Hey Dave (and the group),
I have to say for me it was a little fiddly to upgrade a 0.18.2
cluster to 0.19.0. Largely because of a requirement to bring
everything back up in a certain order (I had to lower the quorum count
to 1) otherwise mesos failed to get a majority vote to initialise the
log (I had 3 masters).
I'd also be very interested in a zookeeper implementation - and
perhaps some improved documentation around the log.
Cheers,
Tom.
> On 13 Jun 2014, at 08:17, Dick Davies <d...@hellooperator.net> wrote:
>
> I thought I read that there was going to be a registry implementation
> backed by zookeeper;
> does anyone know why that was dropped?
>
> Really excited to see the containerizer features rolling in, but the
> quorum looks at first glance
> to make Mesos a little harder to operate
> ("This means adding or removing masters must be done carefully! ") - I
> understand the
> benefits but was hoping we could get by with the zookeeper registry.
>
>
>> On 13 June 2014 03:49, Dave Lester <daveles...@gmail.com> wrote:
>> Hi All,
>>
>> Below is a blog post that Ben Mahler wrote as release manager for Mesos
>> 0.19.0; it was published on the Mesos site today.
>>
>> I know that not everyone follows @ApacheMesos Twitter (even though you
>> should!), so I wanted to make sure was also shared on the user@ list.
>>
>> Cheers,
>> Dave
>>
>>
>> Apache Mesos 0.19.0 Released
>>
>> The latest Mesos release, 0.19.0 is now available for download. This new
>> version includes the following features and improvements:
>>
>> The master now persists the list of registered slaves in a durable
>> replicated manner using the Registrar and the replicated log.
>> Alpha support for custom container technologies has been added with the
>> ExternalContainerizer.
>> Metrics reporting has been overhauled and is now exposed on
>> <ip:port>/metrics/snapshot.
>> Slave Authentication: optionally, only authenticated slaves can register
>> with the master.
>> Numerous bug fixes and stability improvements.
>>
>> Full release notes are available on JIRA.
>>
>> Registrar
>>
>> Mesos 0.19.0 introduces the “Registrar”: the master now persists the list of
>> registered slaves in a durable replicated manner. The previous lack of
>> durable state was an intentional design decision that simplified failover
>> and allowed masters to be run and migrated with ease. However, the stateless
>> design had issues:
>>
>> In the event of a dual failure (slave fails while master is down), no lost
>> task notifications are sent. This leads to a task running according to the
>> framework but unknown to Mesos.
>> When a new master is elected, we may allow rogue slaves to re-register with
>> the master. This leads to tasks running on the slave that are not known to
>> the framework.
>>
>> Persisting the list of registered slaves allows failed over masters to
>> detect slaves that do not re-register, and notify frameworks accordingly. It
>> also allows us to prevent rogue slaves from re-registering; terminating the
>> rogue tasks in the process.
>>
>> The state is persisted using the replicated log (available since 0.9.0).
>>
>> External Containerization
>>
>> As alluded to during the containerization / isolation refactor in 0.18.0,
>> the ExternalContainerizer has landed in this release. This provides alpha
>> level support for custom containerization.
>>
>> Developers can implement their own external containerizers to provide
>> support for custom container technologies. Initial Docker support is now
>> available through some community driven external containerizers: Docker
>> Containerizer for Mesos by Tom Arnfeld and Deimos by Jason Dusek. Please
>> reach out on the mailing lists with questions!
>>
>> Metrics
>>
>> Previously, Mesos components had to use custom metrics code and custom HTTP
>> endpoints for exposing metrics. This made it difficult to expose additional
>> system metrics and often required having an endpoint for each libprocess
>> Process (Actor) for which metrics were desired. Having metrics spread across
>> endpoints was operationally complex.
>>
>> We needed a consistent, simple, and global way to expose metrics, which led
>> to the creation of a metrics library within libprocess. All metrics are now
>> exposed via /metrics/snapshot. The /stats.json endpoint remains for
>> backwards compatibility.
>>
>> Upgrading
>>
>> For backwards compatibility, the “Registrar” will be enabled in a phased
>> manner. By default, the “Registrar” is write-only in 0.19.0 and will be
>> read/write in 0.20.0.
>>
>> If running in high-availability mode with ZooKeeper, operators must now
>> specify the --work_dir for the master, along with the --quorum size of the
>> ensemble of masters. This means adding or removing masters must be done
>> carefully! The best practice is to only ever add or remove a single master
>> at a time and to allow a small amount of time for the replicated log to
>> catch up on the new master. Maintenance documentation will be added to
>> reflect this.
>>
>> Please refer to the upgrades document, which details how to perform an
>> upgrade from 0.18.x.
>>
>> Future Work
>>
>> Thanks to the Registrar, reconciliation primitives can now be provided to
>> ensure that the state of tasks between Mesos and frameworks is kept
>> consistent. This will remove the need for frameworks to implement
>> out-of-band task reconciliation to inspect the state of slaves.
>> Reconciliation work is being tracked at MESOS-1407.
>>
>> The addition of state through the Registrar opens up a rich set of possible
>> features that were previously not possible due to the lack of persistent
>> state in the master. These include:
>>
>> Cluster maintenance primitives (MESOS-1474)
>> Repair automation (MESOS-695)
>> Global resource reservations
>>
>> Getting Involved
>>
>> We encourage you to try out this release, and let us know what you think and
>> if you hit any issues on the user mailing list. You can also get in touch
>> with us via @ApacheMesos or via mailing lists and IRC.
>>
>> Thanks
>>
>> Thanks to the 32 contributors who made 0.19.0 possible:
>>
>> Ashutosh Jain, Adam B, Alexandra Sava, Anton Lindström, Archana kumari,
>> Benjamin Hindman, Benjamin Mahler, Bernardo Gomez Palacio, Bernd Mathiske,
>> Charlie Carson, Chengwei Yang, Chi Zhang, Dave Lester, Dominic Hamon, Ian
>> Downes, Isabel Jimenez, Jake Farrell, Jameel, Al-Aziz, Jiang Yan Xu, Jie Yu,
>> Nikita Vetoshkin, Niklas Q. Nielsen, Ritwik Yadav, Sam Taha, Steven Phung,
>> Till Toenshoff, Timothy St. Clair, Tobi Knaup, Tom Arnfeld, Tom Galloway,
>> Vinod Kone, Vinson Lee
