how do i override/redefine a resource that is declared in another class?

[mark]

hi all,
newbie here...

i've been fiddling around with the inherits form...but..i can't seem
to get any headway out of it.
i've been googling and looking at some docs, but i think i might still
be confused as to how things work.
- what i've found seems to talk about overrinding variables $variable,
but..i'm trying to change a resource/service is this completely
different?
- the docs i see refer to class names as simple words like "class
snoopy", but everywhere i see classes here are of the form
snoopy::lucy...

anyway from what i can find from the error message, it doesn't like
that in my manifest file (node mynode { ... }) has a stanza:
service { netfs:
stuff=>data
stuff=>data
...
}
it says netfs is already defined.

so i looked around and it appears that my manifest file has an
include: example "include base::services"
the file it's loading also has an include that calls another file,
and THAT file has some classes in it..one of which has a netfs stanza
like above. i want to override that
in my manifest/node file. however i can't change anything anywhere
except in my manifest/node file.

one solution i know will work is to replace my first include with the
actual file itself, and replace the 2nd
include with the huge class file and change the class manually. but
expanding everything doesn't seem like it would be the suave way to go
in any complex setup. it'd be nice to be able to say: do this, except
for this.

my fear was that maybe the 'except for' method might be frowned upon
too as too 'goto' like and kludgy in nature?

hopefully the solution is simple and i'm just not getting the syntax
right..

any advice would be appreciated!

thanks much,
mark

[Peter Meier]

Hi

> i've been fiddling around with the inherits form...but..i can't seem
> to get any headway out of it.

What is your problem with inheritance? Maybe we can give you a way out
and following example shows you that it is the way to go:

$ cat foo.pp
class a {
file{'/tmp/a': ensure => file}
file{'/tmp/b': ensure => file}
}

class b inherits a {
File['/tmp/b']{ensure => absent }
}

include a
include b
$ puppet foo.pp
notice: //a/File[/tmp/a]/ensure: created
$

you can include the inherited class anywhere you'd like to. So for
example simply write disable classes for the services you don't want
to manage on certain nodes and then include these in your node.

cheers pete

[mark]

back on my own account again, updating:
hi! thanks for the advice
i think i don't understand the nature of 'include'. in my mind include
is something that is invisible to the actual engine that does
things..it's a shorthand

that replaces 'include X' with the contents of X and then the software
goes to work on the final result and humans don't have to look at
hugely long files.

so when i see a file that says

class A {

blah

}

include A



it seems like it's redundant...so i'm thinking in the puppet
world..does include have some stronger meaning like "and execute the
code"?



here is the specifics of my multilayer include world:

------------------------------------------------------

my attempt to trace the lineage of the resource i'm bumping into

in my manifest/node file:

node "chquoteq02.tradearca.com" {

...

include base::setup

...

i'd like to TURN ON SERVICE netfs for this node



}

------------------------------------------------------

in /etc/puppet/modules-base/trunk/base/manifests/init.pp:



class base::setup {

...

include services::setup

...

}

------------------------------------------------------

in /etc/puppet/modules-base/trunk/services/manifests/init.pp:



class services::setup {

...

include services::base

...

}



class services::base {

...

service { netfs:

... TURNS OFF SERVICE

}

...

}







so give this, i tried this (but it didn't work) in my manifest/node
file:

class myoverrideclass inherits services::base {

service { netfs:

enable => true,

ensure => running,

hasstatus => true,

}

}



include base::setup

include myoverrideclass



i ran: puppetd -ov --no-daemonize

on the client server and got:

err: Could not retrieve catalog: Puppet::Parser::AST::Resource failed
with error ArgumentError: Duplicate definition: Service[netfs] is
already defined in file /etc/puppet/modules-base/trunk/services/
manifests/init.pp at line 385; cannot redefine at /etc/puppet/
manifests/nodes/chquoteq02.tradearca.com.node:491 on node
chquoteq02.tradearca.com



i even tried moving the 'include base::setup' to be above the
'myoverrideclass' definition but still the same problem...

[Silviu Paragina]

On 26.11.2009 16:48, mark wrote:
> back on my own account again, updating:
> hi! thanks for the advice
> i think i don't understand the nature of 'include'. in my mind include
> is something that is invisible to the actual engine that does
> things..it's a shorthand
>
> that replaces 'include X' with the contents of X and then the software
> goes to work on the final result and humans don't have to look at
> hugely long files.
>

no, not by far.
Include has the meaning, make sure that the rules in the specified class
are also applied. Multiple includes of the same class from different
places will apply the class only once.
Require (>=0.25, hope this is what is called never actually used it :">
) is similar, with the sole exception that it makes sure that the
definitions in the specified class are applied before the definitions in
your class.
Also note that there is no particular order in which your definitions
are applied. When you use before it just means that the current resource
will be applied before the other resource, but 1000 other resources
could be applied in between.(same goes for require)

> so when i see a file that says
>
> class A {
>
> blah
>
> }
>
> include A
>
>
>
> it seems like it's redundant...so i'm thinking in the puppet
> world..does include have some stronger meaning like "and execute the
> code"?
>
>

You should think at it more of a description, not code. (like you would
in any other descriptive language)

Service with "S" not "s". When the first letter is uppercase the
statement alters an already existing definition, when it's lower case
it's a new definition. Here:
http://reductivelabs.com/trac/puppet/wiki/LanguageTutorial#classes .

>
>
> include base::setup
>
> include myoverrideclass
>
>
>
> i ran: puppetd -ov --no-daemonize
>

I prefer puppetd --test (faster to write and not too verbose)

> --
>
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>
>
>
Good luck and welcome to puppet,
Silviu

[mark inaba]

thanks so much to peter meier and silviu paragina for their assistance.
i didn't realize i needed the capital S in Service and the slightly different
format in changing the value of the service resource than when first
creating it.
i wanted to test it to make sure it worked, and it did!

thanks so much again :)

-mark