Writing Hiera data

As we've seen, Hiera data is stored in text files that are structured using the format called YAML (short for YAML Ain't Markup Language), which is a common way of organizing data. Here's another snippet from our sample Hiera data file (hiera_sample.yaml):

---
  ...
  syslog_server: '10.170.81.32'
  monitor_ips:
    - '10.179.203.46'
    - '212.100.235.160'
    - '10.181.120.77'
    - '94.236.56.148'
  cobbler_config:
    manage_dhcp: 1
    pxe_just_once: 1

There are actually three different kinds of Hiera data structures present: single values, arrays, and hashes. We'll examine these in detail in a moment.

File header

YAML files begin, like the previous example, with three dashes and a newline (---). This is part of the YAML format, not a Hiera feature; it's the syntax indicating the start of a new YAML document.

Single values

Most Hiera data consists of a key associated with a single value, as in the previous example:

syslog_server: '10.170.81.32'

The value can be any legal...