[et-mgmt-tools] passing list/dictionary in ksmeta

[Michael DeHaan]

adamwolf at feelslikeburning.com wrote:
>> Hennessey Daniel wrote:
>>     
>>> Hey people,
>>>
>>> I am trying to use the ksmeta="" construct to pass a list of
>>> dictionaries through to the kickstart file where I am using a cheetah
>>> "#for $var in $vars" loop to unravel them.
>>>
>>> Is this possible?
>>>       
>> Achieving that result is possible, though as you've entered it, the
>> variable will just be a string, not a data structure.    --ksmeta in the
>> command line allows for "key=value key=value" ... key/value pairs
>> seperated by spaces.   Those values aren't evaluated to be Python data
>> structures.
>>
>> I have not really used Cheetah for ultra-advanced templating usage,
>> though it does allow executing arbitrary python code, so in theory,
>> you could pass in arbitrary strings and work on them in Python,
>> including evaling them to create real data structures.   Whether this
>> works
>> as advertised I don't know... though I could definitely use some more
>> advanced templating examples for the Wiki.
>>
>> I'd be inclined to take a simpler approach though, and pass in simple
>> variables like --ksmeta="eth0=dhcp eth1=dhcp", and then check
>> for the values of those expressions, possibly in conjunction with "#if"
>> templating
>>
>> #if defined $eth0   # syntax for this is probably wrong :)
>>
>>     some line containing value for $eth0
>> #end
>>
>> etc
>>     
>
> I spent some time working with this today.
>
> Cheetah allows you to use #if $variable as a shortcut for "is the variable
> defined?"
>
> This shortcut will not work with Cobbler.  If something like that is
> written in a kickstart template, and the profile with which it is
> associated doesn't have the variable in its ksmeta, cobbler sync will
> crash.
>   
Interesting... I'll take a look at this.   There may be a workaround in 
the way we are using the Cheetah API.

> There's a workaround.
>
> Instead of using the shortcut to see if the variable is defined, define it
> to "none" or something obviously wrong/null in the profile.
>
> For example, we have default printer information stored in Cobbler.  If we
> set the profile to have the ksmeta pair of DefaultPrinter=none, our
> kickstart template can have the section
>
> #if $DefaultPrinter != "none"
> lpoptions -d $DefaultPrinter
> #end if
>
> It works, and is only slightly less elegant than the (not working)
>
> #if $DefaultPrinter
> lpoptions -d $DefaultPrinter
> #end if
>
> I'm running the git sources from 2 days ago, if it matters to anyone.
>
> Adam Wolf
>
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