vault: cache the transport certificate on client

Cache the KRA transport certificate on disk (in ~/.cache/ipa) as well as
in memory.

https://fedorahosted.org/freeipa/ticket/6652

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

ipaclient/remote_plugins/__init__.py

@@ -12,6 +12,7 @@ import time
 from . import compat
 from . import schema
 from ipaclient.plugins.rpcclient import rpcclient
+from ipalib.constants import USER_CACHE_PATH
 from ipapython.dnsutil import DNSName
 from ipapython.ipa_log_manager import log_mgr
 
@@ -19,7 +20,7 @@ logger = log_mgr.get_logger(__name__)
 
 
 class ServerInfo(collections.MutableMapping):
-    _DIR = os.path.join(schema.USER_CACHE_PATH, 'ipa', 'servers')
+    _DIR = os.path.join(USER_CACHE_PATH, 'ipa', 'servers')
 
     def __init__(self, api):
         hostname = DNSName(api.env.server).ToASCII()

ipaclient/remote_plugins/schema.py

@@ -15,6 +15,7 @@ import six
 
 from ipaclient.frontend import ClientCommand, ClientMethod
 from ipalib import errors, parameters, plugable
+from ipalib.constants import USER_CACHE_PATH
 from ipalib.errors import SchemaUpToDate
 from ipalib.frontend import Object
 from ipalib.output import Output
@@ -29,17 +30,6 @@ FORMAT = '1'
 if six.PY3:
     unicode = str
 
-USER_CACHE_PATH = (
-    os.environ.get('XDG_CACHE_HOME') or
-    os.path.join(
-        os.environ.get(
-            'HOME',
-            os.path.expanduser('~')
-        ),
-        '.cache'
-    )
-)
-
 _TYPES = {
     'DN': DN,
     'DNSName': DNSName,