MongoDB Scalers open many open connections about keda

[JorTurFer]

Hello @MichaelMayer-askui ,
Thanks for reporting! Do you see any error in keda-operator logs? Could you confirm the KEDA version you are using?

[MichaelMayer-askui]

Hello @JorTurFer ,
The versions i can confirm, all keda components on version 2.13.1, see screeshoot.

The only error message from keda-operator which i receive is the following:

mongodb_scaler	failed to query DATABASE in COLLECTION_NAME, because of server selection error: context deadline exceeded, current topology: { Type: ReplicaSetNoPrimary, Servers: [{ Addr: ATLAS_URL.mongodb.net:27017, Type: RSSecondary, Tag sets: diskState=READY,availabilityZone=AZ,nodeType=ELECTABLE,provider=AWS,region=AZ,workloadType=OPERATIONAL, Average RTT: 1230992348 }, { Addr: ATLAS_URL.mongodb.net:27017, Type: RSSecondary, Tag sets: provider=AWS,diskState=READY,region=AZ,workloadType=OPERATIONAL,availabilityZone=AZ,nodeType=ELECTABLE, Average RTT: 3196250 }, { Addr: ATLAS_URL.mongodb.net:27017, Type: Unknown, Last error: dial tcp IP:27017: connect: connection refused }, ] }	{"type": "ScaledJob", "namespace": "NAMESPACE_NAME", "name": "SCALED_JOB_NAME", "error": "server selection error: context deadline exceeded, current topology: { Type: ReplicaSetNoPrimary, Servers: [{ Addr: ATLAS_URL.mongodb.net:27017, Type: RSSecondary, Tag sets: diskState=READY,availabilityZone=AZ,nodeType=ELECTABLE,provider=AWS,region=AZ,workloadType=OPERATIONAL, Average RTT: 1230992348 }, { Addr: ATLAS_URL.mongodb.net:27017, Type: RSSecondary, Tag sets: provider=AWS,diskState=READY,region=AZ,workloadType=OPERATIONAL,availabilityZone=AZ,nodeType=ELECTABLE, Average RTT: 3196250 }, { Addr: ATLAS_URL.mongodb.net:27017, Type: Unknown, Last error: dial tcp IP:27017: connect: connection refused }, ] }"}
github.com/kedacore/keda/v2/pkg/scalers.(*mongoDBScaler).getQueryResult
	/workspace/pkg/scalers/mongo_scaler.go:231
github.com/kedacore/keda/v2/pkg/scalers.(*mongoDBScaler).GetMetricsAndActivity
	/workspace/pkg/scalers/mongo_scaler.go:240
github.com/kedacore/keda/v2/pkg/scaling/cache.(*ScalersCache).GetMetricsAndActivityForScaler
	/workspace/pkg/scaling/cache/scalers_cache.go:130
github.com/kedacore/keda/v2/pkg/scaling.(*scaleHandler).getScaledJobMetrics
	/workspace/pkg/scaling/scale_handler.go:830
github.com/kedacore/keda/v2/pkg/scaling.(*scaleHandler).isScaledJobActive
	/workspace/pkg/scaling/scale_handler.go:879
github.com/kedacore/keda/v2/pkg/scaling.(*scaleHandler).checkScalers
	/workspace/pkg/scaling/scale_handler.go:262
github.com/kedacore/keda/v2/pkg/scaling.(*scaleHandler).startScaleLoop
	/workspace/pkg/scaling/scale_handler.go:182

This message occurs after the high amount of connection is open and the database refused more.

[JorTurFer]

Is your connection using mongo+svr scheme? v2.13.1 doesn't support it. I mean, if you are using Mongo Atlas based on mongo+srv scheme, it could be the problem itself. The support for the scheme was added 3 weeks ago: #5566

Maybe you could try the main tag setting the scheme as it's explained in next version docs: https://keda.sh/docs/2.14/scalers/mongodb/

[MichaelMayer-askui]

Yes the connection string is in mongo+svr scheme. I will test, if the problem will be resolved by adjusting the connection string.

Now I am surprised that it works. I used this config for now ~1 year without any issues. The problems occurred right after the update to v2.13 from v2.12.
Should this not produce an error regarding wrong configuration?

[JorTurFer]

Should this not produce an error regarding wrong configuration?

It could be, I don't remind related changes but they definitively could be there, for example the mongo pkg has been updated too

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.