Hi,
I use Puppet 3.2 with Hiera. I would like to know the best practices
when you want to share one data between 2 classes or modules.
I take an example. I have:
- One "snmp" module which installs and configures snmpd in the hosts.
In this module, I must define the community password.
- One "monitoring" module which installs and configures any monitoring
software (by example Nagios if you want, it doesn't matter). In this module,
I must define too the community password in order to the software monitoring
runs valid snmp requests.
So, the "snmp" module and the "monitoring" module must share the same
data: the community password. Which are the best practice to do this?
Firstly, I see this way.
In the /etc/puppet/hieradata/default.yaml, I have this:
---
snmp:
community: abcd1234
monitoring:
community: abcd1234
Then, in my "snmp" class, I have this:
class snmp {
$snmp = hiera_hash('snmp')
$community = $snmp['community']
# and the rest of the class...
}
And in my "monitoring" class, I have this:
class monitoring {
$monitoring = hiera_hash('monitoring')
$community = $monitoring['community']
# and the rest of the class...
}
Like this, my modules are independent but the same "community password"
data is duplicated in 2 different places. Ok, in my example, the data
is in the same file (default.yaml) but we can imagine more complex cases
where the same data is duplicated in 2 different files (because the data
hierarchy isn't limited to one "default.yaml" file etc).
Secondly, I see this way.
In the /etc/puppet/hieradata/default.yaml, I have this:
---
# The "community" key is present just in one place and that's all.
snmp:
community: abcd1234
# No "community" key in monitoring.
monitoring:
# some keys but not the "community" key.
contacts:
- john
- herbert
Then, in my "snmp" module, I have the snmp::params class which
just contains variables assignments:
class snmp::params {
$snmp = hiera_hash('snmp')
$community = $snmp['community']
# and the rest of the class...
}
class snmp {
include snmp::params
# and the rest of the class...
# we can use the $snmp::params::community variable.
}
And in my "monitoring" class, I have this:
class monitoring {
include snmp::params
$community = $snmp::params::community
# and the rest of the class...
}
Now, the "community password" data isn't duplicated, but my modules
aren't independent because the "monitoring" module depends on the
"snmp" module. And I suppose that's better to have independent modules.
So, what are the best practices to share the "community password"
between the "snmp" module and the "monitoring" module?
Thanks in advance for your help.
--
François Lafont
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