Can't specify hiera::hierarchy in hiera

[westbywest]

Having the default value for the "hierarchy" parameter specified as [], i.e. an empty array, prevents one from providing the value of this parameter via hiera. You need to leave a default parameter value as undef for Puppet to do automatic parameter lookup.

https://docs.puppetlabs.com/hiera/3.0/puppet.html#automatic-parameter-lookup

[jyaworski]

Can you give an example of this failing?

[westbywest]

Yes. Defining this array in hiera:

hiera::hierarchy:
  - "%{environment}/%{calling_class}"
  - "%{environment}"
  - common

... and then invoking the hiera class with expectation of it picking up the "hierarchy" parameter automatically from hiera fails:

class { 'hiera': }

The class uses '[]' for the parameter value. Specifying a default empty array in code overrides Puppet's automated parameter lookup from hiera, as that lookup only does native merging and not deep merging.

The work-around I have to do is wrap hiera::init in a another class (i.e. a profile class) and do the hiera lookup of "hiera::hierarchy" explicitly.

$hierarchy_real = hiera("hiera::hierarchy", undef)
class { 'hiera':
  hierarchy => hierarchy_real,
}

[hunner]

Merged in #119