How to reference a hiera variable from elsewhere the hierarchy?

Question

So suppose in a very specific hiera YAML file I define a variable, such as "env_name".

env_name: "dev-unstable"

Now in a more general hiera file I'd like to interpolate that variable into a string.

server_name: "service-%{env_name}.%{::domain}"

My testing seems to imply that hiera variables from elsewhere in the hierarchy aren't made available for interpolation in general cases. Is that true, unfortunately?

Answer 1

You can use Hiera lookup functions within Hiera. Documentation here: https://docs.puppetlabs.com/hiera/1/variables.html#using-lookup-functions

In your case you would use:

server_name: "service-%{hiera('env_name')}.%{::domain}"

This is a priority lookup and will get the value for the key env_name from the highest (most specific) hierarchy level in which it finds the key.

This requires Hiera 1.3 or higher.

Answer 2

For Hiera 5, used in Puppet 5+, use the following syntax:

server_name: "service-%{lookup('env_name')}.%{::domain}"

...where %{lookup('env_name')} is the part that gets the data from the other hiera key, env_name.

(Source)

Answer 3

See the answer from Greg Dubicki.

To quote "The hiera, hiera_array, hiera_hash, and hiera_include functions are all deprecated. The lookup function is a complete replacement for all of these."

For details see:

https://puppet.com/docs/puppet/5.5/hiera_migrate.html#updated_classic_hiera_function_calls