The dedicated folder where hiera will store the files hierarchy is called hieradata and is located in the same folder as the projects folder. Currently this folder name cannot be customised.

If hiera.yaml has been customised the files structure needs to match that configuration.

The variables use to query hiera are:

• project (-p)
• application (-a)
• environment (-e)
• location (-l)
• any mappings created using the extra/mappings/* folder will be passed to hiera

Variables

The variable format is %{VARIABLE default “DEFAULT_VALUE”} or %{VARIABLE}.
The variable priority order is:

• -x variables (cmd argument)
• hiera
• default value specified as part of variable template

The value before “default” (in the above example “VARIABLE”) will be retrieved from hiera. If no value is available in hiera the value after “default” (in the above example “DEFAULT_VALUE”) will be used as default.

There are few types of variables supported:

• single value variables which can be declared using -x argument, from hiera or template default
• multi line variables (only for yaml template). These are handy for all kind of headers, metadata values or any other data difference between deployments which has more than a single value.
  Example:
  Instead of having in each template the kind and API version the configs can be extracted to variables in common.yaml

    kind: ReplicationController
    apiVersion: v1
  

  will become

    %{kind_replication}
  

  and the common.yaml will look like below

    kind_replication:
        kind: ReplicationController
        apiVersion: v1
  

• encrypted variables using eyaml
• composed variables. A single variable can have multiple values collected from hierarchy. explanation