Hi Thomas Weise, I am not sure why this change will break the existing K8s/container-based setup. Since it will output the logs to stdout and log files at the same time, you could still use the `kubectl logs` to view the logs. And log collection could just work as before.
What we could benefit from this is the logs could also be accessed via Flink web dashboard. I think it is more convenient when the users do not have the permissions to execute `kubectl`. @Till Rohrmann <trohrm...@apache.org>, it will be great if we could use tee to side output logs to file and avoid duplication. I will have a look. Best, Yang Thomas Weise <t...@apache.org> 于2020年5月6日周三 上午1:40写道： > The downside of change to the default behavior is the breakage of existing > k8s or other container-based production setups. > > Logs that are emitted to stdout are visible through kubectl logs and > infrastructure is setup for log collection. > > Thanks, > Thomas > > > On Tue, May 5, 2020 at 6:31 AM Arvid Heise <ar...@ververica.com> wrote: > > > From my previous experience with K8s, I'd assume that the cluster itself > > already has some ELK attached to it and all stdout/err is collected > > automatically. > > > > So if you want to also add logs, I'd make that configurable and I'm torn > > what the default should be as both make sense. > > > > However, thinking a bit further, it sounds as if the current way is > already > > very inconsistent. We should probably either have log files for > everything > > or log everything to stdout/err and let K8s deal with it. And then we > > should have some configuration to toggle between the modes. > > > > On Tue, May 5, 2020 at 2:50 PM Stephan Ewen <se...@apache.org> wrote: > > > > > @Patrick could you chime in? > > > > > > We should at least understand the original motivation before simply > > > changing the way it works. > > > > > > On Tue, May 5, 2020 at 2:49 PM Stephan Ewen <se...@apache.org> wrote: > > > > > > > I think Patrick originally introduced the foreground mode, and I > > believe > > > > it had indeed something to do with container use and logging. > > > > > > > > IIRC the default assumption in docker and Kubernetes is that the logs > > > come > > > > on stdout (or stderr) so after "principle of least astonishment" the > > idea > > > > was to give a similar experience with Flink. > > > > > > > > On Tue, May 5, 2020 at 10:49 AM David Anderson < > da...@alpinegizmo.com> > > > > wrote: > > > > > > > >> I like this idea because it should improve the experience (and > reduce > > > >> confusion) for folks having their first flink experience via one of > > the > > > >> docker playgrounds. Right now it gives the impression that something > > is > > > >> broken out-of-the-box. > > > >> > > > >> Regards, > > > >> David > > > >> > > > >> On Mon, May 4, 2020 at 6:01 PM Till Rohrmann <trohrm...@apache.org> > > > >> wrote: > > > >> > > > >> > Hi everyone, > > > >> > > > > >> > thanks for starting this discussion Chesnay. > > > >> > > > > >> > I think it would be nice if we also displayed the logs when > starting > > > the > > > >> > process in the foreground. > > > >> > > > > >> > The repercussions could be mitigated if the default logger > > > >> configurations > > > >> > would contain file rolling with a max log file size. > > > >> > > > > >> > @Yang I think there are solutions how to redirect stdout and > stderr > > > into > > > >> > separate files using tee without duplication [1]. > > > >> > > > > >> > [1] http://www.softpanorama.org/Tools/tee.shtml > > > >> > > > > >> > Cheers, > > > >> > Till > > > >> > > > > >> > On Wed, Apr 29, 2020 at 4:28 AM Yang Wang <danrtsey...@gmail.com> > > > >> wrote: > > > >> > > > > >> > > Thanks for Chesnay starting this discussion. > > > >> > > > > > >> > > In FLINK-17166 implementation[1], we are trying to use "tee" > > instead > > > >> of > > > >> > > introducing the stream redirection(redirect the out/err to > files). > > > >> > However, > > > >> > > a side effect is that the logging will be duplicated both in > .log > > > and > > > >> > .out > > > >> > > files. > > > >> > > Then it may consume more disk space. However it is not a very > > > critical > > > >> > > problem since we could use log4j/logback configuration to > control > > > the > > > >> > > rolling > > > >> > > files and max size. > > > >> > > > > > >> > > Also, it only happens in docker/K8s deployment. For YARN/Mesos > > > >> > deployment, > > > >> > > the behavior is just same as before. > > > >> > > > > > >> > > > > > >> > > [1]. https://github.com/apache/flink/pull/11839 > > > >> > > > > > >> > > Best, > > > >> > > Yang > > > >> > > > > > >> > > Chesnay Schepler <ches...@apache.org> 于2020年4月29日周三 上午12:30写道： > > > >> > > > > > >> > > > Currently, processes started in the foreground (like in the > case > > > of > > > >> > > > Docker) output all logging/stdout directly to the console, > > without > > > >> > > > creating any logging files. > > > >> > > > > > > >> > > > The downside of this approach, as outlined in FLIP-111, is > that > > > the > > > >> > > > WebUI is not able to display the logs since it relies on these > > > very > > > >> > > > files to exist. > > > >> > > > > > > >> > > > In FLINK-17166 (part of FLIP-111) we are trying to change this > > > such > > > >> > that > > > >> > > > we always created .log/.out files. It seems like a reasonable > > > >> change to > > > >> > > > do, but it could have repercussions on existing deployments > > since > > > we > > > >> > > > will naturally use more disk space (logs gotta go somewhere). > > > >> > > > > > > >> > > > I'm curious what people think about this. > > > >> > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > > > > > > > > > > > -- > > > > Arvid Heise | Senior Java Developer > > > > <https://www.ververica.com/> > > > > Follow us @VervericaData > > > > -- > > > > Join Flink Forward <https://flink-forward.org/> - The Apache Flink > > Conference > > > > Stream Processing | Event Driven | Real Time > > > > -- > > > > Ververica GmbH | Invalidenstrasse 115, 10115 Berlin, Germany > > > > -- > > Ververica GmbH > > Registered at Amtsgericht Charlottenburg: HRB 158244 B > > Managing Directors: Timothy Alexander Steinert, Yip Park Tung Jason, Ji > > (Toni) Cheng > > >
