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What's the best pattern to use a deeper hiera merge and get around automatic parameter lookup limitations?

asked 2015-06-19 15:11:54 -0600

rnelson0 gravatar image

As described at the bottom of the hiera lookup types page, there is a significant limitation with merge behavior: automatic parameter lookup will always perform a native lookup even if the :merge_behavior is deep or deeper (the older redmine ticket leads to HI-118 in Jira). This prevents me from relying on deeper merge to define mysql::server::override_options in two files, one at my puppet_role hierarchy level and additional values related to replication in the clientcert hierarchy. For instance:

# Simplified - there are close to a dozen values in reality
mysql::server::override_options :
    bind-address             : ''

    server-id                : 1
    auto-increment-increment : 2
    auto-increment-offset    : 1

This generates two vastly different results based on whether hiera is called with or without a hash lookup (APL does lookups without):

# Without hash
$ sudo hiera mysql::server::override_options environment=mysql puppet_role=mysql clientcert=hostname
  {"server-id"=>1, "auto-increment-increment"=>2, "auto-increment-offset"=>1}}

# With hash
$ sudo hiera -h mysql::server::override_options environment=mysql puppet_role=mysql clientcert=hostname
  {"bind-address"=>"", "server-id"=>1, "auto-increment-increment"=>2, "auto-increment-offset"=>1}}

This presents a problem as my profile class is pretty simple:

class profile::mysql::server{
  # SELinux stuff
  # Firewall rule

  include ::mysql::server
  include ::mysql::server::backup
  include ::mysql::server::account_security

I rely on APL to provide the values I need to the class without specifying them via a lookup. I believe that I can replace the top include with:

class {'::mysql::server':
  override_options = hiera_hash('profile::mysql::server::override_options'),   # with resultant changes to hiera yaml

Any other class parameters should still be filled by APL per the documentation. I have two questions:

  1. Is my reading of the documentation correct, that parameters not provided in the resource declaration will be filled in by APL?
  2. Is this a good pattern? Before I rewrite the structure of the profile and get 6 months down the road, I'd like to know if there are any known issues with this pattern or other suggested patterns to use instead.


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answered 2015-06-19 15:41:26 -0600

WhatsARanjit gravatar image

You'll want to wrap the hiera_hash function into a profile:

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Asked: 2015-06-19 15:11:54 -0600

Seen: 1,568 times

Last updated: Jun 19 '15