Object Names and IDs - Add section for qualified names

[juliusl]

I was having a really rough time trying to figure out where the rules were defined for the type property of a PodCondition. I know underscores are allowed but I didn't find a rule in this part of the docs that mention that _ is allowed.

Turns out this is the code that validates that property,

https://github.com/kubernetes/kubernetes/blob/abc056843c030ead11551e13171a4447701db24e/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L42

(via https://github.com/kubernetes/kubernetes/blob/abc056843c030ead11551e13171a4447701db24e/pkg/apis/core/validation/validation.go#L5390)

Which has a really nice explanation of what a qualified name is right above it,

const qnameCharFmt string = "[A-Za-z0-9]"
const qnameExtCharFmt string = "[-A-Za-z0-9_.]"
const qualifiedNameFmt string = "(" + qnameCharFmt + qnameExtCharFmt + "*)?" + qnameCharFmt
const qualifiedNameErrMsg string = "must consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character"
const qualifiedNameMaxLength int = 63

var qualifiedNameRegexp = regexp.MustCompile("^" + qualifiedNameFmt + "$")

It would be great if this information was included in this particular doc.

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[tamilselvan1102]

related page: https://kubernetes.io/docs/concepts/overview/working-with-objects/names/

[tamilselvan1102]

/language en

[tamilselvan1102]

/sig docs

[sftim]

I think we should document this, but it belongs elsewhere. https://kubernetes.io/docs/concepts/overview/working-with-objects/names/ is about the name and uid fields within object metadata only. This issue is about object status.

[juliusl]

@sftim is the "qualified name" used elsewhere? Or is it specific to object status type naming? If the latter I agree but if the former, it might be beneficial to stick it in this section.

[tengqm]

I cannot think of a better location for this concept.

[sftim]

I'd put the explanation in https://kubernetes.io/docs/reference/glossary/ and transclude (eg {{< glossary_definition prepend="Kubernetes also has a concept of a qualified name, which is" term_id="qualified-name" >}})) it into the Object Names and IDs page.