.  Your resource declarations will 
then look like this:

env_var { ''AWESOMENESS'':
  value => ''meh'',
  # optional:
  ensure => present
}

or

env_var { ''AWESOMENESS'':
  ensure => absent
}


John

-- 
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-users+unsubscribe@googlegroups.com.
To post to this group, send email to puppet-users@googlegroups.com.
Visit this group at http://groups.google.com/group/puppet-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.

Am Mittwoch, 13. März 2013 17:00:18 UTC+1 schrieb jcbollinger:
>
>
> My problem now is that I don''t know how to implement
"ensure" for this
>> case, as I cannot use "ensurable" in the type.
>>
>
> Your problem is that you are conflating distinct (for your purposes) 
> aspects of your resource''s state.  If you care at times whether
the
> variable is declared at all or not, and at other times what its value is, 
> then those should be separate properties.  Your resource declarations will 
> then look like this:
>
> env_var { ''AWESOMENESS'':
>   value => ''meh'',
>   # optional:
>   ensure => present
> }
>
> or
>
> env_var { ''AWESOMENESS'':
>   ensure => absent
> }
>
I''ve changed the logic of exists? a bit to reflect this, and it works. 
However, one has to remember not to provide a value if "ensure =>
absent"
was specified. Or is there a way to check this in the provider?

Thanks...


-- 
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-users+unsubscribe@googlegroups.com.
To post to this group, send email to puppet-users@googlegroups.com.
Visit this group at http://groups.google.com/group/puppet-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.

On Thursday, March 14, 2013 2:28:13 AM UTC-5, dirk.he...@altum.de
wrote:
>
> Am Mittwoch, 13. März 2013 17:00:18 UTC+1 schrieb jcbollinger:
>
>>
>>
>> My problem now is that I don''t know how to implement
"ensure" for this
>>> case, as I cannot use "ensurable" in the type.
>>>
>>
>> Your problem is that you are conflating distinct (for your purposes) 
>> aspects of your resource''s state.  If you care at times
whether the
>> variable is declared at all or not, and at other times what its value
is,
>> then those should be separate properties.  Your resource declarations
will
>> then look like this:
>>
>> env_var { ''AWESOMENESS'':
>>   value => ''meh'',
>>   # optional:
>>   ensure => present
>> }
>>
>> or
>>
>> env_var { ''AWESOMENESS'':
>>   ensure => absent
>> }
>>
>
> I''ve changed the logic of exists? a bit to reflect this, and it
works.
> However, one has to remember not to provide a value if "ensure =>
absent"
> was specified.
>

That''s under your control.  Were I you, I would probably implement
flushing
for this resource type instead of applying changes directly in response to 
property changes.  See 
http://docs.puppetlabs.com/guides/provider_development.html#flushing.  That 
way your provider can act based on all of its properties together, instead 
of acting separately on each one.

Alternatively, your provider''s value=() method could condition its
behavior
on its resource''s should(:ensure) value (and perhaps vise versa, too),
so
that it does not perform needless operations.

 
> Or is there a way to check this in the provider?
>

There are validation and munging hooks for resource parameters, but they 
only work on a parameter-by-parameter basis.  As far as I know, there is no 
whole-resource validation hook built into the framework.


John

-- 
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-users+unsubscribe@googlegroups.com.
To post to this group, send email to puppet-users@googlegroups.com.
Visit this group at http://groups.google.com/group/puppet-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.

On Wed, 13 Mar 2013 09:00:18 -0700 (PDT)
jcbollinger <John.Bollinger@stJude.org> wrote:
> Your problem is that you are conflating distinct (for your purposes) 
> aspects of your resource''s state.  If you care at times whether
the
> variable is declared at all or not, and at other times what its value
> is, then those should be separate properties.  Your resource
> declarations will then look like this:
> 
> env_var { ''AWESOMENESS'':
>   value => ''meh'',
>   # optional:
>   ensure => present
> }
> 
> or
> 
> env_var { ''AWESOMENESS'':
>   ensure => absent
> }
> 
> 
> John
> 
I tend to disagree here. If the presence of an environment variable
inherently means that it has a value and the absence of a value
inherently means that the resource is absent I don''t see the point in
having two properties.

I''d suggest to not use ensurable and define the ensure property
yourself:

in your type:

    newproperty(:ensure) do
      newvalues :absent
      newvalues /.*/ # or whatever is valid for a value
    end

in your provider, drop exists?, create and destroy and use

    def ensure
      if value = get_environment_variable(resource[:name])
        value
      else
        :absent
      end
    end

    def ensure=(new_value)
      if new_value == :absent
        destroy_environment_variable(resource[:name])
      else
        set_environment_variable(resource[:name], new_value)
      end
    end

you can then either specify

    env_var { ''TMP'':
      ensure => ''C:\TEMP''
    }

or
    env_var { ''TMP'':
      ensure => absent,
    }

-Stefan

-- 
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-users+unsubscribe@googlegroups.com.
To post to this group, send email to puppet-users@googlegroups.com.
Visit this group at http://groups.google.com/group/puppet-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.

Can you publish your work on github.   I might be able to help it along.  

-- 
You received this message because you are subscribed to the Google Groups
"Puppet Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-users+unsubscribe@googlegroups.com.
To post to this group, send email to puppet-users@googlegroups.com.
Visit this group at http://groups.google.com/group/puppet-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.