Add API version and have server reject incompatible clients.

This patch contains 2 parts.

The first part is a small utility to create and validate the current
API. To do this it needs to load ipalib which on a fresh system
introduces a few problems, namely that it relies on a python plugin
to set the default encoding to utf8. For our purposes we can skip that.
It is also important that any optional plugins be loadable so the
API can be examined.

The second part is a version exchange between the client and server.
The version has a major and a minor version. The major verion is
updated whenever existing API changes. The minor version is updated when
new API is added. A request will be rejected if either the major versions
don't match or if the client major version is higher than then server
major version (though by implication new API would return a command not
found if allowed to proceed).

To determine the API version of the server from a client use the ping
command.

ticket 584

tests/test_ipalib/test_crud.py

@@ -74,12 +74,13 @@ class test_Create(CrudChecker):
         """
         api = self.get_api()
         assert list(api.Method.user_verb.options) == \
-            ['givenname', 'sn', 'initials', 'all', 'raw']
+            ['givenname', 'sn', 'initials', 'all', 'raw', 'version']
         for param in api.Method.user_verb.options():
-            assert param.required is True
+            if param.name != 'version':
+                assert param.required is True
         api = self.get_api(options=('extra?',))
         assert list(api.Method.user_verb.options) == \
-            ['givenname', 'sn', 'initials', 'extra', 'all', 'raw']
+            ['givenname', 'sn', 'initials', 'extra', 'all', 'raw', 'version']
         assert api.Method.user_verb.options.extra.required is False
 
 
@@ -104,7 +105,7 @@ class test_Update(CrudChecker):
         """
         api = self.get_api()
         assert list(api.Method.user_verb.options) == \
-            ['givenname', 'initials', 'uidnumber', 'all', 'raw']
+            ['givenname', 'initials', 'uidnumber', 'all', 'raw', 'version']
         for param in api.Method.user_verb.options():
             if param.name in ['all', 'raw']:
                 assert param.required is True
@@ -132,7 +133,7 @@ class test_Retrieve(CrudChecker):
         Test the `ipalib.crud.Retrieve.get_options` method.
         """
         api = self.get_api()
-        assert list(api.Method.user_verb.options) == ['all', 'raw']
+        assert list(api.Method.user_verb.options) == ['all', 'raw', 'version']
 
 
 class test_Delete(CrudChecker):
@@ -180,7 +181,7 @@ class test_Search(CrudChecker):
         """
         api = self.get_api()
         assert list(api.Method.user_verb.options) == \
-            ['givenname', 'sn', 'uid', 'initials', 'all', 'raw']
+            ['givenname', 'sn', 'uid', 'initials', 'all', 'raw', 'version']
         for param in api.Method.user_verb.options():
             if param.name in ['all', 'raw']:
                 assert param.required is True

tests/test_ipalib/test_frontend.py

@@ -29,6 +29,7 @@ from ipalib.base import NameSpace
 from ipalib import frontend, backend, plugable, errors, parameters, config
 from ipalib import output
 from ipalib.parameters import Str
+from ipapython.version import API_VERSION
 
 def test_RULE_FLAG():
     assert frontend.RULE_FLAG == 'validation_rule'
@@ -431,6 +432,7 @@ class test_Command(ClassChecker):
             option0=u'option0',
             option1=u'option1',
             another_option='some value',
+            version=API_VERSION,
         )
         sub.validate(**okay)
 
@@ -561,7 +563,7 @@ class test_Command(ClassChecker):
                 return ('forward', args, kw)
 
         args = ('Hello,', 'world,')
-        kw = dict(how_are='you', on_this='fine day?')
+        kw = dict(how_are='you', on_this='fine day?', version=API_VERSION)
 
         # Test in server context:
         (api, home) = create_test_api(in_server=True)
@@ -569,7 +571,9 @@ class test_Command(ClassChecker):
         o = my_cmd()
         o.set_api(api)
         assert o.run.im_func is self.cls.run.im_func
-        assert ('execute', args, kw) == o.run(*args, **kw)
+        out = o.run(*args, **kw)
+        del kw['version']
+        assert ('execute', args, kw) == out
 
         # Test in non-server context
         (api, home) = create_test_api(in_server=False)