cleanup pref_challs help, use consistent naming, and simplify parsing

certbot/cli.py

@@ -11,10 +11,10 @@ import sys
 import configargparse
 import six
 
-import certbot
-
 from acme import challenges
 
+import certbot
+
 from certbot import constants
 from certbot import crypto_util
 from certbot import errors
@@ -847,12 +847,13 @@ def prepare_and_parse_args(plugins, args, detect_defaults=False):  # pylint: dis
         help="Require that all configuration files are owned by the current "
              "user; only needed if your config is somewhere unsafe like /tmp/")
     helpful.add(
-        "security", "--preferred-challenges", dest="pref_chall",
-        action=_PrefChallAction, default=[],
-        help="Specify which challenges you'd prefer to use. If any of those "
-             "challenges are valid for your authenticator they will be used. "
-             "Otherwise Certbot will not attempt authorization. The first "
-             "challenge listed that is supported by the plugin will be used.")
+        ["certonly", "renew", "run"], "--preferred-challenges",
+        dest="pref_challs", action=_PrefChallAction, default=[],
+        help="A sorted, comma delimited list of the preferred challenge to "
+             "use during authorization with the most preferred challenge "
+             "listed first (e.g. tls-sni-01,http-01). If none of the "
+             "preferred challenges can be used by the selected plugin to "
+             "satisfy the CA, authorization is not attempted.")
     helpful.add(
         "renew", "--pre-hook",
         help="Command to be run in a shell before obtaining any certificates."
@@ -1045,30 +1046,12 @@ def add_domains(args_or_config, domains):
 class _PrefChallAction(argparse.Action):
     """Action class for parsing preferred challenges."""
 
-    def __call__(self, parser, namespace, pref_chall, option_string=None):
-        """Just wrap add_pref_challs in argparseese."""
-        _ = add_pref_challs(namespace, pref_chall)
-
-def add_pref_challs(namespace, pref_challs):
-    """Parses and validates user specified challenge types.
-
-    Adds challenges (in order) to the configuration object.
-
-    :param namespace: parsed command line arguments
-    :type namespace: argparse.Namespace or
-        configuration.NamespaceConfig
-    :param str pref_challs: one or more comma separated challenge types
-
-    :returns: Challenge objects which match the validated string inputs
-    :rtype: `list`
-    """
+    def __call__(self, parser, namespace, pref_challs, option_string=None):
         challs = pref_challs.split(",")
-    unrecognized = [name for name in challs if name not in challenges.Challenge.TYPES]
+        unrecognized = ", ".join(name for name in challs
+                                 if name not in challenges.Challenge.TYPES)
         if unrecognized:
             raise argparse.ArgumentTypeError(
-                "Unrecognized challenges: {0}".format(", ".join(unrecognized)))
-
-    out = [challenges.Challenge.TYPES[name] for name in challs]
-    print(namespace)
-    namespace.pref_chall.extend(out)
-    return out
+                "Unrecognized challenges: {0}".format(unrecognized))
+        namespace.pref_challs.extend(challenges.Challenge.TYPES[name]
+                                     for name in challs)

certbot/client.py

@@ -192,7 +192,7 @@ class Client(object):
 
         if auth is not None:
             self.auth_handler = auth_handler.AuthHandler(
-                auth, self.acme, self.account, self.config.pref_chall)
+                auth, self.acme, self.account, self.config.pref_challs)
         else:
             self.auth_handler = None