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Re: [DISCUSS] CloudStack graceful shutdown


Rafael

> * Regarding the tasks/jobs that management servers (MSs) execute; are
these
tasks originate from requests that come to the MS, or is it possible that
requests received by one management server to be executed by other? I mean,
if I execute a request against MS1, will this request always be
executed/threated by MS1, or is it possible that this request is executed
by another MS (e.g. MS2)?

Yes its possible, but it will be tracked under async_job with proper MS
that is responsible for this task.

My initial goal was to prevent user from creating more async jobs on the
node thats about to go down for maintenance - but as i'm thinking about it
- i dont know if it matters - since async job will be executed on the MS
node that tracks a specific hypervisor/agent - as defined in cloud.host
table.

Maybe i'll leave off the blocking off 8080/8443 and just focus on tracking
async_jobs instead. Assuming you are managing your MS with Load Balancer -
it should be smart enough to shift the user traffic to MS that is up.

> * I would suggest that after we block traffic coming from
8080/8443/8250(we
will need to block this as well right?), we can log the execution of tasks.
I mean, something saying, there are XXX tasks (enumerate tasks) still being
executed, we will wait for them to finish before shutting down

8250 - is a bit too aggressive in my opinion andwe dont want to do that. If
you block 8250 and you have a long running tasks - you are waiting on to
complete - then it may fail - because you block agent communication on 8250.

Thanks
ilya


On Wed, Apr 4, 2018 at 1:36 PM, Rafael Weingärtner <
rafaelweingartner@xxxxxxxxx> wrote:

> Big +1 for this feature; I only have a few doubts.
>
> * Regarding the tasks/jobs that management servers (MSs) execute; are these
> tasks originate from requests that come to the MS, or is it possible that
> requests received by one management server to be executed by other? I mean,
> if I execute a request against MS1, will this request always be
> executed/threated by MS1, or is it possible that this request is executed
> by another MS (e.g. MS2)?
>
> * I would suggest that after we block traffic coming from 8080/8443/8250(we
> will need to block this as well right?), we can log the execution of tasks.
> I mean, something saying, there are XXX tasks (enumerate tasks) still being
> executed, we will wait for them to finish before shutting down.
>
> * The timeout (60 minutes suggested) could be global settings that we can
> load before executing the graceful-shutdown.
>
> On Wed, Apr 4, 2018 at 5:15 PM, ilya musayev <ilya.mailing.lists@xxxxxxxxx
> >
> wrote:
>
> > Use case:
> > In any environment - time to time - administrator needs to perform a
> > maintenance. Current stop sequence of cloudstack management server will
> > ignore the fact that there may be long running async jobs - and terminate
> > the process. This in turn can create a poor user experience and
> occasional
> > inconsistency  in cloudstack db.
> >
> > This is especially painful in large environments where the user has
> > thousands of nodes and there is a continuous patching that happens around
> > the clock - that requires migration of workload from one node to another.
> >
> > With that said - i've created a script that monitors the async job queue
> > for given MS and waits for it complete all jobs. More details are posted
> > below.
> >
> > I'd like to introduce "graceful-shutdown" into the systemctl/service of
> > cloudstack-management service.
> >
> > The details of how it will work is below:
> >
> > Workflow for graceful shutdown:
> >   Using iptables/firewalld - block any connection attempts on 8080/8443
> (we
> > can identify the ports dynamically)
> >   Identify the MSID for the node, using the proper msid - query async_job
> > table for
> > 1) any jobs that are still running (or job_status=“0”)
> > 2) job_dispatcher not like “pseudoJobDispatcher"
> > 3) job_init_msid=$my_ms_id
> >
> > Monitor this async_job table for 60 minutes - until all async jobs for
> MSID
> > are done, then proceed with shutdown
> >     If failed for any reason or terminated, catch the exit via trap
> command
> > and unblock the 8080/8443
> >
> > Comments are welcome
> >
> > Regards,
> > ilya
> >
>
>
>
> --
> Rafael Weingärtner
>