Make nova-dhcpbridge use CONFIG_FILE over FLAGFILE

nova-dhcpbridge's FLAGFILE environment variable is one of the few
remaining references we have to "flags".

Switching to use a new environment variable is easy, but we need
to take care that when you upgrade the code the compute and network
services might not be restarted immediately.

If this happens, the services may launch a new dnsmasq (so rootwrap
needs to continue to support FLAGFILE) or an existing dnsmasq might run
the lease script (so the script needs to support FLAGFILE).

Change-Id: Ieb55daa2507abb8327c7f5a2ef2f682740f31a5d

bin/nova-dhcpbridge

@@ -95,8 +95,11 @@ def init_leases(network_id):
 
 def main():
     """Parse environment and arguments and call the approproate action."""
-    argv = config.parse_args(sys.argv,
-                             default_config_files=[os.environ['FLAGFILE']])
+    try:
+        config_file = os.environ['CONFIG_FILE']
+    except KeyError:
+        config_file = os.environ['FLAGFILE']
+    argv = config.parse_args(sys.argv, default_config_files=[config_file])
     logging.setup("nova")
 
     if int(os.environ.get('TESTING', '0')):

etc/nova/rootwrap.d/compute.filters

@@ -148,6 +148,7 @@ kill_radvd: KillFilter, root, /usr/sbin/radvd
 
 # nova/network/linux_net.py: dnsmasq call
 dnsmasq: DnsmasqFilter, /usr/sbin/dnsmasq, root
+dnsmasq_deprecated: DeprecatedDnsmasqFilter, /usr/sbin/dnsmasq, root
 
 # nova/network/linux_net.py: 'radvd', '-C', '%s' % _ra_file(dev, 'conf'..
 radvd: CommandFilter, /usr/sbin/radvd, root

etc/nova/rootwrap.d/network.filters

@@ -63,6 +63,7 @@ kill_radvd: KillFilter, root, /usr/sbin/radvd
 
 # nova/network/linux_net.py: dnsmasq call
 dnsmasq: DnsmasqFilter, /usr/sbin/dnsmasq, root
+dnsmasq_deprecated: DeprecatedDnsmasqFilter, /usr/sbin/dnsmasq, root
 
 # nova/network/linux_net.py: 'radvd', '-C', '%s' % _ra_file(dev, 'conf'..
 radvd: CommandFilter, /usr/sbin/radvd, root

nova/network/linux_net.py

@@ -840,7 +840,7 @@ def restart_dhcp(context, dev, network_ref):
             LOG.debug(_('Pid %d is stale, relaunching dnsmasq'), pid)
 
     cmd = ['env',
-           'FLAGFILE=%s' % CONF.dhcpbridge_flagfile,
+           'CONFIG_FILE=%s' % CONF.dhcpbridge_flagfile,
            'NETWORK_ID=%s' % str(network_ref['id']),
            'dnsmasq',
            '--strict-order',

nova/rootwrap/filters.py

@@ -72,9 +72,11 @@ class RegExpFilter(CommandFilter):
 class DnsmasqFilter(CommandFilter):
     """Specific filter for the dnsmasq call (which includes env)"""
 
+    CONFIG_FILE_ARG = 'CONFIG_FILE'
+
     def match(self, userargs):
         if (userargs[0] == 'env' and
-            userargs[1].startswith('FLAGFILE=') and
+            userargs[1].startswith(self.CONFIG_FILE_ARG) and
             userargs[2].startswith('NETWORK_ID=') and
             userargs[3] == 'dnsmasq'):
             return True
@@ -86,11 +88,16 @@ class DnsmasqFilter(CommandFilter):
 
     def get_environment(self, userargs):
         env = os.environ.copy()
-        env['FLAGFILE'] = userargs[1].split('=')[-1]
+        env[self.CONFIG_FILE_ARG] = userargs[1].split('=')[-1]
         env['NETWORK_ID'] = userargs[2].split('=')[-1]
         return env
 
 
+class DeprecatedDnsmasqFilter(DnsmasqFilter):
+    """Variant of dnsmasq filter to support old-style FLAGFILE"""
+    CONFIG_FILE_ARG = 'FLAGFILE'
+
+
 class KillFilter(CommandFilter):
     """Specific filter for the kill calls.
        1st argument is the user to run /bin/kill under

nova/tests/test_nova_rootwrap.py

@@ -54,15 +54,22 @@ class RootwrapTestCase(test.TestCase):
         filtermatch = wrapper.match_filter(self.filters, invalid)
         self.assertTrue(filtermatch is None)
 
-    def test_DnsmasqFilter(self):
-        usercmd = ['env', 'FLAGFILE=A', 'NETWORK_ID=foobar', 'dnsmasq', 'foo']
-        f = filters.DnsmasqFilter("/usr/bin/dnsmasq", "root")
+    def _test_DnsmasqFilter(self, filter_class, config_file_arg):
+        usercmd = ['env', config_file_arg + '=A', 'NETWORK_ID=foobar',
+                   'dnsmasq', 'foo']
+        f = filter_class("/usr/bin/dnsmasq", "root")
         self.assertTrue(f.match(usercmd))
         self.assertEqual(f.get_command(usercmd), ['/usr/bin/dnsmasq', 'foo'])
         env = f.get_environment(usercmd)
-        self.assertEqual(env.get('FLAGFILE'), 'A')
+        self.assertEqual(env.get(config_file_arg), 'A')
         self.assertEqual(env.get('NETWORK_ID'), 'foobar')
 
+    def test_DnsmasqFilter(self):
+        self._test_DnsmasqFilter(filters.DnsmasqFilter, 'CONFIG_FILE')
+
+    def test_DeprecatedDnsmasqFilter(self):
+        self._test_DnsmasqFilter(filters.DeprecatedDnsmasqFilter, 'FLAGFILE')
+
     def test_KillFilter(self):
         if not os.path.exists("/proc/%d" % os.getpid()):
             self.skipTest("Test requires /proc filesystem (procfs)")