Neutron OVS agent on Windows

https://blueprints.launchpad.net/neutron/+spec/hyper-v-ovs-agent

Thanks to the porting of Open vSwitch to Hyper-V is is now also possible to have the Neutron OVS L2 agent to work on both Linux and Windows. Most of the porting activity consists in replacing Linux specific dependencies with portable alternatives in the Neutron OVS agent, considering in particular that the agent primarily execs OVS CLI commands, and that OVS has an identical command line interface on both Linux and Windows.

Problem Description

Current implementation of OVS agent has a few GNU/Linux specific components:

  • The use of rootwrap. This is not necessary on Windows.
  • fcntl is used in agent.linux.utils which is imported by agent.linux.ovs_lib. It is also used by eventlet to set non blocking I/O. fcntl is not available on Windows, so any dependency on this will be replaced with Windows compatible alternatives.
  • ovsdb_monitor.SimpleInterfaceMonitor currently only works on GNU/Linux. The reason for this is that agent.linux.async_process.AsyncProcess() uses platform specific components like the kill command. A Windows alternative will be created to address this.

Proposed Change

Considering that OVS agent currently uses a series of exec calls to ovs-vsctl and ovs-ofctl ovs_lib and parts (if not all) of utils will be almost identical on both Linux and Windows. This implies that they will have to be moved from neutron.agent.linux to a common location, e.g.: neutron.agent.common. A base class will be created and platform specific differences will be abstracted (for example, the need for rootwrap).

Data Model Impact

None

REST API Impact

None.

Security Impact

None.

Notifications Impact

None.

Other End User Impact

None.

Performance Impact

None.

IPv6 Impact

None.

Other Deployer Impact

This change will require the user to install Open vSwitch on Hyper-V before deploying neutron ovs agent, and make the binaries available in the PATH.

Developer Impact

None.

Community Impact

None

Alternatives

The Neutron Hyper-V agent offers already support for the ML2 plugin, which in turn allows interoperability with othe mechanism drivers, inclusing Open vSwitch. The main limitation of this option is that since Hyper-V does not support VXLAN or GRE encapsulation natively, networking is limited to the VLAN and flat options.

Implementation

Assignee(s)

Primary assignee:
gabriel-samfira

Work Items

  • Move neutron.agent.linux.ovs_lib and parts of neutron.agent.linux.utils to neutron.agent.common
  • Create a base class for interactig with Open vSwitch, and abstract away the differences that are platform specific.
  • remove the need for roowrap. Only enable it on GNU/Linux
  • update/add unit tests accordingly

Dependencies

This change does not directly depend on any other blueprint. It is however related to:

Testing

This feature will be tested by the Hyper-V CI.

Tempest Tests

Current tempest tests are sufficient.

Functional Tests

Functional tests will be added as needed.

API Tests

None.

Documentation Impact

User Documentation

Documentation should reflect that OVS agent now works on Hyper-V as well.

Developer Documentation

None.