Add a templating mechanism in the flag parsing.

Add a state_path flag that will be used as the top-level dir for all other state (such as images, instances, buckets, networks, etc).
This way you only need to change one flag to put all your state in e.g. /var/lib/nova. This simplifies packaging quite a bit.

7 files changed, 37 insertions, 12 deletions

diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 890d79fba..50a9d316b 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -47,7 +47,7 @@ from nova.compute import power_state
 
 
 FLAGS = flags.FLAGS
-flags.DEFINE_string('instances_path', utils.abspath('../instances'),
+flags.DEFINE_string('instances_path', '$state_path/instances',
                     'where instances are stored on disk')
 flags.DEFINE_string('compute_driver', 'nova.virt.connection.get_connection',
                     'Driver to use for volume creation')
diff --git a/nova/compute/monitor.py b/nova/compute/monitor.py
index ce45b14f6..22653113a 100644
--- a/nova/compute/monitor.py
+++ b/nova/compute/monitor.py
@@ -46,7 +46,7 @@ flags.DEFINE_integer('monitoring_instances_delay', 5,
                      'Sleep time between updates')
 flags.DEFINE_integer('monitoring_instances_step', 300,
                      'Interval of RRD updates')
-flags.DEFINE_string('monitoring_rrd_path', '/var/nova/monitor/instances',
+flags.DEFINE_string('monitoring_rrd_path', '$state_path/monitor/instances',
                     'Location of RRD files')
 
 
diff --git a/nova/crypto.py b/nova/crypto.py
index d73559587..aacc50b17 100644
--- a/nova/crypto.py
+++ b/nova/crypto.py
@@ -40,9 +40,9 @@ from nova import flags
 
 FLAGS = flags.FLAGS
 flags.DEFINE_string('ca_file', 'cacert.pem', 'Filename of root CA')
-flags.DEFINE_string('keys_path', utils.abspath('../keys'),
+flags.DEFINE_string('keys_path', '$state_path/keys',
                     'Where we keep our keys')
-flags.DEFINE_string('ca_path', utils.abspath('../CA'),
+flags.DEFINE_string('ca_path', '$state_path/CA',
                     'Where we keep our root CA')
 flags.DEFINE_boolean('use_intermediate_ca', False,
                      'Should we use intermediate CAs for each project?')
diff --git a/nova/flags.py b/nova/flags.py
index f7ae26050..cb9fa105b 100644
--- a/nova/flags.py
+++ b/nova/flags.py
@@ -24,6 +24,7 @@ where they're used.
 import getopt
 import os
 import socket
+import string
 import sys
 
 import gflags
@@ -38,11 +39,12 @@ class FlagValues(gflags.FlagValues):
 
     """
 
-    def __init__(self):
+    def __init__(self, extra_context=None):
         gflags.FlagValues.__init__(self)
         self.__dict__['__dirty'] = []
         self.__dict__['__was_already_parsed'] = False
         self.__dict__['__stored_argv'] = []
+        self.__dict__['__extra_context'] = extra_context
 
     def __call__(self, argv):
         # We're doing some hacky stuff here so that we don't have to copy
@@ -112,7 +114,7 @@ class FlagValues(gflags.FlagValues):
     def ParseNewFlags(self):
         if '__stored_argv' not in self.__dict__:
             return
-        new_flags = FlagValues()
+        new_flags = FlagValues(self)
         for k in self.__dict__['__dirty']:
             new_flags[k] = gflags.FlagValues.__getitem__(self, k)
 
@@ -134,9 +136,29 @@ class FlagValues(gflags.FlagValues):
     def __getattr__(self, name):
         if self.IsDirty(name):
             self.ParseNewFlags()
-        return gflags.FlagValues.__getattr__(self, name)
+        val = gflags.FlagValues.__getattr__(self, name)
+        if type(val) is str:
+            tmpl = string.Template(val)
+            context = [self, self.__dict__['__extra_context']]
+            return tmpl.substitute(StrWrapper(context))
+        return val
 
 
+class StrWrapper(object):
+    """Wrapper around FlagValues objects
+
+    Wraps FlagValues objects for string.Template so that we're
+    sure to return strings."""
+    def __init__(self, context_objs):
+        self.context_objs = context_objs
+
+    def __getitem__(self, name):
+        for context in self.context_objs:
+            val = getattr(context, name, False)
+            if val:
+                return str(val)
+        raise KeyError(name)
+
 FLAGS = FlagValues()
 gflags.FLAGS = FLAGS
 gflags.DEFINE_flag(gflags.HelpFlag(), FLAGS)
@@ -222,8 +244,11 @@ DEFINE_string('vpn_key_suffix',
 
 DEFINE_integer('auth_token_ttl', 3600, 'Seconds for auth tokens to linger')
 
+DEFINE_string('state_path', os.path.join(os.path.dirname(__file__), '../'),
+              "Top-level directory for maintaining nova's state")
+
 DEFINE_string('sql_connection',
-              'sqlite:///%s/nova.sqlite' % os.path.abspath("./"),
+              'sqlite:///$state_path/nova.sqlite',
               'connection string for sql database')
 
 DEFINE_string('compute_manager', 'nova.compute.manager.ComputeManager',
diff --git a/nova/network/linux_net.py b/nova/network/linux_net.py
index 391abfb76..7b00e65d4 100644
--- a/nova/network/linux_net.py
+++ b/nova/network/linux_net.py
@@ -38,7 +38,7 @@ flags.DEFINE_string('dhcpbridge_flagfile',
                     '/etc/nova/nova-dhcpbridge.conf',
                     'location of flagfile for dhcpbridge')
 
-flags.DEFINE_string('networks_path', utils.abspath('../networks'),
+flags.DEFINE_string('networks_path', '$state_path/networks',
                     'Location to keep network config files')
 flags.DEFINE_string('public_interface', 'vlan1',
                     'Interface for public IP addresses')
diff --git a/nova/objectstore/bucket.py b/nova/objectstore/bucket.py
index 697982538..82767e52f 100644
--- a/nova/objectstore/bucket.py
+++ b/nova/objectstore/bucket.py
@@ -33,7 +33,7 @@ from nova.objectstore import stored
 
 
 FLAGS = flags.FLAGS
-flags.DEFINE_string('buckets_path', utils.abspath('../buckets'),
+flags.DEFINE_string('buckets_path', '$state_path/buckets',
                     'path to s3 buckets')
 
 
diff --git a/nova/objectstore/image.py b/nova/objectstore/image.py
index 4554444fa..7292dbab8 100644
--- a/nova/objectstore/image.py
+++ b/nova/objectstore/image.py
@@ -39,8 +39,8 @@ from nova.objectstore import bucket
 
 
 FLAGS = flags.FLAGS
-flags.DEFINE_string('images_path', utils.abspath('../images'),
-                        'path to decrypted images')
+flags.DEFINE_string('images_path', '$state_path/images',
+                    'path to decrypted images')
 
 
 class Image(object):