Difference between revisions of "TricircleHowToReadCode"

Revision as of 01:52, 20 February 2017

(Work in progress)Learn the source code of Tricircle step by step

Experience the multi-region Tricircle networking first

Follow the installation guide: https://github.com/openstack/tricircle/blob/master/doc/source/multi-pod-installation-devstack.rst

Learn the source code will be used in the "How to play":

Step 1 ~ Step 4: no code of Tricircle will be involved

Step 5: Create pod instances

• The restful API request will be routed to V1Controller from RootController for the version is 'v1.0':

 tricircle/tricircle/api/controllers/root.py
 ...
 class RootController(object):
      ...
     @expose()
     def _lookup(self, version, *remainder):
         if version == 'v1.0':
             return V1Controller(), remainder

• In V1Controller, because the request is to create pod, so the request will be forwarded to the post function in PodsController. Post function will create the pod and az mapping record in pod table:

 tricircle/tricircle/api/controllers/pod.py
 ...
 class PodsController(rest.RestController):
   ...
   @expose(generic=True, template='json')
   def post(self, **kw):
       context = t_context.extract_context_from_environ()
       ...
       new_pod = core.create_resource(
                   context, models.Pod,
                   {'pod_id': _uuid,
                    'region_name': region_name,
                    'pod_az_name': pod_az_name,
                    'dc_name': dc_name,
                    'az_name': az_name})

Step 6: Create network/subnet in central Neutron server

The central_plugin.py will be called because the core plugin of central Neutron is configured like this:

   core_plugin = tricircle.network.central_plugin.TricirclePlugin

• The request is handled by create_network when net1 is to be created:

 tricircle/tricircle/network/central_plugin.py
 ...
 class TricirclePlugin(db_base_plugin_v2.NeutronDbPluginV2,
                     security_groups.TricircleSecurityGroupMixin,
                     external_net_db.External_net_db_mixin,
                     portbindings_db.PortBindingMixin,
                     extradhcpopt_db.ExtraDhcpOptMixin,
                     l3_db.L3_NAT_dbonly_mixin,
                     l3_attrs_db.ExtraAttributesMixin):
  ...
  def create_network(self, context, network):
       net_data = network[attributes.NETWORK]
       ...

• The request is handled by create_subnet when 10.0.1.0/24 subnet is created in net1:

 tricircle/tricircle/network/central_plugin.py
 ...
 class TricirclePlugin(db_base_plugin_v2.NeutronDbPluginV2,
                     security_groups.TricircleSecurityGroupMixin,
                     external_net_db.External_net_db_mixin,
                     portbindings_db.PortBindingMixin,
                     extradhcpopt_db.ExtraDhcpOptMixin,
                     l3_db.L3_NAT_dbonly_mixin,
                     l3_attrs_db.ExtraAttributesMixin):
 ...
 def create_subnet(self, context, subnet):
       subnet_data = subnet['subnet']
       ...