Use Operator SDK framework

[zroubalik]

Keda controller is rewritten to use operator-sdk framework. The controller logic was simplified removing informers, locks...

Usage changes

• adding Operator SDK tooling Use Operator SDK #54
• enable Keda to be deployed as namespaced/cluster-wide controller, ie. there can be deployed multiple Keda controllers, each serving specific namespace only

Major internal changes

• changes on ScaledObject are handled by Reconcile loop, it creates and manages lifecycle of the relevant HPA(in case of deploment) and then starting Scale Loop
• created dependent resources are properly deleted by Finalizer on ScaledObject
• operator is not holding any state in the code (previously sync.RWMutex in ScaleHandler, etc)
• External Metrics Names are stored in the ScaledObejct Status
• not using Clientset anymore, but using Controller Runtime Client API
• Metrics adapter was moved to the separate container, GetExternalMetricNames() and GetScaledObjectMetrics() are moved from ScaleHandler directly to the provider
• now using Structured logging provided by Operator SDK Logging,
• Debug log messages previously logged via log.Debug(msg) are now logged under Level 1, ie. log.V(1).Info(msg), this allow us to add more granularity in logging in the future (introduce Level 2/3/4 if needed)
• Permissions were a little bit restricted, previous were to wide (cluster-admin for keda-operator SA)

Deploying this version of Keda

This implementation can be deployed by running these commands, it is expecting existing keda namespace

git clone https://github.com/zroubalik/keda.git -b operator-sdk
cd keda
sed -i 's/kedacore/zroubalik/g' deploy/operator.yaml  
kubectl apply -f deploy/crds/keda.k8s.io_scaledobjects_crd.yaml
kubectl apply -f deploy/crds/keda.k8s.io_triggerauthentications_crd.yaml
kubectl apply -f deploy/

TODO

• set appropriate loging levels V(?) for log messages previously marked as Debug sections in the code (Debug -> V(1))
• tweak adapter logging
• test adapter (Kafka scaler working correctly)
• test namespaced vs cluster wide operator

[msftclas]

All CLA requirements met.

[zroubalik]

Into PR's description I've added instructions on how to deploy this code.

[zroubalik]

I've tweaked rest of the outstanding minor issues. I've tested this on OpenShift 4 using Kafka trigger, worked as expected. The code is ready for a Review and Merge.

Helm chart update might be needed after merging this PR

[zroubalik]

@tomkerkhove you might be interested to take a look on this PR

[tomkerkhove]

Thanks for the ping @zroubalik but I'll leave it up to @ahmelsayed as I'm not that knowledgeable on this level.

[jeffhollan]

I'll spend some time this week to test out this fork, @ahmelsayed plans to review sometime in the next week

[jeffhollan]

Validated that this works with my demos around Service Bus and Rabbit MQ. Thanks @zroubalik

[ahmelsayed]

I think this line is not needed, right? It fails for me on both images on a make build. Removing it from both resolves the issue.

[ahmelsayed]

Actually I think that folder is just missing the user_setup script.

[zroubalik]

Good catch, thanks. .gitignore was too strict and prevented pushing those files. There's so much files, so I haven't noticed that. I'll fix it in a few.

[zroubalik]

@ahmelsayed should be fixed now, PTAL

[ahmelsayed]

Thank you very much @zroubalik. The change looks good to me. instead of going over every file change here, I tested main scenarios and make sure I can read the new operator-sdk code.

make build has that one issue about the missing bin folder, but it's a very minor thing. I'll merge it once you add that folder (or I can also just merge it and send a PR with it since I already need to update some of the CI scripts)

[zroubalik]

@ahmelsayed @jeffhollan I have added one last minor change. The original cluster permissions were to wide (granting cluster-admin to the keda SA). I have restricted the permissions a little bit and have tested it and working for me. I might want to test it with your scenarios or at least one :)

[joskfg]

The go version is supposed to be "go ." this is producing that I'm not able to use this package as dependency for a controller.

[zroubalik]

@joskfg #718

[joskfg]

Thanks a lot!