MidoNet is a system which implements an abstract, software-defined virtual network atop an existing IP fabric. That means that packets that enter a MidoNet deployment will then leave it at the location and with the alterations they would have had if they'd actually traversed the networking equipment defined in the deployment's virtual topology, or as close to it as we can manage.

A MidoNet deployment consists a few kinds of nodes, all connected in an IP network. Many nodes run Midolman, and are where traffic enters and leaves. Traffic is sent from its entry point (the ingress node) to its exit point (the egress node) via tunnels; see the tunnel management document. The network's virtual topology and associated information is stored in ZooKeeper, and per-connection state which is shared between nodes is stored in Cassandra -- all the Midolman nodes which compose a virtual network must have connectivity to the ZooKeeper and Cassandra clusters, as that's how they coordinate. The web-based REST API described here is provided by nodes running MidoNet's API service in a webserver. These API server nodes will read and modify the virtual topology configuration, so they need to have connectivity to the ZooKeeper cluster, but not necessarialy any other node types.

The MidoNet project is split into several submodules:

This contains the various pieces that compose the Midonet controller node brain. Controller nodes take care of orchestrating the configuration of all Midonet subcomponents, as well as coordinating with other external devices and systems, such as VTEP switches, the backend services holding our Network State DataBase (e.g: Zookeeper and Cassandra), etc.

This holds basic classes for parsing, building, and manipulating packets of various network protocol types.

Contains basic utilities used by the other modules, and is described here.

Contains the MidoNet edge controller code, as described here.

Contains the implementation of the MidoNet REST API.

Code for speaking the netlink protocol over a netlink socket, generally for communicating with the OS kernel.

Code for interacting (receiving notifications and sending commands) to the kernel's Open Datapath module.

Most dependencies are pulled in by the gradle build scripts, however there are some prerequisites:

• java 7 jdk
• protobufs compiler
• fpm (ruby gem) to build debian/rpm packages
• rpm

The brain directory contains an odl-ovsdb git submodule with code that must be compiled in order to generate dependencies needed in various midonet components. Before any build tasks, ensure that you have the right version of odl-ovsdb by executing:

~/midonet$ git submodule update --init --recursive

~/midonet$ ./gradlew

This will build all the modules while running all the tests from all the modules. To skip the tests, you can run the command:

~/midonet$ ./gradlew -x test

The build script provides targets to build debian and rpm packages. In all cases packages will be found in midolman/build/packages/ and midonet-api/build/packages.

Building debian packages:

~/midonet$ ./gradlew debian -x test

RPM packages targeted for RHEL 6.5:

~/midonet$ ./gradlew rpm -x test

RHEL 7 packages:

~/midonet$ ./gradlew rpm -x test -PrhelTarget=7

On ubuntu this requires the rpm tools which you can install with

# apt-get install rpm

~/midonet$ ./gradlew test