Service Discovery with Mesos-DNS

#1

Post by presspot » Wed, Jan 21, 2015, 3:11 PM UTC

Service Discovery with Mesos-DNS
mesosphere.com

Re: Service Discovery with Mesos-DNS

#2

Post by m_eiman » Wed, Jan 21, 2015, 3:50 PM UTC

Doesn't this sound a lot like DNS-SD over mDNS?

Re: Service Discovery with Mesos-DNS

#3

Post by preillyme » Wed, Jan 21, 2015, 3:51 PM UTC

Awesome, Mesos-DNS is simple and stateless. Unlike Consul and SkyDNS, it does not require consensus mechanisms, persistent storage, or a replicated log. This is possible because Mesos-DNS does not implement heartbeats, health monitoring, or lifetime management for applications. This functionality is already available by the Mesos master, slaves, and frameworks.

Re: Service Discovery with Mesos-DNS

#4

Post by vertex-four » Wed, Jan 21, 2015, 4:28 PM UTC

m_eiman wrote: post #2

Doesn't this sound a lot like DNS-SD over mDNS?

I think it's centralised, so you don't need to either have all your machines on one subnet or configure your routers (if you can) to forward DNS-SD packets between all your subnets, probably creating a small broadcast storm at scale.

Re: Service Discovery with Mesos-DNS

#5

Post by presspot » Wed, Jan 21, 2015, 4:41 PM UTC

Here is the Github repo https://github.com/mesosphere/mesos-dns

Re: Service Discovery with Mesos-DNS

#6

Post by vidarh » Wed, Jan 21, 2015, 4:58 PM UTC

preillyme wrote: post #3

Awesome, Mesos-DNS is simple and stateless. Unlike Consul and SkyDNS, it does not require consensus mechanisms, persistent storage, or a replicated log. This is possible because Mesos-DNS does not implement heartbeats, health monitoring, or lifetime management for applications. This functionality is already available by the Mesos master, slaves, and frameworks.

The same is the case for SkyDNS2. It runs just fine against our Etcd backends.

In both cases the combination (SkyDNS + Etcd or Consul) looks far less complicated than Mesos, so I don't really see what you think you gain. If you already have other reasons to want to run Mesos, sure.

Re: Service Discovery with Mesos-DNS

#7

Post by tknaup » Wed, Jan 21, 2015, 5:08 PM UTC

vertex-four wrote: post #4

m_eiman wrote: post #2

Doesn't this sound a lot like DNS-SD over mDNS?

I think it's centralised, so you don't need to either have all your machines on one subnet or configure your routers (if you can) to forward DNS-SD packets between all your subnets, probably creating a small broadcast storm at scale.

That's right, it's really just a plain ol DNS server that happens to read its records from Mesos.

Re: Service Discovery with Mesos-DNS

#8

Post by tknaup » Wed, Jan 21, 2015, 5:11 PM UTC

vidarh wrote: post #6

preillyme wrote: post #3

Awesome, Mesos-DNS is simple and stateless. Unlike Consul and SkyDNS, it does not require consensus mechanisms, persistent storage, or a replicated log. This is possible because Mesos-DNS does not implement heartbeats, health monitoring, or lifetime management for applications. This functionality is already available by the Mesos master, slaves, and frameworks.

The same is the case for SkyDNS2. It runs just fine against our Etcd backends. In both cases the combination (SkyDNS + Etcd or Consul) looks far less complicated than Mesos, so I don't really see what you think you gain. If you already have other reasons to want to run Mesos, sure.

They are simpler but keep it mind all the other things you get from running on Mesos, like provisioning your services, having your services restarted when they crash, workload migration when machines fail, bin-packing so you don't waste resources, etc.

Re: Service Discovery with Mesos-DNS

#9

Post by gtaylor » Wed, Jan 21, 2015, 5:58 PM UTC

I haven't yet had a chance to play with or research Mesosphere, but I'm hearing it mentioned more and more. Are its goals similar to that of CoreOS and/or Docker Swarm, in that we're slinging around services/containers rather than managing machines or VMs?

Re: Service Discovery with Mesos-DNS

#10

Post by kozyraki » Wed, Jan 21, 2015, 9:51 PM UTC

Thanks for the comments everybody. I am one of the people behind Mesos-DNS and will gladly answer any questions about it.

DNS is an obvious way to support many service discovery needs. There were two motivations for implementing Mesos-DNS instead of using another DNS system. First, we needed a DNS system that closely integrates with Mesos. Instead of having every user or framework describe tasks twice (once to Mesos for execution and once to a DNS system), it easier and cleaner to automatically pass task information from Mesos to DNS. Second, we wanted a simple solution. Mesos and its frameworks already implement fault tolerance and life cycle management. We did not want to force Mesos users to deploy another set of consensus mechanisms, persistent storage, or a replicated logs just for DNS.

One more interesting detail. SkyDNS, Consul, and Mesos-DNS use the great go-DNS library by Miek Gieben (github.com/miekg/dns). So, their core DNS capabilities are the same. They differ in what they offer for fault-tolerance, life cycle management, load balancing, etc. Mesos-DNS defers all this functionality to Mesos and its framework (KISS).