Guided Tour: The Neutron Security Group API

https://wiki.openstack.org/wiki/Neutron/SecurityGroups

API Extension

The API extension is the ‘front’ end portion of the code, which handles defining a REST-ful API, which is used by projects.

Database API

The Security Group API extension adds a number of methods to the database layer of Neutron

Agent RPC

This portion of the code handles processing requests from projects, after they have been stored in the database. It involves messaging all the L2 agents running on the compute nodes, and modifying the IPTables rules on each hypervisor.

• Plugin RPC classes
  • SecurityGroupServerRpcMixin - defines the RPC API that the plugin uses to communicate with the agents running on the compute nodes
  • SecurityGroupServerRpcMixin - Defines the API methods used to fetch data from the database, in order to return responses to agents via the RPC API
• Agent RPC classes
  • The SecurityGroupServerRpcApi defines the API methods that can be called by agents, back to the plugin that runs on the Neutron controller
  • The SecurityGroupAgentRpcCallbackMixin defines methods that a plugin uses to call back to an agent after performing an action called by an agent.

IPTables Driver

• prepare_port_filter takes a port argument, which is a dictionary object that contains information about the port - including the security_group_rules
• prepare_port_filter appends the port to an internal dictionary, filtered_ports which is used to track the internal state.
• Each security group has a chain in Iptables.
• The IptablesFirewallDriver has a method to convert security group rules into iptables statements.