Add Default values and Validations in Build related CRDs

[zhangtbj]

We should also have a better way to set the Default values and related validations in our CRDs side so that we can improve our CRD definition directly.

• After Kube 1.17, we can set the default value in CRDs, then we set some values for timeout (10mins) or revision (master), if the end-user doesn't set it: https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#validation

• We can also try to set some validations to check if the git url or image url is valid.

              properties:
                cronSpec:
                  type: string
                  pattern: '^(\d+|\*)(/\d+)?(\s+(\d+|\*)(/\d+)?){4}$'
                  default: "5 0 * * *"
                image:
                  type: string
                replicas:
                  type: integer
                  minimum: 1
                  maximum: 10
                  default: 1

• Then we need to see if the operator-sdk can set this kind of data and auto-generate in CRD YAML directly.

So we can follow the kubebuilder:validation style to allow operator-sdk helps us to add validation on CRDs automatically:
https://book.kubebuilder.io/reference/markers/crd-validation.html

Then once the CRD is generated, validation will be added directly by:

• https://book-v1.book.kubebuilder.io/beyond_basics/generating_crd.html
• https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#validation

For example, we can add:

• // +kubebuilder:validation:MinLength=1 for ALL required parameters to make sure the they are not empty, like Output.ImageURL, StrategyRef.Name, Source.URL, etc...
• // +kubebuilder:validation:Pattern:=((git|ssh|http(s)?)|(git@[\w\.]+))(:(//)?)([\w\.@\:/\-~]+)(\.git)(/)? for Source.URL to make sure the Git URL is a correct format
• Maybe Output.ImageURL also have a kind of format to check?
• BuildRef check in BuildRun
• Timeout format check
• etc ...

Then we can run operator-sdk generate crds, the related validations will be added in the CRD validation.openAPIV3Schema automatically, like:

                image:
                  description: ImageURL is the URL where the image will be pushed
                    to.
                  minLength: 1
                  type: string