[crd-gen] Support openAPIV3Schema fields: minimum, maximum, pattern, nullable

[leoandrea7]

Is your enhancement related to a problem? Please describe

(duplicate of #2959)

At the moment there is no way to auto generate a crd (with crd-gen tool) that contains properties with validation fields like minimum, maximum, pattern, nullable.

CRD example:

...

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: tenants.example.com
spec:
  group: example.com
  names:
    kind: Tenant
    plural: tenants
    singular: tenant
  scope: Namespaced
  versions:
  - name: v1
    schema:
      openAPIV3Schema:
        properties:
          spec:
            properties:
              kafka:
                type: object
                properties:
                  port:
                    type: integer
                    minimum: 0
                    maximum: 65535
                    nullable: false
                  hostname:
                    type: string
                    pattern: '^([A-Za-z0-9-]{1,63}\.)+[[A-Za-z0-9-]{1,63}$'
                    nullable: false
                nullable: false
...

Describe the solution you'd like

I'd like to use javax annotation (like @min @max @pattern) on a java model fields.

private String protocol;

@Pattern(regexp = "\\^\\(\\[A-Za-z0-9-]\\{1,63}\\\\\\.\\)\\+\\[\\[A-Za-z0-9-]\\{1,63}\\$")
private String hostname;

@Min(0)
@Max(65535)
private Integer port;

Currently @NotNull annotation generate the filed "required" on crd, but for "nullable" validation maybe we need of a new specific annotation.

Describe alternatives you've considered

No response

Additional context

version: 5.12.2

[OneCricketeer]

Is the pattern in your model example correct? The ^ and parentheses should not be literals, for example. The only change from the yaml should be escaping the one \\.

[leoandrea7]

@OneCricketeer Yes you are right but is not important the regex value now...The problem here is that crd-gen not have the featuare to read @Pattern @Max @Min and to generate corresponding fields(pattern, maximum and minimum) into the generated crd yaml file.
I think that the logic to handle this annotations should be into AbstractJsonSchema as for the other already supported annotations.

[sunix]

@andreaTP could you have a look at this issue?

[andreaTP]

I'm about to go on vacation, but if no one picks it up earlier I might eventually take a look at this.

[manusa]

Relates to:

• Improve Custom Resources handling #2611 (comment)
• crd-generator and annotations #2959 (duplicate)

[metacosm]

I have to admit that I'm a little lost on the subtleties of required and nullable… if something is not marked as required, shouldn't it be nullable by default? Conversely, if something is marked required, it cannot be nullable so I'm not sure why we need to support both… especially because then there might be conflicts i.e. what is the generator supposed to do (apart from throwing an error, I guess) if a property is both marked as nullable and required?

[andreaTP]

Closed in #4348