Hi Yang and Till, Thanks a lot for the help! I have the similar question as Till mentioned, if we do not fail Flink pods when the restart strategy is exhausted, it might be hard to monitor such failures. Today I get alerts if the k8s pods are restarted or in crash loop, but if this will no longer be the case, how can we deal with the monitoring? In production, I have hundreds of small flink jobs running (2-8 TM pods) doing stateless processing, it is really hard for us to expose ingress for each JM rest endpoint to periodically query the job status for each flink job.
Thanks a lot! Eleanore On Wed, Aug 5, 2020 at 4:56 AM Till Rohrmann <trohrm...@apache.org> wrote: > You are right Yang Wang. > > Thanks for creating this issue. > > Cheers, > Till > > On Wed, Aug 5, 2020 at 1:33 PM Yang Wang <danrtsey...@gmail.com> wrote: > >> Actually, the application status shows in YARN web UI is not determined >> by the jobmanager process exit code. >> Instead, we use "resourceManagerClient.unregisterApplicationMaster" to >> control the final status of YARN application. >> So although jobmanager exit with zero code, it still could show failed >> status in YARN web UI. >> >> I have created a ticket to track this improvement[1]. >> >> [1]. https://issues.apache.org/jira/browse/FLINK-18828 >> >> >> Best, >> Yang >> >> >> Till Rohrmann <trohrm...@apache.org> 于2020年8月5日周三 下午3:56写道： >> >>> Yes for the other deployments it is not a problem. A reason why people >>> preferred non-zero exit codes in case of FAILED jobs is that this is easier >>> to monitor than having to take a look at the actual job result. Moreover, >>> in the YARN web UI the application shows as failed if I am not mistaken. >>> However, from a framework's perspective, a FAILED job does not mean that >>> Flink has failed and, hence, the return code could still be 0 in my opinion. >>> >>> Cheers, >>> Till >>> >>> On Wed, Aug 5, 2020 at 9:30 AM Yang Wang <danrtsey...@gmail.com> wrote: >>> >>>> Hi Eleanore, >>>> >>>> Yes, I suggest to use Job to replace Deployment. It could be used >>>> to run jobmanager one time and finish after a successful/failed completion. >>>> >>>> However, using Job still could not solve your problem completely. Just >>>> as Till said, When a job exhausts the restart strategy, the jobmanager >>>> pod will terminate with non-zero exit code. It will cause the K8s >>>> restarting it again. Even though we could set the resartPolicy and >>>> backoffLimit, >>>> this is not a clean and correct way to go. We should terminate the >>>> jobmanager process with zero exit code in such situation. >>>> >>>> @Till Rohrmann <trohrm...@apache.org> I just have one concern. Is it a >>>> special case for K8s deployment? For standalone/Yarn/Mesos, it seems that >>>> terminating with >>>> non-zero exit code is harmless. >>>> >>>> >>>> Best, >>>> Yang >>>> >>>> Eleanore Jin <eleanore....@gmail.com> 于2020年8月4日周二 下午11:54写道： >>>> >>>>> Hi Yang & Till, >>>>> >>>>> Thanks for your prompt reply! >>>>> >>>>> Yang, regarding your question, I am actually not using k8s job, as I >>>>> put my app.jar and its dependencies under flink's lib directory. I have 1 >>>>> k8s deployment for job manager, and 1 k8s deployment for task manager, and >>>>> 1 k8s service for job manager. >>>>> >>>>> As you mentioned above, if flink job is marked as failed, it will >>>>> cause the job manager pod to be restarted. Which is not the ideal >>>>> behavior. >>>>> >>>>> Do you suggest that I should change the deployment strategy from using >>>>> k8s deployment to k8s job? In case the flink program exit with non-zero >>>>> code (e.g. exhausted number of configured restart), pod can be marked as >>>>> complete hence not restarting the job again? >>>>> >>>>> Thanks a lot! >>>>> Eleanore >>>>> >>>>> On Tue, Aug 4, 2020 at 2:49 AM Yang Wang <danrtsey...@gmail.com> >>>>> wrote: >>>>> >>>>>> @Till Rohrmann <trohrm...@apache.org> In native mode, when a Flink >>>>>> application terminates with FAILED state, all the resources will be >>>>>> cleaned >>>>>> up. >>>>>> >>>>>> However, in standalone mode, I agree with you that we need to rethink >>>>>> the exit code of Flink. When a job exhausts the restart >>>>>> strategy, we should terminate the pod and do not restart again. After >>>>>> googling, it seems that we could not specify the restartPolicy >>>>>> based on exit code[1]. So maybe we need to return a zero exit code to >>>>>> avoid restarting by K8s. >>>>>> >>>>>> [1]. >>>>>> https://stackoverflow.com/questions/48797297/is-it-possible-to-define-restartpolicy-based-on-container-exit-code >>>>>> >>>>>> Best, >>>>>> Yang >>>>>> >>>>>> Till Rohrmann <trohrm...@apache.org> 于2020年8月4日周二 下午3:48写道： >>>>>> >>>>>>> @Yang Wang <danrtsey...@gmail.com> I believe that we should >>>>>>> rethink the exit codes of Flink. In general you want K8s to restart a >>>>>>> failed Flink process. Hence, an application which terminates in state >>>>>>> FAILED should not return a non-zero exit code because it is a valid >>>>>>> termination state. >>>>>>> >>>>>>> Cheers, >>>>>>> Till >>>>>>> >>>>>>> On Tue, Aug 4, 2020 at 8:55 AM Yang Wang <danrtsey...@gmail.com> >>>>>>> wrote: >>>>>>> >>>>>>>> Hi Eleanore, >>>>>>>> >>>>>>>> I think you are using K8s resource "Job" to deploy the jobmanager. >>>>>>>> Please set .spec.template.spec.restartPolicy = "Never" and >>>>>>>> spec.backoffLimit = 0. >>>>>>>> Refer here[1] for more information. >>>>>>>> >>>>>>>> Then, when the jobmanager failed because of any reason, the K8s job >>>>>>>> will be marked failed. And K8s will not restart the job again. >>>>>>>> >>>>>>>> [1]. >>>>>>>> https://kubernetes.io/docs/concepts/workloads/controllers/job/#job-termination-and-cleanup >>>>>>>> >>>>>>>> >>>>>>>> Best, >>>>>>>> Yang >>>>>>>> >>>>>>>> Eleanore Jin <eleanore....@gmail.com> 于2020年8月4日周二 上午12:05写道： >>>>>>>> >>>>>>>>> Hi Till, >>>>>>>>> >>>>>>>>> Thanks for the reply! >>>>>>>>> >>>>>>>>> I manually deploy as per-job mode [1] and I am using Flink 1.8.2. >>>>>>>>> Specifically, I build a custom docker image, which I copied the app >>>>>>>>> jar >>>>>>>>> (not uber jar) and all its dependencies under /flink/lib. >>>>>>>>> >>>>>>>>> So my question is more like, in this case, if the job is marked as >>>>>>>>> FAILED, which causes k8s to restart the pod, this seems not help at >>>>>>>>> all, >>>>>>>>> what are the suggestions for such scenario? >>>>>>>>> >>>>>>>>> Thanks a lot! >>>>>>>>> Eleanore >>>>>>>>> >>>>>>>>> [1] >>>>>>>>> https://ci.apache.org/projects/flink/flink-docs-release-1.8/ops/deployment/kubernetes.html#flink-job-cluster-on-kubernetes >>>>>>>>> >>>>>>>>> On Mon, Aug 3, 2020 at 2:13 AM Till Rohrmann <trohrm...@apache.org> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> Hi Eleanore, >>>>>>>>>> >>>>>>>>>> how are you deploying Flink exactly? Are you using the >>>>>>>>>> application mode with native K8s support to deploy a cluster [1] or >>>>>>>>>> are you >>>>>>>>>> manually deploying a per-job mode [2]? >>>>>>>>>> >>>>>>>>>> I believe the problem might be that we terminate the Flink >>>>>>>>>> process with a non-zero exit code if the job reaches the >>>>>>>>>> ApplicationStatus.FAILED [3]. >>>>>>>>>> >>>>>>>>>> cc Yang Wang have you observed a similar behavior when running >>>>>>>>>> Flink in per-job mode on K8s? >>>>>>>>>> >>>>>>>>>> [1] >>>>>>>>>> https://ci.apache.org/projects/flink/flink-docs-release-1.11/ops/deployment/native_kubernetes.html#flink-kubernetes-application >>>>>>>>>> [2] >>>>>>>>>> https://ci.apache.org/projects/flink/flink-docs-release-1.11/ops/deployment/kubernetes.html#job-cluster-resource-definitions >>>>>>>>>> [3] >>>>>>>>>> https://github.com/apache/flink/blob/master/flink-runtime/src/main/java/org/apache/flink/runtime/clusterframework/ApplicationStatus.java#L32 >>>>>>>>>> >>>>>>>>>> On Fri, Jul 31, 2020 at 6:26 PM Eleanore Jin < >>>>>>>>>> eleanore....@gmail.com> wrote: >>>>>>>>>> >>>>>>>>>>> Hi Experts, >>>>>>>>>>> >>>>>>>>>>> I have a flink cluster (per job mode) running on kubernetes. The >>>>>>>>>>> job is configured with restart strategy >>>>>>>>>>> >>>>>>>>>>> restart-strategy.fixed-delay.attempts: >>>>>>>>>>> 3restart-strategy.fixed-delay.delay: 10 s >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> So after 3 times retry, the job will be marked as FAILED, hence >>>>>>>>>>> the pods are not running. However, kubernetes will then restart the >>>>>>>>>>> job >>>>>>>>>>> again as the available replicas do not match the desired one. >>>>>>>>>>> >>>>>>>>>>> I wonder what are the suggestions for such a scenario? How >>>>>>>>>>> should I configure the flink job running on k8s? >>>>>>>>>>> >>>>>>>>>>> Thanks a lot! >>>>>>>>>>> Eleanore >>>>>>>>>>> >>>>>>>>>>
