JavaScript / ECMAScript

Kubernetes Label (key=value) in JS

Validate Kubernetes label `key=value` pairs per the K8s naming spec.

Try it in the JS tester →

Pattern

regexJS
^([a-zA-Z0-9](?:[\w.\-]{0,61}[a-zA-Z0-9])?)=([a-zA-Z0-9](?:[\w.\-]{0,61}[a-zA-Z0-9])?)?$

JavaScript / ECMAScript code

jsJavaScript
const re = new RegExp("^([a-zA-Z0-9](?:[\\w.\\-]{0,61}[a-zA-Z0-9])?)=([a-zA-Z0-9](?:[\\w.\\-]{0,61}[a-zA-Z0-9])?)?$", "");
const input = "app=myapp";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

How the pattern works

Both key and value follow the same rule: 1–63 chars, must start AND end with alphanumeric, can contain underscores/dots/hyphens in the middle. The value group is optional (empty values are allowed). Anchored with ^ and $ for strict full-string matching.

Examples

Input

app=myapp

Matches

  • app=myapp

Input

version=v1.2.3

Matches

  • version=v1.2.3

Input

-bad=value

No match

—

Same pattern, other engines

Python (re)

Supported

See how this pattern looks (and behaves) in Python's stdlib `re` module.

Go (RE2)

Supported

See how this pattern looks (and behaves) in Go's `regexp` package (RE2 engine).

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