Only *master* zones need zone files pre-populated, as the other types of
zones are populated by data named receives from queries and transfers.
Other types of zones require other options, however, to be usable. This
commit introduces minimal support for specifying *slave*, *forward*, and
*stub* zones.
Items in the `allow_update` property can use the address match list
syntax to specify arbitrary restrictions, including TSIG key names.
There is really no need for a special case for key names.
The *named* role now supports generating configuration for authoritative
DNS zones and DNSSEC keys. Zones are defined by populating the
`named_zones` variable with a list of objects describing the zone. Zone
properties can include:
* `name`: The DNS domain name
* `type`: The zone type, defaults to `master`
* `allow_update`: A list of hosts/networks or DNSSEC key names (which
must be specified as an object with a `key` property)
* `update_policy`: A list of BIND update policy statements
* `ttl`: The default (minimum) TTL for the zone
* `origin`: The authoritative name server for the zone
* `refresh`, `retry`, `expire`: Record cache timeout values
* `default_records`: A list of default records, defined as objects with
the following properties:
* `name`: The RR name
* `type`: The RR type (default: `A`)
* `value`: The RR value
Zone files will be created in `/var/named/dynamic`. Existing zone files
will **not** be overwritten; management of zone records is done using
`nsupdate` or similar.