Use f-strings in many places in acme and certbot. (#9225)

acme/acme/challenges.py

@@ -279,7 +279,7 @@ class DNS01(KeyAuthorizationChallenge):
         :rtype: str
 
         """
-        return "{0}.{1}".format(self.LABEL, name)
+        return f"{self.LABEL}.{name}"
 
 
 @ChallengeResponse.register

acme/acme/client.py

@@ -1142,8 +1142,7 @@ class ClientNetwork:
                     'response', response_ct)
 
             if content_type == cls.JSON_CONTENT_TYPE and jobj is None:
-                raise errors.ClientError(
-                    'Unexpected response Content-Type: {0}'.format(response_ct))
+                raise errors.ClientError(f'Unexpected response Content-Type: {response_ct}')
 
         return response
 
@@ -1196,7 +1195,7 @@ class ClientNetwork:
             if m is None:
                 raise  # pragma: no cover
             host, path, _err_no, err_msg = m.groups()
-            raise ValueError("Requesting {0}{1}:{2}".format(host, path, err_msg))
+            raise ValueError(f"Requesting {host}{path}:{err_msg}")
 
         # If the Content-Type is DER or an Accept header was sent in the
         # request, the response may not be UTF-8 encoded. In this case, we

acme/acme/messages.py

@@ -157,12 +157,11 @@ class _Constant(jose.JSONDeSerializable, Hashable):
     @classmethod
     def from_json(cls, jobj: str) -> '_Constant':
         if jobj not in cls.POSSIBLE_NAMES:  # pylint: disable=unsupported-membership-test
-            raise jose.DeserializationError(
-                '{0} not recognized'.format(cls.__name__))
+            raise jose.DeserializationError(f'{cls.__name__} not recognized')
         return cls.POSSIBLE_NAMES[jobj]
 
     def __repr__(self) -> str:
-        return '{0}({1})'.format(self.__class__.__name__, self.name)
+        return f'{self.__class__.__name__}({self.name})'
 
     def __eq__(self, other: Any) -> bool:
         return isinstance(other, type(self)) and other.name == self.name

acme/acme/mixins.py

@@ -65,4 +65,4 @@ def _safe_jobj_compliance(instance: Any, jobj_method: str,
             jobj.pop(uncompliant_field, None)
         return jobj
 
-    raise AttributeError('Method {0}() is not implemented.'.format(jobj_method))  # pragma: no cover
+    raise AttributeError(f'Method {jobj_method}() is not implemented.')  # pragma: no cover