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Pallet crate for working with OpenVSwitch

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README.md

ovs-crate

A Pallet crate to work with OpenVSwitch (OVS).

OVS is a great piece of software and a natural fit for connection virtual machines together, and hence a good fit for use with pallet.

For the moment ovs-crate assumes OVS is always being set up on Ubuntu 12.X hosts. This restriction can loosened in the future if other people provide variations that works on other distributions and versions.

Getting started

For your lein2 project simply add the following dependency to your project.clj:

[boardintelligence/ovs-crate 0.1.0-SNAPSHOT]

Useage

The crate provides a server-spec ovs-crate.specs/ovs-server for which the :configure phase does the following:

  • Installs the required packages
  • Sets up any number of OVS bridges as specified by config in the lift :environment

NOTE: I have not found a way to make GRE+IPSec work after :configure without rebooting the server. Please do this either via the phase :reboot provided in the server spec, or manually. It is only needed the first time OVS is installed so I don't want to automatially do this. I'm guessing it has something to do with the OVS dkms kernel module but form the looks of it it's loaded before a reboot so it may be a matter of being loaded at the wrong time. If you know how to avoid this reboot - please let me know!

Apart from the :configure phase there is one more function (and phase) that can be used for administrating OVS. This is ovs-crate.api/recreate-all-gre-connections which is used to just perform the GRE connection setup (since this may need updating as more OVS bridges are added to the VLAN).

Details can be found below in their respective sections.

Configuration for the :configure phase of ovs-crate.specs/ovs-server

The :configure phase of the ovs-server spec assumes that the environment passed to pallet's lift operation looks like this:

{:host-config
 {"host.to.configure"
  {:ovs-info {:interfaces-file (utils/resource-path "etc-network-interfaces") ;; the /etc/network/intefaces file to use for host
              :bridges [{:name "private-br0" ;; the name of the OVS bridge
                         :host-interfaces-to-connect ["priv0"] ;; a vector of interfaces on the host to connect to bridge
                         :gre-connections [{:remote-ip "5.5.5.5"  ;; the remote ip of the remote bridge to connect
                                            :psk "the secret key" ;; the preshared key to use for connection
                                           }]
                         :act-as-forwarder {:from "priv0
                                            :via "eth0"
                                            :source "10.20.20.0/255.255.255.0"} ;; host is setup to act as NAT/forwarder from priv0 to eth0
                        }]}}}}

(utils/resource-path is a utility function provided by pallet to look for a specific relative path on the classpath)

We opt to let the user provide his own complete /etc/network/intefaces file (per host) to allow for the greatest flexibility. Note that both bridges and gre-connections are vectors allowing for several bridges and several gre-connections per bridge.

Connecing OVS bridges on different hosts into one big VLAN

The GRE connections specified are created during :configure, but if you then add more connections you may not want to run through the whole configure phase but instead just update the GRE connections. The phase named :recreate-all-gre-connections does just this and exists for the ovs-crate.specs/ovs-server server spec.

License

Copyright © 2013 Board Intelligence

Distributed under the MIT License, see http://boardintelligence.mit-license.org for details.

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