compat: Save server's API version in for pre-schema servers

When client comunicates with server that doesn't support 'schema'
command it needs to determine its api version to be able to use the
right compat code. Storing information about server version reduces the
need to call 'env' or 'ping' command only to first time the server is
contacted.

https://fedorahosted.org/freeipa/ticket/6069

Reviewed-By: Jan Cholasta <jcholast@redhat.com>

ipaclient/remote_plugins/__init__.py

@@ -2,23 +2,90 @@
 # Copyright (C) 2016  FreeIPA Contributors see COPYING for license
 #
 
+import collections
+import errno
+import json
+import os
+
 from . import compat
 from . import schema
 from ipaclient.plugins.rpcclient import rpcclient
+from ipaplatform.paths import paths
+from ipapython.dnsutil import DNSName
+from ipapython.ipa_log_manager import log_mgr
+
+logger = log_mgr.get_logger(__name__)
+
+
+class ServerInfo(collections.MutableMapping):
+    _DIR = os.path.join(paths.USER_CACHE_PATH, 'ipa', 'servers')
+
+    def __init__(self, api):
+        hostname = DNSName(api.env.server).ToASCII()
+        self._path = os.path.join(self._DIR, hostname)
+        self._dict = {}
+        self._dirty = False
+
+        self._read()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_exc_info):
+        if self._dirty:
+            self._write()
+
+    def _read(self):
+        try:
+            with open(self._path, 'r') as sc:
+                self._dict = json.load(sc)
+        except EnvironmentError as e:
+            if e.errno != errno.ENOENT:
+                logger.warning('Failed to read server info: {}'.format(e))
+
+    def _write(self):
+        try:
+            try:
+                os.makedirs(self._DIR)
+            except EnvironmentError as e:
+                if e.errno != errno.EEXIST:
+                    raise
+            with open(self._path, 'w') as sc:
+                json.dump(self._dict, sc)
+        except EnvironmentError as e:
+            logger.warning('Failed to write server info: {}'.format(e))
+
+    def __getitem__(self, key):
+        return self._dict[key]
+
+    def __setitem__(self, key, value):
+        self._dirty = key not in self._dict or self._dict[key] != value
+        self._dict[key] = value
+
+    def __delitem__(self, key):
+        del self._dict[key]
+        self._dirty = True
+
+    def __iter__(self):
+        return iter(self._dict)
+
+    def __len__(self):
+        return len(self._dict)
 
 
 def get_package(api):
     if api.env.in_tree:
         from ipaserver import plugins
     else:
-        client = rpcclient(api)
+        with ServerInfo(api) as server_info:
-        client.finalize()
+            client = rpcclient(api)
-        try:
+            client.finalize()
-            plugins = schema.get_package(api, client)
+            try:
-        except schema.NotAvailable:
+                plugins = schema.get_package(api, server_info, client)
-            plugins = compat.get_package(api, client)
+            except schema.NotAvailable:
-        finally:
+                plugins = compat.get_package(api, server_info, client)
-            if client.isconnected():
+            finally:
-                client.disconnect()
+                if client.isconnected():
+                    client.disconnect()
 
     return plugins

ipaclient/remote_plugins/compat.py

@@ -31,23 +31,26 @@ class CompatObject(Object):
     pass
 
 
-def get_package(api, client):
+def get_package(api, server_info, client):
-    if not client.isconnected():
-        client.connect(verbose=False)
-
-    env = client.forward(u'env', u'api_version', version=u'2.0')
     try:
-        server_version = env['result']['api_version']
+        server_version = server_info['version']
     except KeyError:
-        ping = client.forward(u'ping', version=u'2.0')
+        if not client.isconnected():
+            client.connect(verbose=False)
+        env = client.forward(u'env', u'api_version', version=u'2.0')
         try:
-            match = re.search(u'API version (2\.[0-9]+)', ping['summary'])
+            server_version = env['result']['api_version']
         except KeyError:
-            match = None
+            ping = client.forward(u'ping', u'api_version', version=u'2.0')
-        if match is not None:
+            try:
-            server_version = match.group(1)
+                match = re.search(u'API version (2\.[0-9]+)', ping['summary'])
-        else:
+            except KeyError:
-            server_version = u'2.0'
+                match = None
+            if match is not None:
+                server_version = match.group(1)
+            else:
+                server_version = u'2.0'
+        server_info['version'] = server_version
     server_version = LooseVersion(server_version)
 
     package_names = {}

ipaclient/remote_plugins/schema.py

@@ -19,6 +19,7 @@ from ipalib import errors, parameters, plugable
 from ipalib.frontend import Object
 from ipalib.output import Output
 from ipalib.parameters import DefaultFrom, Flag, Password, Str
+from ipaplatform.paths import paths
 from ipapython.dn import DN
 from ipapython.dnsutil import DNSName
 from ipapython.ipa_log_manager import log_mgr
@@ -55,17 +56,6 @@ _PARAMS = {
     'str': parameters.Str,
 }
 
-USER_CACHE_PATH = (
-    os.environ.get('XDG_CACHE_HOME') or
-    os.path.join(
-        os.environ.get(
-            'HOME',
-            os.path.expanduser('~')
-        ),
-        '.cache'
-    )
-)
-
 logger = log_mgr.get_logger(__name__)
 
 
@@ -359,62 +349,6 @@ class NotAvailable(Exception):
     pass
 
 
-class ServerInfo(collections.MutableMapping):
-    _DIR = os.path.join(USER_CACHE_PATH, 'ipa', 'servers')
-
-    def __init__(self, api):
-        hostname = DNSName(api.env.server).ToASCII()
-        self._path = os.path.join(self._DIR, hostname)
-        self._dict = {}
-        self._dirty = False
-
-        self._read()
-
-    def __enter__(self):
-        return self
-
-    def __exit__(self, *_exc_info):
-        if self._dirty:
-            self._write()
-
-    def _read(self):
-        try:
-            with open(self._path, 'r') as sc:
-                self._dict = json.load(sc)
-        except EnvironmentError as e:
-            if e.errno != errno.ENOENT:
-                logger.warning('Failed to read server info: {}'.format(e))
-
-    def _write(self):
-        try:
-            try:
-                os.makedirs(self._DIR)
-            except EnvironmentError as e:
-                if e.errno != errno.EEXIST:
-                    raise
-            with open(self._path, 'w') as sc:
-                json.dump(self._dict, sc)
-        except EnvironmentError as e:
-            logger.warning('Failed to write server info: {}'.format(e))
-
-    def __getitem__(self, key):
-        return self._dict[key]
-
-    def __setitem__(self, key, value):
-        self._dirty = key not in self._dict or self._dict[key] != value
-        self._dict[key] = value
-
-    def __delitem__(self, key):
-        del self._dict[key]
-        self._dirty = True
-
-    def __iter__(self):
-        return iter(self._dict)
-
-    def __len__(self):
-        return len(self._dict)
-
-
 class Schema(object):
     """
     Store and provide schema for commands and topics
@@ -436,7 +370,7 @@ class Schema(object):
 
     """
     namespaces = {'classes', 'commands', 'topics'}
-    _DIR = os.path.join(USER_CACHE_PATH, 'ipa', 'schema')
+    _DIR = os.path.join(paths.USER_CACHE_PATH, 'ipa', 'schema')
 
     def __init__(self, api, server_info, client):
         self._dict = {}
@@ -618,13 +552,12 @@ class Schema(object):
                     self._dict[ns][member].update(self._help[ns][member])
 
 
-def get_package(api, client):
+def get_package(api, server_info, client):
     try:
         schema = api._schema
     except AttributeError:
-        with ServerInfo(api.env.hostname) as server_info:
+        schema = Schema(api, server_info, client)
-            schema = Schema(api, server_info, client)
+        object.__setattr__(api, '_schema', schema)
-            object.__setattr__(api, '_schema', schema)
 
     fingerprint = str(schema['fingerprint'])
     package_name = '{}${}'.format(__name__, fingerprint)

ipaplatform/base/paths.py

@@ -21,6 +21,8 @@
 This base platform module exports default filesystem paths.
 '''
 
+import os
+
 
 class BasePathNamespace(object):
     BASH = "/bin/bash"
@@ -353,4 +355,17 @@ class BasePathNamespace(object):
     IPA_CUSTODIA_AUDIT_LOG = '/var/log/ipa-custodia.audit.log'
     IPA_GETKEYTAB = '/usr/sbin/ipa-getkeytab'
 
+    @property
+    def USER_CACHE_PATH(self):
+        return (
+            os.environ.get('XDG_CACHE_HOME') or
+            os.path.join(
+                os.environ.get(
+                    'HOME',
+                    os.path.expanduser('~')
+                ),
+                '.cache'
+            )
+        )
+
 path_namespace = BasePathNamespace