Make VM and wfagent names appear as node names in the Capnet Protocol.

This was tonight's adventure.  Holy cow.  I feel like I need to go take
a shower.  Apparently, despite the fact that Neutron and Nova have
coexisted for many years, Nova VMs have a hostname that doesn't resolve
to anything, and that Neutron knows nothing about.  This causes all
kinds of local hangups (i.e., sudo, ssh UseDNS), but ok, whatever.
Neutron has its own "DNS" names for the VMs; Nova has its own.  They
don't share info.

For us, it matters because we want the tenants to be able to create VMs
and wfagents with meaningful names, and have those names returned to the
Capnet Protocol as the node names.

Well, Neutron and Nova do not share this information.  The real way to
solve this is to ask Nova for the VM name from the Capnet Neutron agent,
when said agent sees a port binding update.  But we want to process
those pretty fast, and calling out to Keystone/Nova for a lookup on the
hot path is quite undesirable.  So instead, since we already have a
Capnet-specific binding update call that pushes local OVS dpid and
ofportno from the local node to the controller (which distributes it to
whichever Capnet agents are writing metadata files), if we can "find" a
nova VM name locally, we add that to the binding, and then the Neutron
server adds the name to the ports table in the DB.  Currently, we find
this by whacking through the libvirt.xml until we find an instance who
owns the device_name we are sending the binding update for.

It seems that the Neutron people have already staged in db schema
changes to support their pending new DNS feature.  This is coming, but
it's not here yet.  So we can use the new table field, but the
Neutron-Nova DNS thing doesn't exist in Liberty.  Eventually, Nova will
tell Neutron the name of the port and other DNS information.

networking_capnet/db/capnet_db.py

@@ -220,6 +220,18 @@ class CapnetDBMixin(agents_db.AgentDbMixin):
         port_id = binding['port_id']
         session = context.session
         
+        # yank out 'name' and 'dns_name' and put into port
+        name = None
+        dns_name = None
+        if 'name' in binding:
+            name = binding['name']
+            del binding['name']
+            pass
+        if 'dns_name' in binding:
+            name = binding['dns_name']
+            del binding['dns_name']
+            pass
+        
         with session.begin(subtransactions=True):
             query = session.query(CapnetPortBinding).filter(
                 CapnetPortBinding.port_id==port_id)
@@ -254,6 +266,17 @@ class CapnetDBMixin(agents_db.AgentDbMixin):
         
         cpb = query.first()
         foo = cpb.wfagent
+            
+        with session.begin(subtransactions=True):
+            if not cpb.port is None and (name or dns_name):
+                if name:
+                    cpb.port.name = name
+                if dns_name:
+                    cpb.port.dns_name = dns_name
+                
+                cpb = session.merge(cpb)
+                pass
+            pass
         
         self.__db_capnet_port_binding_notify(context,dict(cpb))
         pass

networking_capnet/plugins/ml2/drivers/capnet/capnet_neutron_agent.py

@@ -397,6 +397,7 @@ class CapnetControllerMetadataManager(object):
         """
         LOG.debug("creating metadata dict from binding %s" % (str(binding),))
         
+        wfagent_name = None
         if 'role' in binding:
             role = binding['role']
         elif 'wfagent' in binding and not binding['wfagent'] is None:
@@ -406,6 +407,9 @@ class CapnetControllerMetadataManager(object):
                 # For now, wfagents aren't special; just nodes
                 role = 'node'
                 pass
+            if 'name' in binding['wfagent']:
+                wfagent_name = binding['wfagent']['name']
+                pass
         else:
             role = 'node'
             pass
@@ -456,11 +460,16 @@ class CapnetControllerMetadataManager(object):
             domain_id = "%s-%s" % (network_id,subnet_id)
             owner_id = tenant_id
             
+            name = None
+            if 'name' in binding['port'] and binding['port']['name']:
+                name = binding['port']['name']
+            elif 'dns_name' in binding['port'] and binding['port']['dns_name']:
+                dns_name = binding['port']['dns_name']
+                pass
             mac = binding['port']['mac_address']
             port_id = binding['port_id']
             ipaddr = binding['ipallocation']['ip_address']
-            # XXX: get from nova???
-            nodename = ipaddr or port_id
+            nodename = name or wfagent_name or ipaddr or port_id
             # XXX: we currently don't get a mask!
             mask = '24'
             line = "node %s %s %s %s %s %s %s %s %s" \
@@ -1124,6 +1133,8 @@ class CapnetWorkflowAgentManager(object):
         port = self._setup_wfagent_port(context,wfagent)
         interface_name = self.ensure_running(wfagent,port)
         
+        self.agents[wfagent.id] = wfagent
+        
         return interface_name
 
     def delete(self,context,wfagent):
@@ -1155,6 +1166,21 @@ class CapnetWorkflowAgentManager(object):
             pass
         
         pass
+    
+    def get_wfagent_name_by_port_id(self,port_id):
+        wfagent = None
+        for wfagent in self.agents:
+            if wfagent.port_id == port_id:
+                break
+            else:
+                wfagent = None
+                pass
+            pass
+        if not wfagent is None and 'name' in wfagent:
+            return wfagent.name
+            pass
+        
+        return None
 
     def _bind(self,context,wfagent):
         """
@@ -1949,6 +1975,52 @@ class CapnetNeutronAgent(service.Service):
             resync_b = self.treat_devices_removed(device_info['removed'])
         # If one of the above operations fails => resync with plugin
         return (resync_a | resync_b)
+    
+    def __find_vm_name(self,device_name):
+        """
+        This is a nasty, nasty hack to find a VM name for a nova VM, and
+        pass it to Neutron.  We scrape it out of whichever libvirt
+        config file contains the device name!  Oh, I feel dirty.  But
+        it's Neutron's fault for not actually having a valid DNS story
+        that corresponds to Nova's VM name.  Whoever thought that might
+        be something anyone would ever want...
+        """
+        NOVADIR = '/var/lib/nova/instances'
+        try:
+            dirs = os.listdir(NOVADIR)
+            for dir in dirs:
+                lvcf = '%s/%s/libvirt.xml' % (NOVADIR,dir)
+                if os.path.exists(lvcf):
+                    LOG.debug("considering instance %s" % (dir,))
+                    f = file(lvcf)
+                    found_dname = False
+                    found_vname = False
+                    vname = None
+                    for line in f:
+                        LOG.debug("line = %s" % (line,))
+                        if 'target dev' in line and device_name in line:
+                            found_dname = True
+                        if '<nova:name>' in line and '</nova:name>' in line:
+                            found_vname = True
+                            vname = line.replace(' ','')
+                            vname = vname.replace('<nova:name>','')
+                            vname = vname.replace('</nova:name>','')
+                            vname = vname.rstrip('\n')
+                            pass
+                        if found_dname and found_vname:
+                            break
+                        pass
+                    f.close()
+                    if found_dname and found_vname:
+                        # Found it!
+                        return vname
+                    pass
+                pass
+        except:
+            import traceback
+            traceback.print_exc()
+            pass
+        return None
 
     def treat_devices_added_updated(self, devices):
         try:
@@ -1998,6 +2070,13 @@ class CapnetNeutronAgent(service.Service):
                     cn_binding['ofport'] = port.ofport
                     cn_binding['device_name'] = port.port_name
                     cn_binding['host'] = cfg.CONF.host
+                    
+                    # XXX: if Nova VM, figure out the name -- ugh.
+                    if device_details['device_owner'] == 'compute:nova':
+                        vm_name = self.__find_vm_name(port.port_name)
+                        if vm_name:
+                            cn_binding['dns_name'] = vm_name
+                        pass
         
                     LOG.debug("sending binding update: %s" % (str(cn_binding),))