install: introduce installer class hierarchy

Add class hierarchy which allows inherting knob definitions between the
various client and server install scripts.

https://fedorahosted.org/freeipa/ticket/6392

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipalib/install/hostname.py

@@ -0,0 +1,59 @@
+#
+# Copyright (C) 2016  FreeIPA Contributors see COPYING for license
+#
+
+"""
+Host name installer module
+"""
+
+from ipapython.install import typing
+from ipapython.install.core import knob
+from ipapython.ipautil import CheckedIPAddress
+
+from . import service
+from .service import prepare_only
+
+
+class HostNameInstallInterface(service.ServiceInstallInterface):
+    """
+    Interface common to all service installers which create DNS address
+    records for `host_name`
+    """
+
+    ip_addresses = knob(
+        # pylint: disable=invalid-sequence-index
+        typing.List[CheckedIPAddress], None,
+        description="Specify IP address that should be added to DNS. This "
+                    "option can be used multiple times",
+        cli_names='--ip-address',
+        cli_metavar='IP_ADDRESS',
+    )
+    ip_addresses = prepare_only(ip_addresses)
+
+    @ip_addresses.validator
+    def ip_addresses(self, values):
+        for value in values:
+            try:
+                CheckedIPAddress(value, match_local=True)
+            except Exception as e:
+                raise ValueError("invalid IP address {0}: {1}".format(
+                    value, e))
+
+    all_ip_addresses = knob(
+        None,
+        description="All routable IP addresses configured on any inteface "
+                    "will be added to DNS",
+    )
+    all_ip_addresses = prepare_only(all_ip_addresses)
+
+    no_host_dns = knob(
+        None,
+        description="Do not use DNS for hostname lookup during installation",
+    )
+    no_host_dns = prepare_only(no_host_dns)
+
+    no_wait_for_dns = knob(
+        None,
+        description="do not wait until the host is resolvable in DNS",
+    )
+    no_wait_for_dns = prepare_only(no_wait_for_dns)