I have a few clarifications - The scope of the management process is not to simply run repair scheduling. Repair scheduling is one of the many features we could implement or adopt from existing sources. So could we please split the Management Process discussion and the repair scheduling? After re-reading the management process proposal, I see we missed to communicate a basic idea in the document. We wanted to take a pluggable approach to various activities that the management process could perform. This could accommodate different implementations of common activities such as repair. The management process would provide the basic framework and it would have default implementations for some of the basic activities. This would allow for speedier iteration cycles and keep things extensible. Turning to some questions that Jon and others have raised, when I +1, my intention is to fully contribute and stay with this community. That said, things feel rushed for some but for me it feels like analysis paralysis. We're looking for actionable feedback and to discuss the management process _not_ repair scheduling solutions. Thanks, Dinesh
On Sep 12, 2018, at 6:24 PM, sankalp kohli <kohlisank...@gmail.com> wrote: Here is a list of open discussion points from the voting thread. I think some are already answered but I will still gather these questions here. >From several people: 1. Vote is rushed and we need more time for discussion. >From Sylvain 2. About the voting process...I think that was addressed by Jeff Jirsa and deserves a separate thread as it is not directly related to this thread. 3. Does the project need a side car. >From Jonathan Haddad 4. Are people doing +1 willing to contribute >From Jonathan Ellis 5. List of feature set, maturity, maintainer availability from Reaper or any other project being donated. Mick Semb Wever 6. We should not vote on these things and instead build consensus. Open Questions from this thread 7. What technical debts we are talking about in Reaper. Can someone give concrete examples. 8. What is the timeline of donating Reaper to Apache Cassandra. On Wed, Sep 12, 2018 at 3:49 PM sankalp kohli <kohlisank...@gmail.com> wrote: (Using this thread and not the vote thread intentionally) For folks talking about vote being rushed. I would use the email from Joseph to show this is not rushed. There was no email on this thread for 4 months until I pinged. Dec 2016: Vinay worked with Jon and Alex to try to collaborate on Reaper to come up with design goals for a repair scheduler that could work at Netflix scale. ~Feb 2017: Netflix believes that the fundamental design gaps prevented us from using Reaper as it relies heavily on remote JMX connections and central coordination. Sep. 2017: Vinay gives a lightning talk at NGCC about a highly available and distributed repair scheduling sidecar/tool. He is encouraged by multiple committers to build repair scheduling into the daemon itself and not as a sidecar so the database is truly eventually consistent. ~Jun. 2017 - Feb. 2018: Based on internal need and the positive feedback at NGCC, Vinay and myself prototype the distributed repair scheduler within Priam and roll it out at Netflix scale. Mar. 2018: I open a Jira (CASSANDRA-14346) along with a detailed 20 page design document for adding repair scheduling to the daemon itself and open the design up for feedback from the community. We get feedback from Alex, Blake, Nate, Stefan, and Mick. As far as I know there were zero proposals to contribute Reaper at this point. We hear the consensus that the community would prefer repair scheduling in a separate distributed sidecar rather than in the daemon itself and we re-work the design to match this consensus, re-aligning with our original proposal at NGCC. Apr 2018: Blake brings the discussion of repair scheduling to the dev list ( https://lists.apache.org/thread.html/760fbef677f27aa5c2ab4c375c7efeb81304fea428deff986ba1c2eb@%3Cdev.cassandra.apache.org%3E ). Many community members give positive feedback that we should solve it as part of Cassandra and there is still no mention of contributing Reaper at this point. The last message is my attempted summary giving context on how we want to take the best of all the sidecars (OpsCenter, Priam, Reaper) and ship them with Cassandra. Apr. 2018: Dinesh opens CASSANDRA-14395 along with a public design document for gathering feedback on a general management sidecar. Sankalp and Dinesh encourage Vinay and myself to kickstart that sidecar using the repair scheduler patch Apr 2018: Dinesh reaches out to the dev list ( https://lists.apache.org/thread.html/a098341efd8f344494bcd2761dba5125e971b59b1dd54f282ffda253@%3Cdev.cassandra.apache.org%3E ) about the general management process to gain further feedback. All feedback remains positive as it is a potential place for multiple community members to contribute their various sidecar functionality. May-Jul 2017: Vinay and I work on creating a basic sidecar for running the repair scheduler based on the feedback from the community in CASSANDRA-14346 and CASSANDRA-14395 Jun 2018: I bump CASSANDRA-14346 indicating we're still working on this, nobody objects Jul 2018: Sankalp asks on the dev list if anyone has feature Jiras anyone needs review for before 4.0, I mention again that we've nearly got the basic sidecar and repair scheduling work done and will need help with review. No one responds. Aug 2018: We submit a patch that brings a basic distributed sidecar and robust distributed repair to Cassandra itself. Dinesh mentions that he will try to review. Now folks appear concerned about it being in tree and instead maybe it should go in a different repo all together. I don't think we have consensus on the repo choice yet. On Sun, Sep 9, 2018 at 9:13 AM sankalp kohli <kohlisank...@gmail.com> wrote: I agree with Jon and I think folks who are talking about tech debts in Reaper should elaborate with examples about these tech debts. Can we be more precise and list them down? I see it spread out over this long email thread!! On Sun, Sep 9, 2018 at 6:29 AM Elliott Sims <elli...@backblaze.com> wrote: A big one to add to your list there, IMO as a user: * API for determining detailed repair state (and history?). Essentially, something beyond just "Is some sort of repair running?" so that tools like Reaper can parallelize better. On Sun, Sep 9, 2018 at 8:30 AM, Stefan Podkowinski <s...@apache.org> wrote: Does it have to be a single project with functionality provided by multiple plugins? Designing a plugin API at this point seems to be a bit early and comes with additional complexity around managing plugins in general. I was more thinking into the direction of: "what can we do to enable people to create any kind of side car or tooling solution?". Thinks like: Common cluster discovery and management API * Detect local Cassandra processes * Discover and receive events on cluster topology * Get assigned tokens for nodes * Read node configuration * Health checks (as already proposed) Any side cars should be easy to install on nodes that already run Cassandra * Scripts for packaging (tar, deb, rpm) * Templates for systemd support, optionally with auto-startup dependency on the Cassandra main process Integration testing * Provide basic testing framework for mocking cluster state and messages Support for other languages / avoid having to use JMX * JMX bridge (HTTP? gRPC?, already implemented in #14346?) Obviously the whole side car discussion is not moving into a direction everyone's happy with. Would it be an option to take a step back and start implementing such a tooling framework with scripts and libraries for the features described above, as a small GitHub project, instead of putting an existing side-car solution up for vote? If that would work and we get people collaborating on code shared between existing side-cars, then we could take the next step and think about either revisit the "official Cassandra side-car" topic, or add the created client tooling framework as official sub-project to the Cassandra project (maybe via Apache incubator). On 08.09.18 02:49, Joseph Lynch wrote: On Fri, Sep 7, 2018 at 5:03 PM Jonathan Haddad <j...@jonhaddad.com> wrote: We haven’t even defined any requirements for an admin tool. It’s hard to make a case for anything without agreement on what we’re trying to build. We were/are trying to sketch out scope/requirements in the #14395 and #14346 tickets as well as their associated design documents. I think the general proposed direction is a distributed 1:1 management sidecar process similar in architecture to Netflix's Priam except explicitly built to be general and pluggable by anyone rather than tightly coupled to AWS. Dinesh, Vinay and I were aiming for low amounts of scope at first and take things in an iterative approach with just enough upfront design but not so much we are unable to make any progress at all. For example maybe something like: 1. Get a super simple and non controversial sidecar process that ships with Cassandra and exposes a lightweight HTTP interface to e.g. some basic JMX endpoints 2a. Add a pluggable execution engine for cron/oneshot/scheduled jobs with the basic interfaces and state store and such 2b. Start scoping and implementing the full HTTP interface, e.g. backup status, cluster health status, etc ... 3a. Start integrating implementations of the jobs from 2a such as snapshot, backup, cluster restart, daemon + sstable upgrade, repair, etc 3b. Start integrating UI components that pair with the HTTP interface from 2b 4. ?? Perhaps start unlocking next generation operations like moving "background" activities like compaction, streaming, repair etc into one or more sidecar contained processes to ensure the main daemon only handles read+write requests There are going to be a lot of questions to answer, and I think trying to answer them all up front will mean that we get nowhere or make unfortunate compromises that cripple the project from the start. If people think we need to do more design and discussion than we have been doing then we can spend more time on the design, but personally I'd rather start iterating on code and prove value incrementally. If it doesn't work out we won't release it GA to the community ... -Joey --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@cassandra.apache.org For additional commands, e-mail: dev-h...@cassandra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@cassandra.apache.org For additional commands, e-mail: dev-h...@cassandra.apache.org
