Community.Dns Filter Guide

The community.dns collection offers several filters for working with DNS names:

These filters allow to work with public suffixes; a public suffix is a DNS suffix under which users can (or could) directly register names. They use the Public Suffix List, a Mozilla initiative maintained as a community resource which tries to list all such public suffixes. Common examples for public suffixes are .com, .net, but also longer suffixes such as .co.uk or .github.io.

The label directly before the public suffix together with the suffix is called the registrable domain name or registered domain name, since these are usually the names that people can register. Examples for registrable domain names are example.com and example.co.uk, while www.example.com is not a registrable domain name. A public suffix itself is also not a registrable domain name, as for example github.io.

Working with public suffixes

The community.dns.get_public_suffix and community.dns.remove_public_suffix filters allow to extract and remove public suffixes from DNS names:

- assert:
    that:
      - >-
        "www.ansible.com" | community.dns.get_public_suffix == ".com"
      - >-
        "some.random.prefixes.ansible.co.uk" | community.dns.get_public_suffix == ".co.uk"
      - >-
        "www.ansible.com" | community.dns.remove_public_suffix == "www.ansible"
      - >-
        "some.random.prefixes.ansible.co.uk" | community.dns.remove_public_suffix == "some.random.prefixes.ansible"

The filters also allow additional options (keyword arguments):

keep_unknown_suffix

A boolean with default value true. This treats unknown TLDs as valid public suffixes. So for example the public suffix of example.tlddoesnotexist is .tlddoesnotexist if this is true. If set to false, it will return an empty string in this case. This option corresponds to whether the global wildcard rule * in the Public Suffix List is used or not.

icann_only

A boolean with default value false. This controls whether only entries from the ICANN section of the Public Suffix List are used, or also entries from the Private section. For example, .co.uk is in the ICANN section, but github.io is in the Private section.

normalize_result

(Only for community.dns.get_public_suffix) A boolean with default value false. This controls whether the result is reconstructed from the normalized name used during lookup. During normalization, ulabels are converted to alabels, and every label is converted to lowercase. For example, the ulabel ëçãmplê is converted to xn--mpl-llatwb (puny-code), and Example.COM is converted to example.com.

keep_leading_period

(Only for community.dns.get_public_suffix) A boolean with default value true. This controls whether the leading period of a public suffix is preserved or not.

keep_trailing_period

(Only for community.dns.remove_public_suffix) A boolean with default value false. This controls whether the trailing period of the prefix (that is, the part before the public suffix) is preserved or not.

Working with registrable domain names

The community.dns.get_registrable_domain and community.dns.remove_registrable_domain filters allow to extract and remove registrable domain names from DNS names:

- assert:
    that:
      - >-
        "www.ansible.com" | community.dns.get_registrable_domain == "ansible.com"
      - >-
        "some.random.prefixes.ansible.co.uk" | community.dns.get_registrable_domain == "ansible.co.uk"
      - >-
        "www.ansible.com" | community.dns.remove_registrable_domain == "www"
      - >-
        "some.random.prefixes.ansible.co.uk" | community.dns.remove_registrable_domain == "some.random.prefixes"

The filters also allow additional options (keyword arguments):

keep_unknown_suffix

A boolean with default value true. This treats unknown TLDs as valid public suffixes. So for example the public suffix of example.tlddoesnotexist is .tlddoesnotexist if this is true, and hence the registrable domain of www.example.tlddoesnotexist is example.tlddoesnotexist. If set to false, the registrable domain of www.example.tlddoesnotexist is tlddoesnotexist. This option corresponds to whether the global wildcard rule * in the Public Suffix List is used or not.

icann_only

A boolean with default value false. This controls whether only entries from the ICANN section of the Public Suffix List are used, or also entries from the Private section. For example, .co.uk is in the ICANN section, but github.io is in the Private section.

only_if_registerable

A boolean with default value true. This controls the behavior in case there is no label in front of the public suffix. This is the case if the DNS name itself is a public suffix. If set to false, in this case the public suffix is treated as a registrable domain. If set to true (default), the registrable domain of a public suffix is interpreted as an empty string.

normalize_result

(Only for community.dns.get_registrable_domain) A boolean with default value false. This controls whether the result is reconstructed from the normalized name used during lookup. During normalization, ulabels are converted to alabels, and every label is converted to lowercase. For example, the ulabel ëçãmplê is converted to xn--mpl-llatwb (puny-code), and Example.COM is converted to example.com.

keep_trailing_period

(Only for community.dns.remove_registrable_domain) A boolean with default value false. This controls whether the trailing period of the prefix (that is, the part before the registrable domain) is preserved or not.