We've released a generic netlink python library -- gnlpy

To: <lvs-devel@xxxxxxxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>, <netdev@xxxxxxxxxxxxxxx>
Subject: We've released a generic netlink python library -- gnlpy
Cc: <kernel-team@xxxxxx>
From: Alex Gartrell <agartrell@xxxxxx>
Date: Wed, 20 May 2015 14:10:19 -0700
Hey everyone,

tl;dr; pure python generic netlink library with simple clients for ipvs and taskstats here:

At Facebook we rely upon ipvs for most of our layer-4 load balancing needs. It's mostly worked pretty great for us. The standard way to interact with ipvs is ipvsadm, which will use netlink sockets to make rpc calls to the kernel (things like adding/remove services and real servers). Because we run many, many instances of ipvs, we ended up scripting this away with a separate program that shells out to ipvsadm.

The down side to this approach was that we had to format the arguments and parse the result of the tool, which was kind of a pain. Additionally, we'd sometimes get into a bad state where the exec would fail or the binary wouldn't be there and the whole thing would kind of break. To my knowledge this never caused any kind of large scale incident, but it was an annoying thing to deal with.

At some point, we made some changes to ipvs (heterogenous pools) and we were in the position of needing to roll a new ipvsadm binary to take advantage of the functionality. That was fundamentally unappealing to yours truly, so I hacked together gnlpy (Generic NetLink PYthon library) instead. It's been in production for several months.

At some point thereafter, someone on the lvs-devel list mentioned wanting to interact with ipvs through python and I made a vague assurance that we'd open source this thing. Well here we are.

If you take a look at the code, you'll quickly notice that we haven't gone through the trouble of implementing every RPC call for the families we support and we certainly haven't gone through the trouble of implementing every generic netlink family. We welcome your pull requests :)

Alex Gartrell <agartrell@xxxxxx>
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