Changing namevar of resources triggering alias error

[Luke Bigum]

Can someone explain this to me? I thought I'd be able to change the title of a nagios_host resource but leave name_var the same to effectively write two nagios_host files to disk with the same content, but instead I'm triggering an error in the resouce alias code. I didn't realise changing namevar was using resource aliases under the hood?

Any ideas on how I could make this work?


[root@localhost ~]# cat test.pp
nagios_host { 'foo':
ensure => present,
host_name => 'foo',
address => 'foo',
target => '/tmp/foo',
}

nagios_host { 'foo_again':
ensure => present,
host_name => 'foo',
address => 'foo',
target => '/tmp/foo_again',
}
[root@localhost ~]#
[root@localhost ~]#
[root@localhost ~]# puppet apply test.pp
Notice: Compiled catalog for localhost in environment production in 0.10 seconds
Error: Cannot alias Nagios_host[foo_again] to ["foo"] at /root/test.pp:13; resource ["Nagios_host", "foo"] already declared at /root/test.pp:6



--
Luke Bigum
Senior Systems Engineer

Information Systems
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[Craig Dunn]

On Fri, Jul 29, 2016 at 5:53 PM, Luke Bigum <luke....@lmax.com> wrote:

Can someone explain this to me? I thought I'd be able to change the title of a nagios_host resource but leave name_var the same to effectively write two nagios_host files to disk with the same content, but instead I'm triggering an error in the resouce alias code. I didn't realise changing namevar was using resource aliases under the hood?

Short answer here is, you can't - at least without modifying the nagios_host type.   Puppet defines uniqueness by the value of the namevar, in the absence of the namevar being defined, it's value is set from the resource title.   Therefore you can never have two resources with the same namevar.

The theoretical solution to your issue would be to make a composite namevar combining both the target and the host_name - I did an extensive write up of all this recently; 

http://www.craigdunn.org/2016/07/composite-namevars-in-puppet/

One slightly hackish approach would be to write your own custom_nagios_host type using composite namevars and write a small provider that doesn't do much else than inherit off the nagios_host default provider.

--
Luke Bigum
Senior Systems Engineer

[ massive snip ]

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