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Posted to dev@mesos.apache.org by Zhitao Li <zh...@gmail.com> on 2016/05/25 22:50:56 UTC
Round robin DNS zookeeper record
Hi,
Can someone confirm whether the zookeeper library Mesos is using well
supports round robin DNS?
For example, if I have a round robin DNS entry `zookeeper-mesos-dc` which
resolves to five A records, would the --zk flag value `
zk://zookeeper-mesos-dc:2181/mesos` work on master, agents and any
framework using libmesos driver?
Also:
1. What happens if one of the A records changes in the DNS record? Do I
need to restart related Mesos processes?
2. What happens if one of the A records is not responsive (e.g. underlying
zookeeper server is dead)? Is the zookeeper library capable to avoid
the bad server?
Some pointer for me to find out the answer individually is also greatly
appreciated.
Thanks!
--
Cheers,
Zhitao Li
Re: Round robin DNS zookeeper record
Posted by Zhitao Li <zh...@gmail.com>.
Hi Joseph,
Thanks for the pointers! From the response it seems like our intended usage
should be fine, but I'll confirm separately if we decide to use that
pattern.
Thanks again.
On Wed, May 25, 2016 at 4:52 PM, Joseph Wu <jo...@mesosphere.io> wrote:
> Mesos passes the list inside between "zk://" and the first "/" directly
> into Zookeeper's C bindings.
> I'm not familiar enough with the Zookeeper API to say for certain, but it
> looks like this *does* support your round-robin scheme.
> You can double check here:
>
> https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L620-L650
> <
> https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L777
> >
>
> As for your other questions:
>
> 1) When the ZK connection is lost, Mesos will re-resolve the address as of
> MESOS-4546 (https://issues.apache.org/jira/browse/MESOS-4546).
>
> 2) Looks like ZK rotates between servers. When one server returns an
> error, it tries the next one, in a circle.
> Increment code:
>
> https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L1248
> Connection code:
>
> https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L1578-L1580
>
> On Wed, May 25, 2016 at 3:50 PM, Zhitao Li <zh...@gmail.com> wrote:
>
> > Hi,
> >
> > Can someone confirm whether the zookeeper library Mesos is using well
> > supports round robin DNS?
> >
> > For example, if I have a round robin DNS entry `zookeeper-mesos-dc`
> which
> > resolves to five A records, would the --zk flag value `
> > zk://zookeeper-mesos-dc:2181/mesos` work on master, agents and any
> > framework using libmesos driver?
> >
> > Also:
> > 1. What happens if one of the A records changes in the DNS record? Do I
> > need to restart related Mesos processes?
> > 2. What happens if one of the A records is not responsive (e.g.
> underlying
> > zookeeper server is dead)? Is the zookeeper library capable to avoid
> > the bad server?
> >
> > Some pointer for me to find out the answer individually is also greatly
> > appreciated.
> >
> > Thanks!
> >
> >
> > --
> > Cheers,
> >
> > Zhitao Li
> >
>
--
Cheers,
Zhitao Li
Re: Round robin DNS zookeeper record
Posted by Joseph Wu <jo...@mesosphere.io>.
Mesos passes the list inside between "zk://" and the first "/" directly
into Zookeeper's C bindings.
I'm not familiar enough with the Zookeeper API to say for certain, but it
looks like this *does* support your round-robin scheme.
You can double check here:
https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L620-L650
<https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L777>
As for your other questions:
1) When the ZK connection is lost, Mesos will re-resolve the address as of
MESOS-4546 (https://issues.apache.org/jira/browse/MESOS-4546).
2) Looks like ZK rotates between servers. When one server returns an
error, it tries the next one, in a circle.
Increment code:
https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L1248
Connection code:
https://github.com/apache/zookeeper/blob/release-3.4.8/src/c/src/zookeeper.c#L1578-L1580
On Wed, May 25, 2016 at 3:50 PM, Zhitao Li <zh...@gmail.com> wrote:
> Hi,
>
> Can someone confirm whether the zookeeper library Mesos is using well
> supports round robin DNS?
>
> For example, if I have a round robin DNS entry `zookeeper-mesos-dc` which
> resolves to five A records, would the --zk flag value `
> zk://zookeeper-mesos-dc:2181/mesos` work on master, agents and any
> framework using libmesos driver?
>
> Also:
> 1. What happens if one of the A records changes in the DNS record? Do I
> need to restart related Mesos processes?
> 2. What happens if one of the A records is not responsive (e.g. underlying
> zookeeper server is dead)? Is the zookeeper library capable to avoid
> the bad server?
>
> Some pointer for me to find out the answer individually is also greatly
> appreciated.
>
> Thanks!
>
>
> --
> Cheers,
>
> Zhitao Li
>