Is that management server load balancing feature using static configurations? I heard about it on the mailing list, but I did not follow the implementation.
I do not see many problems with agents reconnecting. We can implement in agents (not just KVM, but also system VMs) a logic that instead of using a static pool of management servers configured in a properties file, they dynamically request a list of available management servers via that list management servers API method. This would require us to configure agents with a load balancer URL that executes the balancing between multiple management servers. I am +1 to remove the need for that VIP, which executes the load balance for connecting agents to management servers. On Fri, Apr 20, 2018 at 4:41 PM, ilya musayev <ilya.mailing.li...@gmail.com> wrote: > Rafael and Community > > All is well and good and i think we are thinking along the similar lines - > the only issue that i see right now with any approach is KVM Agents (or > direct agents) and using LoadBalancer on 8250. > > Here is a scenario: > > You have 2 Management Server setup fronted with a VIP on 8250. > The LB Algorithm is either Round Robin or Least Connections used. > You initiate a maintenance mode operation on one of the MS servers (call it > MS1) - assume you have a long running migration job that needs 60 minutes > to complete. > We attempt to evacuate the agents by telling them to disconnect and > reconnect again > If we are using LB on 8250 with > 1) Least Connection used - then all agents will continuously try to connect > to a MS1 node that is attempting to go down for maintenance. Essentially > with this LB configuration this operation will never > 2) Round Robin - this will take a while - but eventually - you will get all > nodes connected to MS2 > > The current limitation is usage of external LB on 8250. For this operation > to work without issue - would mean agents must connect to MS server without > an LB. This is a recent feature we've developed with ShapeBlue - where we > maintain the list of CloudStack Management Servers in the agent.properties > file. > > Unless you can think of other solution - it appears we may have to forced > to bypass the 8250 VIP LB and use the new feature to maintain the list of > management servers within agent.properties. > > > I need to run now, let me know what your thoughts are. > > Regards > ilya > > > > On Tue, Apr 17, 2018 at 8:27 AM, Rafael Weingärtner < > rafaelweingart...@gmail.com> wrote: > > > Ilya and others, > > > > We have been discussing this idea of graceful/nicely shutdown. Our > feeling > > is that we (in CloudStack community) might have been trying to solve this > > problem with too much scripting. What if we developed a more integrated > > (native) solution? > > > > Let me explain our idea. > > > > ACS has a table called “mshost”, which is used to store management server > > information. During balancing and when jobs are dispatched to other > > management servers this table is consulted/queried. Therefore, we have > > been discussing the idea of creating a management API for management > > servers. We could have an API method that changes the state of > management > > servers to “prepare to maintenance” and then “maintenance” (as soon as > all > > of the task/jobs it is managing finish). The idea is that during > > rebalancing we would remove the hosts of servers that are not in “Up” > state > > (of course we would also ignore hosts in the aforementioned state to > > receive hosts to manage). Moreover, when we send/dispatch jobs to other > > management servers, we could ignore the ones that are not in “Up” state > > (which is something already done). > > > > By doing this, the nicely shutdown could be executed in a few steps. > > > > 1 – issue the maintenance method for the management server you desire > > 2 – wait until the MS goes into maintenance mode, while there are still > > running jobs it (the management server) will be maintained in prepare for > > maintenance > > 3 – execute the Linux shutdown command > > > > We would need other APIs methods to manage MSs then. An (i) API method to > > list MSs, and we could even create an (ii) API to remove old/de-activated > > management servers, which we currently do not have (forcing users to > apply > > changed directly in the database). > > > > Moreover, in this model, we would not kill hanging jobs; we would wait > > until they expire and ACS expunges them. Of course, it is possible to > > develop a forceful maintenance method as well. Then, when the “prepare > for > > maintenance” takes longer than a parameter, we could kill hanging jobs. > > > > All of this would allow the MS to be kept up and receiving requests until > > it can be safely shutdown. What do you guys about this approach? > > > > On Tue, Apr 10, 2018 at 6:52 PM, Yiping Zhang <yzh...@marketo.com> > wrote: > > > > > As a cloud admin, I would love to have this feature. > > > > > > It so happens that I just accidentally restarted my ACS management > server > > > while two instances are migrating to another Xen cluster (via storage > > > migration, not live migration). As results, both instances > > > ends up with corrupted data disk which can't be reattached or migrated. > > > > > > Any feature which prevents this from happening would be great. A low > > > hanging fruit is simply checking for > > > if there are any async jobs running, especially any kind of migration > > jobs > > > or other known long running type of > > > jobs and warn the operator so that he has a chance to abort server > > > shutdowns. > > > > > > Yiping > > > > > > On 4/5/18, 3:13 PM, "ilya musayev" <ilya.mailing.li...@gmail.com> > > wrote: > > > > > > Andrija > > > > > > This is a tough scenario. > > > > > > As an admin, they way i would have handled this situation, is to > > > advertise > > > the upcoming outage and then take away specific API commands from a > > > user a > > > day before - so he does not cause any long running async jobs. Once > > > maintenance completes - enable the API commands back to the user. > > > However - > > > i dont know who your user base is and if this would be an > acceptable > > > solution. > > > > > > Perhaps also investigate what can be done to speed up your long > > running > > > tasks... > > > > > > As a side node, we will be working on a feature that would allow > for > > a > > > graceful termination of the process/job, meaning if agent noticed a > > > disconnect or termination request - it will abort the command in > > > flight. We > > > can also consider restarting this tasks again or what not - but it > > > would > > > not be part of this enhancement. > > > > > > Regards > > > ilya > > > > > > On Thu, Apr 5, 2018 at 6:47 AM, Andrija Panic < > > andrija.pa...@gmail.com > > > > > > > wrote: > > > > > > > Hi Ilya, > > > > > > > > thanks for the feedback - but in "real world", you need to > > > "understand" > > > > that 60min is next to useless timeout for some jobs (if I > > understand > > > this > > > > specific parameter correctly ?? - job is really canceled, not > only > > > job > > > > monitoring is canceled ???) - > > > > > > > > My value for the "job.cancel.threshold.minutes" is 2880 minutes > (2 > > > days?) > > > > > > > > I can tell you when you have CEPH/NFS (CEPH even "worse" case, > > since > > > slower > > > > read durign qemu-img convert process...) of 500GB, then imagine > > > snapshot > > > > job will take many hours. Should I mention 1TB volumes (yes, we > had > > > > client's like that...) > > > > Than attaching 1TB volume, that was uploaded to ACS (lives > > > originally on > > > > Secondary Storage, and takes time to be copied over to NFS/CEPH) > > > will take > > > > up to few hours. > > > > Then migrating 1TB volume from NFS to CEPH, or CEPH to NFS, also > > > takes > > > > time...etc. > > > > > > > > I'm just giving you feedback as "user", admin of the cloud, zero > > DEV > > > skills > > > > here :) , just to make sure you make practical decisions (and I > > > admit I > > > > might be wrong with my stuff, but just giving you feedback from > our > > > public > > > > cloud setup) > > > > > > > > > > > > Cheers! > > > > > > > > > > > > > > > > > > > > On 5 April 2018 at 15:16, Tutkowski, Mike < > > mike.tutkow...@netapp.com > > > > > > > > wrote: > > > > > > > > > Wow, there’s been a lot of good details noted from several > people > > > on how > > > > > this process works today and how we’d like it to work in the > near > > > future. > > > > > > > > > > 1) Any chance this is already documented on the Wiki? > > > > > > > > > > 2) If not, any chance someone would be willing to do so (a flow > > > diagram > > > > > would be particularly useful). > > > > > > > > > > > On Apr 5, 2018, at 3:37 AM, Marc-Aurèle Brothier < > > > ma...@exoscale.ch> > > > > > wrote: > > > > > > > > > > > > Hi all, > > > > > > > > > > > > Good point ilya but as stated by Sergey there's more thing to > > > consider > > > > > > before being able to do a proper shutdown. I augmented my > > script > > > I gave > > > > > you > > > > > > originally and changed code in CS. What we're doing for our > > > environment > > > > > is > > > > > > as follow: > > > > > > > > > > > > 1. the MGMT looks for a change in the file /etc/lb-agent > which > > > contains > > > > > > keywords for HAproxy[2] (ready, maint) so that HA-proxy can > > > disable the > > > > > > mgmt on the keyword "maint" and the mgmt server stops a > couple > > of > > > > > > threads[1] to stop processing async jobs in the queue > > > > > > 2. Looks for the async jobs and wait until there is none to > > > ensure you > > > > > can > > > > > > send the reconnect commands (if jobs are running, a reconnect > > > will > > > > result > > > > > > in a failed job since the result will never reach the > > management > > > > server - > > > > > > the agent waits for the current job to be done before > > > reconnecting, and > > > > > > discard the result... rooms for improvement here!) > > > > > > 3. Issue a reconnectHost command to all the hosts connected > to > > > the mgmt > > > > > > server so that they reconnect to another one, otherwise the > > mgmt > > > must > > > > be > > > > > up > > > > > > since it is used to forward commands to agents. > > > > > > 4. when all agents are reconnected, we can shutdown the > > > management > > > > server > > > > > > and perform the maintenance. > > > > > > > > > > > > One issue remains for me, during the reconnect, the commands > > > that are > > > > > > processed at the same time should be kept in a queue until > the > > > agents > > > > > have > > > > > > finished any current jobs and have reconnected. Today the > > little > > > time > > > > > > window during which the reconnect happens can lead to failed > > > jobs due > > > > to > > > > > > the agent not being connected at the right moment. > > > > > > > > > > > > I could push a PR for the change to stop some processing > > threads > > > based > > > > on > > > > > > the content of a file. It's possible also to cancel the drain > > of > > > the > > > > > > management by simply changing the content of the file back to > > > "ready" > > > > > > again, instead of "maint" [2]. > > > > > > > > > > > > [1] AsyncJobMgr-Heartbeat, CapacityChecker, StatsCollector > > > > > > [2] HA proxy documentation on agent checker: > > > https://cbonte.github.io/ > > > > > > haproxy-dconv/1.6/configuration.html#5.2-agent-check > > > > > > > > > > > > Regarding your issue on the port blocking, I think it's fair > to > > > > consider > > > > > > that if you want to shutdown your server at some point, you > > have > > > to > > > > stop > > > > > > serving (some) requests. Here the only way it's to stop > serving > > > > > everything. > > > > > > If the API had a REST design, we could reject any > > POST/PUT/DELETE > > > > > > operations and allow GET ones. I don't know how hard it would > > be > > > today > > > > to > > > > > > only allow listBaseCmd operations to be more friendly with > the > > > users. > > > > > > > > > > > > Marco > > > > > > > > > > > > > > > > > > On Thu, Apr 5, 2018 at 2:22 AM, Sergey Levitskiy < > > > serg...@hotmail.com> > > > > > > wrote: > > > > > > > > > > > >> Now without spellchecking :) > > > > > >> > > > > > >> This is not simple e.g. for VMware. Each management server > > also > > > acts > > > > as > > > > > an > > > > > >> agent proxy so tasks against a particular ESX host will be > > > always > > > > > >> forwarded. That right answer will be to support a native > > > “maintenance > > > > > mode” > > > > > >> for management server. When entered to such mode the > > management > > > server > > > > > >> should release all agents including SSVM, block/redirect API > > > calls and > > > > > >> login request and finish all async job it originated. > > > > > >> > > > > > >> > > > > > >> > > > > > >> On Apr 4, 2018, at 5:15 PM, Sergey Levitskiy < > > > serg...@hotmail.com > > > > > <mailto: > > > > > >> serg...@hotmail.com>> wrote: > > > > > >> > > > > > >> This is not simple e.g. for VMware. Each management server > > also > > > acts > > > > as > > > > > an > > > > > >> agent proxy so tasks against a particular ESX host will be > > > always > > > > > >> forwarded. That right answer will be to a native support for > > > > > “maintenance > > > > > >> mode” for management server. When entered to such mode the > > > management > > > > > >> server should release all agents including save, > > block/redirect > > > API > > > > > calls > > > > > >> and login request and finish all a sync job it originated. > > > > > >> > > > > > >> Sent from my iPhone > > > > > >> > > > > > >> On Apr 4, 2018, at 3:31 PM, Rafael Weingärtner < > > > > > >> rafaelweingart...@gmail.com<mailto:rafaelweingartner@ > > gmail.com > > > >> > > > > wrote: > > > > > >> > > > > > >> Ilya, still regarding the management server that is being > shut > > > down > > > > > issue; > > > > > >> if other MSs/or maybe system VMs (I am not sure to know if > > they > > > are > > > > > able to > > > > > >> do such tasks) can direct/redirect/send new jobs to this > > > management > > > > > server > > > > > >> (the one being shut down), the process might never end > because > > > new > > > > tasks > > > > > >> are always being created for the management server that we > > want > > > to > > > > shut > > > > > >> down. Is this scenario possible? > > > > > >> > > > > > >> That is why I mentioned blocking the port 8250 for the > > > > > “graceful-shutdown”. > > > > > >> > > > > > >> If this scenario is not possible, then everything s fine. > > > > > >> > > > > > >> > > > > > >> On Wed, Apr 4, 2018 at 7:14 PM, ilya musayev < > > > > > ilya.mailing.li...@gmail.com > > > > > >> <mailto:ilya.mailing.li...@gmail.com>> > > > > > >> wrote: > > > > > >> > > > > > >> I'm thinking of using a configuration from > > > > > "job.cancel.threshold.minutes" - > > > > > >> it will be the longest > > > > > >> > > > > > >> "category": "Advanced", > > > > > >> > > > > > >> "description": "Time (in minutes) for async-jobs to be > > > forcely > > > > > >> cancelled if it has been in process for long", > > > > > >> > > > > > >> "name": "job.cancel.threshold.minutes", > > > > > >> > > > > > >> "value": "60" > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> On Wed, Apr 4, 2018 at 1:36 PM, Rafael Weingärtner < > > > > > >> rafaelweingart...@gmail.com<mailto:rafaelweingartner@ > > gmail.com > > > >> > > > > 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.li...@gmail.com<mailto:ilya.mailing.lists@ > > > gmail.com> > > > > > >> > > > > > >> 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 > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> -- > > > > > >> Rafael Weingärtner > > > > > >> > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > Andrija Panić > > > > > > > > > > > > > > > > > > > -- > > Rafael Weingärtner > > > -- Rafael Weingärtner
