module

Krikri::PluginHelpers::Getfqdn

socket.getfqdn() emulation for the hostname plugin's returned facts.

The reason this is NOT a hostname -f call: Python's socket.getfqdn() forward-resolves the name to an address and then REVERSE-resolves that address, so the answer reflects what NSS (/etc/hosts, DNS) says about the address, not the machine's own view of its name; hostname -f is a forward lookup of the queried name and echoes that view back. The two diverge exactly when a role colocates its hostname on the 127.0.0.1 /etc/hosts line (oasis_roles.hostname's pattern, issue #585): real ansible-playbook then reports ansible_fqdn as "localhost"/"localhost.localdomain" and keeps re-reporting changed, while a hostname -f-based value stays at the short name and makes krikri falsely idempotent there.

getent reads the same NSS sources Python's socket module does, without assuming python3 exists on the managed node.

Class methods

from_getent_hosts(output : String) : String

socket.getfqdn()'s final step over one getent hosts <ip> line ("<ip> <canonical> [alias ...]"): the canonical name is checked first (Python's aliases.insert(0, hostname)), then the aliases in order, and the first entry containing a dot wins.

When every name on the line is dotless, CPython's name = hostname branch returns the reverse lookup's own canonical name - NOT the machine's current hostname: a role can add a line like 127.0.1.1 testhost <machine-name> whose canonical name ("testhost") is unrelated to the machine name, and ansible-playbook then reports ansible_fqdn = "testhost". A System.hostname fallback instead would report the machine name and keep a later hostname: name={{ ansible_fqdn }} task ok where ansible reports changed every run. "" stays reserved for a line with no name field at all (gethostbyaddr failing), which the caller maps to its fallback.

Source

lookup(name : String) : String

CPython's socket.getfqdn(name): forward-resolve the name to an address, then reverse-resolve that address and parse the reverse line. When gethostbyaddr fails, CPython returns the queried name itself - that fallback belongs to the caller; "" here only means "no usable resolver answer", so the caller can tell the two cases apart.

Source