feat: add naming regex check on validating webhook

[anencore94]

What this PR does / why we need it:

When invalid-named experiment CREATE API was requested, such experiment status was shown as CREATED, but in fact it was not created.
Therefore, naming convention should be checked in validating webhook

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):

Fixes #1538

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

NONE

[aws-kf-ci-bot]

Hi @anencore94. Thanks for your PR.

I'm waiting for a kubeflow member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[johnugeorge]

/ok-to-test

[andreyvelich]

Thank you so much for your contribution @anencore94!
I left few comments.

[andreyvelich]

Should we follow the regex syntax from the controller-runtime suggestion ?

Suggested change

	namingConvention, _ := regexp.Compile("^[a-z]([-a-z0-9]*[a-z0-9])$")
	namingConvention, _ := regexp.Compile("[a-z]([-a-z0-9]*[a-z0-9])?")

[anencore94]

@andreyvelich
I'm not an expert with golang, I'm a bit confused with this:

package main

import (
	"fmt"
	"regexp"
)

func main() {
	namingConvention, _ := regexp.Compile("[a-z]([-a-z0-9]*[a-z0-9])?")
	fmt.Println(namingConvention.MatchString("test")) // true
	fmt.Println(namingConvention.MatchString("test-1234")) // true
	fmt.Println(namingConvention.MatchString("1234-1234")) // false
	fmt.Println(namingConvention.MatchString("1234-test")) // true!! this is what i didn't expected
	
	nc2, _ := regexp.Compile("^[a-z]([-a-z0-9]*[a-z0-9])?") // '^' was added
	fmt.Println(nc2.MatchString("test")) // true
	fmt.Println(nc2.MatchString("test-1234")) // true
	fmt.Println(nc2.MatchString("1234-1234")) // false
	fmt.Println(nc2.MatchString("1234-test")) // false!!, so I followed this regexp pattern.

}

That's why I used the pattern "^[a-z]([-a-z0-9]*[a-z0-9])?", not "[a-z]([-a-z0-9]*[a-z0-9])?"

[andreyvelich]

@anencore94 Thank you for investigating this, you are right.
As I can see, kubebuilder also adds ^ and $ to the regex: https://github.com/kubernetes-sigs/kubebuilder/blob/master/pkg/internal/validation/dns.go#L45.

[andreyvelich]

@anencore94 do you want to keep your first regex: ^[a-z]([-a-z0-9]*[a-z0-9])$ or with ? at the end ?

[anencore94]

I think my first regex was wrong since this case:

package main

import (
	"fmt"
	"regexp"
)

func main() {
	nc1, _ := regexp.Compile("^[a-z]([-a-z0-9]*[a-z0-9])?")
	fmt.Println(nc1.MatchString("test")) // true
	fmt.Println(nc1.MatchString("test-1234")) // true
	fmt.Println(nc1.MatchString("1234-1234")) // false
	fmt.Println(nc1.MatchString("1234-test")) // false
	fmt.Println(nc1.MatchString("t")) // true, That's what we expected
		
	fmt.Println("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
	
	nc2, _ := regexp.Compile("^[a-z]([-a-z0-9]*[a-z0-9])$")
	fmt.Println(nc2.MatchString("test")) // true
	fmt.Println(nc2.MatchString("test-1234")) // true
	fmt.Println(nc2.MatchString("1234-1234")) // false
	fmt.Println(nc2.MatchString("1234-test")) // false
	fmt.Println(nc2.MatchString("t")) // false!! this is what we didn't expected

	fmt.Println("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
	
	nc3, _ := regexp.Compile("^[a-z]([-a-z0-9]*[a-z0-9])?$")
	fmt.Println(nc3.MatchString("test")) // true
	fmt.Println(nc3.MatchString("test-1234")) // true
	fmt.Println(nc3.MatchString("1234-1234")) // false
	fmt.Println(nc3.MatchString("1234-test")) // false
	fmt.Println(nc3.MatchString("t")) // true, That's what we expected
}

I'm not sure what to use between nc and nc3.

But I guess we should use nc3 : ^[a-z]([-a-z0-9]*[a-z0-9])?$, since you mentioned, It seems golang always needs ^ and $.

[andreyvelich]

Thank you for the updates @anencore94!
/lgtm
/cc @johnugeorge

[johnugeorge]

/approve

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: anencore94, johnugeorge

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [johnugeorge]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment