feat(inventory): connect via public ipv6 address (#176)

Add a new `connect_with` option `public_ipv6` that uses the first
address from the servers publically-routed ipv6 network.

changelogs/fragments/inventory-connect-via-ipv6.yml

@@ -0,0 +1,4 @@
+minor_changes:
+  - inventory plugin - Add new connect_with setting public_ipv6 to connect to discovered servers via public IPv6 address.
+breaking_changes:
+  - inventory plugin - Python v3.5+ is now required.

plugins/inventory/hcloud.py

@@ -11,7 +11,7 @@ DOCUMENTATION = r'''
       - Lukas Kaemmerling (@lkaemmerling)
     short_description: Ansible dynamic inventory plugin for the Hetzner Cloud.
     requirements:
-        - python >= 2.7
+        - python >= 3.5
         - hcloud-python >= 1.0.0
     description:
         - Reads inventories from the Hetzner Cloud API.
@@ -42,6 +42,7 @@ DOCUMENTATION = r'''
             type: str
             choices:
                 - public_ipv4
+                - public_ipv6
                 - hostname
                 - ipv4_dns_ptr
                 - private_ipv4
@@ -113,6 +114,7 @@ from ansible.errors import AnsibleError
 from ansible.module_utils._text import to_native
 from ansible.plugins.inventory import BaseInventoryPlugin, Constructable
 from ansible.release import __version__
+from ipaddress import IPv6Network
 
 try:
     from hcloud import hcloud
@@ -222,6 +224,8 @@ class InventoryModule(BaseInventoryPlugin, Constructable):
 
         if self.get_option("connect_with") == "public_ipv4":
             self.inventory.set_variable(server.name, "ansible_host", to_native(server.public_net.ipv4.ip))
+        if self.get_option("connect_with") == "public_ipv6":
+            self.inventory.set_variable(server.name, "ansible_host", to_native(self._first_ipv6_address(server.public_net.ipv6.ip)))
         elif self.get_option("connect_with") == "hostname":
             self.inventory.set_variable(server.name, "ansible_host", to_native(server.name))
         elif self.get_option("connect_with") == "ipv4_dns_ptr":
@@ -259,6 +263,9 @@ class InventoryModule(BaseInventoryPlugin, Constructable):
         # Labels
         self.inventory.set_variable(server.name, "labels", dict(server.labels))
 
+    def _first_ipv6_address(self, network):
+        return next(IPv6Network(network).hosts())
+
     def verify_file(self, path):
         """Return the possibly of a file being consumable by this plugin."""
         return (