Resolution: Won't Do
Affects Version/s: HI 3.2.1
Fix Version/s: None
QA Risk Assessment:Needs Assessment
In older versions of Hiera you could use a nil in the backend to force the Hiera default to be selected.
For example, given the simple Hierarchy:
And data/common with:
my_var: 'global val'
You could use in data/host:
And Hiera would return the specified default value back to Puppet. This would allow the intentional "unsetting" of a particular key in Hiera for a small set of hosts that otherwise received more global Hiera-based settings.
This used to work in Hiera and was usable from Puppet with hiera('my_key', 'a default')
Now, Hiera (arguably more correctly) returns the found value nil, but Puppet doesn't fall back to the default, it instead raises an error and aborts the catalog compilation.
This breaks a small but important bit of flexibility in Hiera.