[v2] migrate to Operator SDK v1.0.0

[zroubalik]

Signed-off-by: Zbynek Roubalik zroubali@redhat.com

OMG, sorry for the huge PR, there wasn't an easy way how to split things.

Operator SDK is finally in 1.0.0 version, this brought change in the project layout and other stuff. Now it is internally using Kubebuilder for project scaffolding and kustomize to generate YAML manifests. See the migration guide for details:
https://sdk.operatorframework.io/docs/building-operators/golang/project_migration_guide/

What was changed

• The deploy directory was replaced with the config directory including a new layout of Kubernetes manifests files:
  • CRD manifests in deploy/crds/ are now in config/crd/bases
  • CR manifests in deploy/crds/ are now in config/samples
  • Controller manifest deploy/operator.yaml is now in config/manager/manager.yaml
  • RBAC manifests in deploy are now in config/rbac/
  • Metrics server manifests are now in config/metrics-server
• build/Dockerfile andbuild/Dockerfile.adapter are moved to the project root directory
  • Dockerfiles were changed to multi-stage and distroless, this should reduce image size
• pkg/apis and pkg/controllers are now in the root directory.
  • there were only minor changes in the api and controllers code
• cmd/manager/main.go is now in the root director
• cmd/adapter/main.go is now in adapter/main.go
• kustomize is used to manage Kubernetes resources needed to deploy your operator
  • manifests are generated with proper version/image tags as specified in Makefile
  • ScaledJob generation is fixed for now (Kustomize enables us to use patches: https://github.com/kedacore/keda/blob/950c5e16deb143a8201189ec7430f7350d0fa6bd/config/crd/patches/scaledjob_patch.yaml)
• Makefile was modifed a lot, eg. you can use make deploy to deploy KEDA, make run to run locally and other useful steps
• Release process was simplified (no need to manually change version etc.) everything should be part of GitHub Release Action now
• We produce one release yaml file that contains all resources (eg. keda-2.0.0.yaml) instead of .zip or tar.gz artifacts
• We could use envtest test framework to test our controllers. The current test file is just a stub: https://github.com/kedacore/keda/blob/950c5e16deb143a8201189ec7430f7350d0fa6bd/controllers/suite_test.go
  • issue created: Test ScaledObject and ScaledJob Controllers  #1008

Checklist

• Commits are signed with Developer Certificate of Origin (DCO)
• Changelog has been updated

Fixes #969

[ahmelsayed]

Looks great @zroubalik! Thanks for doing all that. I just had a couple of questions, but it looks good to me.