Hi Hao It seems that I misunderstood the background of usage for your cases. High availability configuration targets for fault tolerance not for general development evolution. If you want to change your job topology, just follow the general rule to restore from savepoint/checkpoint, do not rely on HA to do job migration things.
Best Yun Tang ________________________________ From: Hao Sun <ha...@zendesk.com> Sent: Friday, October 11, 2019 8:33 To: Yun Tang <myas...@live.com> Cc: Vijay Bhaskar <bhaskar.eba...@gmail.com>; Yang Wang <danrtsey...@gmail.com>; Sean Hester <sean.hes...@bettercloud.com>; Aleksandar Mastilovic <amastilo...@sightmachine.com>; Yuval Itzchakov <yuva...@gmail.com>; user <user@flink.apache.org> Subject: Re: Challenges Deploying Flink With Savepoints On Kubernetes Yep I know that option. That's where get me confused as well. In a HA setup, where do I supply this option (allowNonRestoredState)? This option requires a savepoint path when I start a flink job I remember. And HA does not require the path Hao Sun On Thu, Oct 10, 2019 at 11:16 AM Yun Tang <myas...@live.com<mailto:myas...@live.com>> wrote: Just a minor supplement @Hao Sun<mailto:ha...@zendesk.com>, if you decided to drop a operator, don't forget to add --allowNonRestoredState (short: -n) option [1] [1] https://ci.apache.org/projects/flink/flink-docs-stable/ops/state/savepoints.html#allowing-non-restored-state Best Yun Tang ________________________________ From: Vijay Bhaskar <bhaskar.eba...@gmail.com<mailto:bhaskar.eba...@gmail.com>> Sent: Thursday, October 10, 2019 19:24 To: Yang Wang <danrtsey...@gmail.com<mailto:danrtsey...@gmail.com>> Cc: Sean Hester <sean.hes...@bettercloud.com<mailto:sean.hes...@bettercloud.com>>; Aleksandar Mastilovic <amastilo...@sightmachine.com<mailto:amastilo...@sightmachine.com>>; Yun Tang <myas...@live.com<mailto:myas...@live.com>>; Hao Sun <ha...@zendesk.com<mailto:ha...@zendesk.com>>; Yuval Itzchakov <yuva...@gmail.com<mailto:yuva...@gmail.com>>; user <user@flink.apache.org<mailto:user@flink.apache.org>> Subject: Re: Challenges Deploying Flink With Savepoints On Kubernetes Thanks Yang. We will try and let you know if any issues arise Regards Bhaskar On Thu, Oct 10, 2019 at 1:53 PM Yang Wang <danrtsey...@gmail.com<mailto:danrtsey...@gmail.com>> wrote: @ Hao Sun, I have made a confirmation that even we change parallelism and/or modify operators, add new operators, the flink cluster could also recover from latest checkpoint. @ Vijay a) Some individual jobmanager/taskmanager crashed exceptionally(someother jobmanagers and taskmanagers are alive), it could recover from the latest checkpoint. b) All jobmanagers and taskmanagers fails, it could still recover from the latest checkpoint if the cluster-id is not changed. When we enable the HA, The meta of jobgraph and checkpoint is saved on zookeeper and the real files are save on high-availability storage(HDFS). So when the flink application is submitted again with same cluster-id, it could recover jobs and checkpoint from zookeeper. I think it has been supported for a long time. Maybe you could have a try with flink-1.8 or 1.9. Best, Yang Vijay Bhaskar <bhaskar.eba...@gmail.com<mailto:bhaskar.eba...@gmail.com>> 于2019年10月10日周四 下午2:26写道： Thanks Yang and Sean. I have couple of questions: 1) Suppose the scenario of , bringing back entire cluster, a) In that case, at least one job manager out of HA group should be up and running right? or b) All the job managers fails, then also this works? In that case please let me know the procedure/share the documentation? How to start from previous check point? What Flink version onwards this feature is stable? Regards Bhaskar On Wed, Oct 9, 2019 at 8:51 AM Yang Wang <danrtsey...@gmail.com<mailto:danrtsey...@gmail.com>> wrote: Hi Vijay, If you are using HA solution, i think you do not need to specify the savepoint. Instead the checkpoint is used. The checkpoint is done automatically and periodically based on your configuration.When the jobmanager/taskmanager fails or the whole cluster crashes, it could always recover from the latest checkpoint. Does this meed your requirement? Best, Yang Sean Hester <sean.hes...@bettercloud.com<mailto:sean.hes...@bettercloud.com>> 于2019年10月1日周二 上午1:47写道： Vijay, That is my understanding as well: the HA solution only solves the problem up to the point all job managers fail/restart at the same time. That's where my original concern was. But to Aleksandar and Yun's point, running in HA with 2 or 3 Job Managers per cluster--as long as they are all deployed to separate GKE nodes--would provide a very high uptime/low failure rate, at least on paper. It's a promising enough option that we're going to run in HA for a month or two and monitor results before we put in any extra work to customize the savepoint start-up behavior. On Fri, Sep 27, 2019 at 2:24 AM Vijay Bhaskar <bhaskar.eba...@gmail.com<mailto:bhaskar.eba...@gmail.com>> wrote: I don't think HA will help to recover from cluster crash, for that we should take periodic savepoint right? Please correct me in case i am wrong Regards Bhaskar On Fri, Sep 27, 2019 at 11:48 AM Vijay Bhaskar <bhaskar.eba...@gmail.com<mailto:bhaskar.eba...@gmail.com>> wrote: Suppose my cluster got crashed and need to bring up the entire cluster back? Does HA still helps to run the cluster from latest save point? Regards Bhaskar On Thu, Sep 26, 2019 at 7:44 PM Sean Hester <sean.hes...@bettercloud.com<mailto:sean.hes...@bettercloud.com>> wrote: thanks to everyone for all the replies. i think the original concern here with "just" relying on the HA option is that there are some disaster recovery and data center migration use cases where the continuity of the job managers is difficult to preserve. but those are admittedly very edgy use cases. i think it's definitely worth reviewing the SLAs with our site reliability engineers to see how likely it would be to completely lose all job managers under an HA configuration. that small a risk might be acceptable/preferable to a one-off solution. @Aleksander, would love to learn more about Zookeeper-less HA. i think i spotted a thread somewhere between Till and someone (perhaps you) about that. feel free to DM me. thanks again to everyone! On Thu, Sep 26, 2019 at 7:32 AM Yang Wang <danrtsey...@gmail.com<mailto:danrtsey...@gmail.com>> wrote: Hi, Aleksandar Savepoint option in standalone job cluster is optional. If you want to always recover from the latest checkpoint, just as Aleksandar and Yun Tang said you could use the high-availability configuration. Make sure the cluster-id is not changed, i think the job could recover both at exceptionally crash and restart by expectation. @Aleksandar Mastilovic<mailto:amastilo...@sightmachine.com>, we are also have an zookeeper-less high-availability implementation[1]. Maybe we could have some discussion and contribute this useful feature to the community. [1]. https://docs.google.com/document/d/1Z-VdJlPPEQoWT1WLm5woM4y0bFep4FrgdJ9ipQuRv8g/edit Best, Yang Aleksandar Mastilovic <amastilo...@sightmachine.com<mailto:amastilo...@sightmachine.com>> 于2019年9月26日周四 上午4:11写道： Would you guys (Flink devs) be interested in our solution for zookeeper-less HA? I could ask the managers how they feel about open-sourcing the improvement. On Sep 25, 2019, at 11:49 AM, Yun Tang <myas...@live.com<mailto:myas...@live.com>> wrote: As Aleksandar said, k8s with HA configuration could solve your problem. There already have some discussion about how to implement such HA in k8s if we don't have a zookeeper service: FLINK-11105 [1] and FLINK-12884 [2]. Currently, you might only have to choose zookeeper as high-availability service. [1] https://issues.apache.org/jira/browse/FLINK-11105 [2] https://issues.apache.org/jira/browse/FLINK-12884 Best Yun Tang ________________________________ From: Aleksandar Mastilovic <amastilo...@sightmachine.com<mailto:amastilo...@sightmachine.com>> Sent: Thursday, September 26, 2019 1:57 To: Sean Hester <sean.hes...@bettercloud.com<mailto:sean.hes...@bettercloud.com>> Cc: Hao Sun <ha...@zendesk.com<mailto:ha...@zendesk.com>>; Yuval Itzchakov <yuva...@gmail.com<mailto:yuva...@gmail.com>>; user <user@flink.apache.org<mailto:user@flink.apache.org>> Subject: Re: Challenges Deploying Flink With Savepoints On Kubernetes Can’t you simply use JobManager in HA mode? It would pick up where it left off if you don’t provide a Savepoint. On Sep 25, 2019, at 6:07 AM, Sean Hester <sean.hes...@bettercloud.com<mailto:sean.hes...@bettercloud.com>> wrote: thanks for all replies! i'll definitely take a look at the Flink k8s Operator project. i'll try to restate the issue to clarify. this issue is specific to starting a job from a savepoint in job-cluster mode. in these cases the Job Manager container is configured to run a single Flink job at start-up. the savepoint needs to be provided as an argument to the entrypoint. the Flink documentation for this approach is here: https://github.com/apache/flink/tree/master/flink-container/kubernetes#resuming-from-a-savepoint the issue is that taking this approach means that the job will always start from the savepoint provided as the start argument in the Kubernetes YAML. this includes unplanned restarts of the job manager, but we'd really prefer any unplanned restarts resume for the most recent checkpoint instead of restarting from the configured savepoint. so in a sense we want the savepoint argument to be transient, only being used during the initial deployment, but this runs counter to the design of Kubernetes which always wants to restore a deployment to the "goal state" as defined in the YAML. i hope this helps. if you want more details please let me know, and thanks again for your time. On Tue, Sep 24, 2019 at 1:09 PM Hao Sun <ha...@zendesk.com<mailto:ha...@zendesk.com>> wrote: I think I overlooked it. Good point. I am using Redis to save the path to my savepoint, I might be able to set a TTL to avoid such issue. Hao Sun On Tue, Sep 24, 2019 at 9:54 AM Yuval Itzchakov <yuva...@gmail.com<mailto:yuva...@gmail.com>> wrote: Hi Hao, I think he's exactly talking about the usecase where the JM/TM restart and they come back up from the latest savepoint which might be stale by that time. On Tue, 24 Sep 2019, 19:24 Hao Sun, <ha...@zendesk.com<mailto:ha...@zendesk.com>> wrote: We always make a savepoint before we shutdown the job-cluster. So the savepoint is always the latest. When we fix a bug or change the job graph, it can resume well. We only use checkpoints for unplanned downtime, e.g. K8S killed JM/TM, uncaught exception, etc. Maybe I do not understand your use case well, I do not see a need to start from checkpoint after a bug fix. >From what I know, currently you can use checkpoint as a savepoint as well Hao Sun On Tue, Sep 24, 2019 at 7:48 AM Yuval Itzchakov <yuva...@gmail.com<mailto:yuva...@gmail.com>> wrote: AFAIK there's currently nothing implemented to solve this problem, but working on a possible fix can be implemented on top of https://github.com/lyft/flinkk8soperator which already has a pretty fancy state machine for rolling upgrades. I'd love to be involved as this is an issue I've been thinking about as well. Yuval On Tue, Sep 24, 2019 at 5:02 PM Sean Hester <sean.hes...@bettercloud.com<mailto:sean.hes...@bettercloud.com>> wrote: hi all--we've run into a gap (knowledge? design? tbd?) for our use cases when deploying Flink jobs to start from savepoints using the job-cluster mode in Kubernetes. we're running a ~15 different jobs, all in job-cluster mode, using a mix of Flink 1.8.1 and 1.9.0, under GKE (Google Kubernetes Engine). these are all long-running streaming jobs, all essentially acting as microservices. we're using Helm charts to configure all of our deployments. we have a number of use cases where we want to restart jobs from a savepoint to replay recent events, i.e. when we've enhanced the job logic or fixed a bug. but after the deployment we want to have the job resume it's "long-running" behavior, where any unplanned restarts resume from the latest checkpoint. the issue we run into is that any obvious/standard/idiomatic Kubernetes deployment includes the savepoint argument in the configuration. if the Job Manager container(s) have an unplanned restart, when they come back up they will start from the savepoint instead of resuming from the latest checkpoint. everything is working as configured, but that's not exactly what we want. we want the savepoint argument to be transient somehow (only used during the initial deployment), but Kubernetes doesn't really support the concept of transient configuration. i can see a couple of potential solutions that either involve custom code in the jobs or custom logic in the container (i.e. a custom entrypoint script that records that the configured savepoint has already been used in a file on a persistent volume or GCS, and potentially when/why/by which deployment). but these seem like unexpected and hacky solutions. before we head down that road i wanted to ask: * is this is already a solved problem that i've missed? * is this issue already on the community's radar? thanks in advance! -- Sean Hester | Senior Staff Software Engineer | m. 404-828-0865 3525 Piedmont Rd. NE, Building 6, Suite 500, Atlanta, GA 30305 <http://www.bettercloud.com/>[https://www.bettercloud.com/monitor/wp-content/uploads/sites/3/2016/12/bettercloud-emaillogo.png]<http://www.bettercloud.com/> Altitude 2019 in San Francisco | Sept. 23 - 25 It’s not just an IT conference, it’s “a complete learning and networking experience”<https://altitude.bettercloud.com/?utm_source=gmail&utm_medium=signature&utm_campaign=2019-altitude> -- Best Regards, Yuval Itzchakov. -- Sean Hester | Senior Staff Software Engineer | m. 404-828-0865 3525 Piedmont Rd. 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