2015-05-20 21:12:24

by Alex Gartrell

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

Hey everyone,

tl;dr; pure python generic netlink library with simple clients for ipvs
and taskstats here: https://github.com/facebook/gnlpy

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 <[email protected]>


2015-05-20 23:33:14

by Cong Wang

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Subject: Re: We've released a generic netlink python library -- gnlpy

On Wed, May 20, 2015 at 2:10 PM, Alex Gartrell <[email protected]> wrote:
> Hey everyone,
>
> tl;dr; pure python generic netlink library with simple clients for ipvs and
> taskstats here: https://github.com/facebook/gnlpy

libnl should have python support for generic netlink too:

$ ls python/netlink/genl/
capi.i __init__.py Makefile Makefile.am Makefile.in

but I never use its python module so not sure if it works... ;)

2015-05-21 15:00:27

by Edward Cree

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Subject: Re: We've released a generic netlink python library -- gnlpy

On 21/05/15 00:33, Cong Wang wrote:
> On Wed, May 20, 2015 at 2:10 PM, Alex Gartrell <[email protected]> wrote:
>> Hey everyone,
>>
>> tl;dr; pure python generic netlink library with simple clients for ipvs and
>> taskstats here: https://github.com/facebook/gnlpy
> libnl should have python support for generic netlink too:
>
> $ ls python/netlink/genl/
> capi.i __init__.py Makefile Makefile.am Makefile.in
>
> but I never use its python module so not sure if it works... ;)
There is also pyroute2.netlink.generic
<https://pypi.python.org/pypi/pyroute2>
which does work but it's a bit clunky imho.