WIP: feat: Add schema validation to CRDs

[tumido]

I've tried to implement OpenAPI spec for CRDs using controller-gen, but it seems that the field validation is not fully/properly implemented. Not sure how else this problem can be approached. Feel free to dismiss this PR if you don't like this approach...

• Added new dependency (controller-gen)
• Added hack/update-crd.sh script

I'm getting these errors:

Sensor:

home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/common/s3.go:32:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:209:2: encountered struct field "Duration" without JSON tag in type "Backoff"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:214:2: encountered struct field "Factor" without JSON tag in type "Backoff"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:218:2: encountered struct field "Jitter" without JSON tag in type "Backoff"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:224:2: encountered struct field "Steps" without JSON tag in type "Backoff"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:229:2: encountered struct field "Cap" without JSON tag in type "Backoff"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:256:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:211:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:131:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:315:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:318:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:789:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:333:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:346:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:357:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:369:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:417:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:422:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:493:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:496:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:436:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:455:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:470:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:473:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:505:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:539:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:544:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:269:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:631:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:134:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:198:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1/types.go:145:2: ListType must be either "map", "set" or "atomic"
Error: not all generators ran successfully
run `controller-gen crd:crdVersions=v1 paths=github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1 output:stdout -w` to see all available markers, or `controller-gen crd:crdVersions=v1 paths=github.com/argoproj/argo-events/pkg/apis/sensor/v1alpha1 output:stdout -h` for usage
exit status 1

Gateway:

/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/gateway/v1alpha1/types.go:83:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/gateway/v1alpha1/types.go:87:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/gateway/v1alpha1/types.go:72:2: must apply listType to an array
Error: not all generators ran successfully
run `controller-gen crd:crdVersions=v1 paths=github.com/argoproj/argo-events/pkg/apis/gateway/v1alpha1 output:stdout -w` to see all available markers, or `controller-gen crd:crdVersions=v1 paths=github.com/argoproj/argo-events/pkg/apis/gateway/v1alpha1 output:stdout -h` for usage
exit status 1

EventSource:

/home/tcoufal/.go/src/github.com/argoproj/argo-events/common/retry.go:29:11: unsupported type "float64"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/common/retry.go:30:11: unsupported type "float64"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/common/s3.go:32:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1/types.go:110:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1/types.go:342:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1/types.go:408:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1/types.go:456:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1/types.go:503:2: ListType must be either "map", "set" or "atomic"
/home/tcoufal/.go/src/github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1/types.go:552:2: ListType must be either "map", "set" or "atomic"
Error: not all generators ran successfully
run `controller-gen crd:crdVersions=v1 paths=github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1 output:stdout -w` to see all available markers, or `controller-gen crd:crdVersions=v1 paths=github.com/argoproj/argo-events/pkg/apis/eventsources/v1alpha1 output:stdout -h` for usage
exit status 1

Help welcomed.

[yoichiwo7]

@tumido
Hi.
You'll need to fix the CRD type files but it may not be easy. (Especially when you need to change the existing CRD related field types)

• The golang markers such as // +listType=value are invalid. You can only specify certain values for listType as error message indicates.
  https://kubernetes.io/docs/reference/using-api/api-concepts/#merge-strategy

• Sensor type is using wait.Backoff struct that has fields without json tag. controller-gen can't generate OpenAPI definition from the field without json tag. Even if you use the Backoff struct with json tag included in the sensor type code, you have to fix float64 problem mentioned in next bullet point.
  

  argo-events/pkg/apis/sensor/v1alpha1/types.go

  Line 634 in cb1358d

  // Backoff for an operation

• controller-gen doesn't support float type. See the following issue for details.
  Support floats? kubernetes-sigs/controller-tools#245

[VaibhavPage]

Closing PR as we won't be adding any validations to CRD anytime soon.