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
