[Kea-users] DHCP redundancy [faked-from]

Tue Nov 28 05:17:32 UTC 2017

We manage configurations with a Salt state, and the application we
integrated with Kea that we built in-house generates the scope definitions
as YAML, so it's easy to push changes into the Salt state file.

It's not fully automated yet as the Kea version we're using doesn't support
a configuration syntax test option, but that's on our internal roadmap so
that a merge to the master branch will trigger a Jenkins job to incorporate
updates automatically, test, and deploy.

The benefit for us of using Salt is that scope changes go through code
review like everything else, so that lowers the risk of bad changes and
builds an audit trail if they get introduced.

cheers,
Klaus

On Mon, Nov 27, 2017 at 7:49 AM, Hugh Connolly <hconnolly at gcet.net> wrote:

> Check out Rudder
>
>
> If very happy with it.
>
> https://www.rudder-project.org/site/
> Rudder <https://www.rudder-project.org/site/>
> www.rudder-project.org
> Rudder is an easy to use, web-driven, role-based solution for IT
> Infrastructure Automation and Compliance.
>
> That or Chef, Puppet etc.
>
>
> Or just rsync and cron.
> ------------------------------
> *From:* Sutherland, Rob <Robert.B.Sutherland at windstream.com>
> *Sent:* Thursday, November 23, 2017 10:10:16 AM
> *To:* Hugh Connolly; Klaus Steden; SoupNazi izaNpuoS
> *Cc:* KEA-Users (kea-users at lists.isc.org)
> *Subject:* RE: [Kea-users] DHCP redundancy [faked-from]
>
>
> I’m using that setup as well: Pacemaker with a replicated postgres lease
> database. It works quite well. There’s only one missing piece: a way to
> keep the configuration in sync across nodes. In the database, perhaps?
> (aside: the configuration is quite fluid in our production environment,
> changing multiple times per day).
>
>
>
> *From:* Kea-users [mailto:kea-users-bounces at lists.isc.org] *On Behalf Of *Hugh
> Connolly
> *Sent:* Wednesday, November 22, 2017 8:34 AM
> *To:* Klaus Steden; SoupNazi izaNpuoS
> *Cc:* KEA-Users (kea-users at lists.isc.org)
> *Subject:* Re: [Kea-users] DHCP redundancy [faked-from]
>
>
>
> I'm working on something similar.
>
>
>
> It uses 2+ Kea instances with the postgresql lease db in Amazons RDS.
>
> To manage the VIP the cluster uses ocf_heartbeat_IPaddr2 (pacemaker)
>
>
>
> Works quite well thus far.
>
>
>
> What do you think?
>
>
>
> One improvement (beyond in-housing the Postgresql cluster) that comes to
> mind is better fencing in PCS to restart the service or shutdown the node
> if there is a problem. Something beyond just checking that the service is
> running, maybe checking the ports?
>
>
>
> Was fairly straight forward to setup
> ------------------------------
>
> *From:* Kea-users <kea-users-bounces at lists.isc.org> on behalf of Klaus
> Steden <klausfiend at gmail.com>
> *Sent:* Friday, November 17, 2017 4:14:00 PM
> *To:* SoupNazi izaNpuoS
> *Cc:* KEA-Users (kea-users at lists.isc.org)
> *Subject:* Re: [Kea-users] DHCP redundancy
>
>
>
>
>
> Our implementation uses a single database backend (which is itself HA, but
> the endpoint is a VIP, so it appears to be just a single host)  with a
> different server per environment running a Kea server. It seems they
> coexist quite happily as long as they're not trying to both handle the same
> row/table, which means each environment only uses a single IP helper.
>
>
>
> We use Monit on the servers themselves to keep the Kea daemon running,
> since as noted it doesn't retry when it encounters an error talking to the
> database; the whole system is generally fairly resilient, FWIW, even if
> it's less than industrial strength.
>
>
>
> cheers,
>
> Klaus
>
>
>
> On Fri, Nov 17, 2017 at 6:48 AM, SoupNazi izaNpuoS <soupnazi34 at gmail.com>
> wrote:
>
> Not at all.  It does split the pools, automatically.  You just need to
> make sure you don't use more than 90% of your addresses as it may have
> difficulty transferring IPs amongst the devices if you do (say if the
> secondary runs out, the primary may not be able to send IPs to it).
>
>
>
> On Fri, Nov 17, 2017 at 9:44 AM, John Ratliff <john at bluemarble.net> wrote:
>
> On 11/17/2017 9:37 AM, SoupNazi izaNpuoS wrote:
>
> Out of curiosity, was there a reason you didn't use the built in failover
> configuration in ISC DHCP?
>
>
> It's extremely confusing to me. Perhaps my understanding is flawed, but as
> I understand it, you need to split your pool and have one side responsible
> for their individual split. Our pools do not have enough spare IPs to allow
> that. It just never seemed work the effort.
>
> --John
>
>
> On Fri, Nov 17, 2017 at 9:25 AM, John Ratliff <john at bluemarble.net
> <mailto:john at bluemarble.net>> wrote:
>
>     I'm seeking best practice advice on how to setup DHCP server
>     redundancy with kea.
>
>     With ISC DHCP, I used VRRP with two servers and configured it to
>     send the dhcp-server-identifier option as the VRRP IP. Then I would
>     run a script that sync'd the lease database automatically via cron.
>
>     This process is messy and error prone, so I would like to use kea
>     instead.
>
>     The subnets I am allocating via DHCP is not the same subnet that the
>     server is in, so we use ip-helper statements to forward DHCP
>     requests to the server.
>
>     I have kea using mySQL as a lease backend. The mySQL server is not
>     on the same machine as kea.
>
>     My first thought was to use VRRP and supply the
>     dhcp-server-identifier option again. I ran into a problem though
>     that if kea started before VRRP, it wouldn't listen on the VRRP IP.
>     There is probably a solution to that, but I don't have one yet.
>
>     So then I changed the router configuration to use two ip-helper
>     statements, sending the request to both primary and secondary kea
>     servers; I also removed the dhcp-server-identifier option. This
>     seems to work.
>
>     Is this a reasonable setup for DHCP redundancy with kea? Is there a
>     better option I might want to consider? Are there any concerns I
>     should be aware of with both servers being active?
>
>     Thanks.
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