Set the merge behavior for a lookup

When you look up a key in Hiera, it is common for multiple data sources to have different values for it. By default, Hiera returns the first value it finds, but it can also continue searching and merge all the found values together.

1. You can set the merge behavior for a lookup in two ways:
   • At lookup time. This works with the lookup function, but does not support automatic class parameter lookup.
   • In Hiera data, with the lookup_options key. This works for both manual and automatic lookups. It also lets module authors set default behavior that users can override.
2. With both of these methods, specify a merge behavior as either a string, for example, 'first' or a hash, for example {'strategy' => 'first'}. The hash syntax is useful for deep merges (where extra options are available), but it also works with the other merge types.

Related information

• The Puppet lookup function