Using Hiera in Puppet

The data stored in Hiera can be retrieved by the Puppet Master while compiling the catalog using the Hiera functions. In our manifests, we can have something like the following:

$dns_servers = hiera("dns_servers")

Note that the name of the Puppet variable need not be the same as the Hiera one, so the preceding command can also be something like this:

$my_dns_servers = hiera("dns_servers")

This assigns the top value to the $my_dns_servers variable (the first one found while crossing the hierarchy of data sources) retrieved by Hiera for the key dns_servers.

We can also merge arrays and hashes here, so, in order to retrieve an array of all the values in the hierarchy's data sources of a given key and not just the first one, we can ...

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