What is the regex for kubernetes label?

The regex pattern for kubernetes label is `^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$`. This pattern validates kubernetes label key with optional prefix (prefix/name).

How do I use this regex in Python?

In Python, use `import re; re.match(r'^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$/i`) or use `re.IGNORECASE` in Python.

Regex for Kubernetes Label

Q: How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

Regex Pattern

^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$

Kubernetes label key with optional prefix (prefix/name)

Quick Answer

The regex pattern for kubernetes label is `^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$`. Kubernetes label key with optional prefix (prefix/name). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
app.kubernetes.io/name	✓ Matches
example.com/version	✓ Matches
tier/frontend	✓ Matches
/no-prefix	✗ No match
-invalid/name	✗ No match
toolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolongtoolong/label	✗ No match

Code Examples

javascript

const regex = /^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$/;
const isValid = regex.test(value);

python

import re
pattern = r'^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$/', $value)) {
    echo "valid";
}

java

String pattern = "^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\\.)*[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\\/[a-zA-Z0-9](?:[-a-zA-Z0-9_.]{0,61}[a-zA-Z0-9])?$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

Related Regex Patterns

JavaScript Variable Name

Valid JavaScript variable/identifier name

Python Variable Name

Valid Python identifier name

CSS Class Name

Valid CSS class name (starts with letter, underscore, or hyphen)

CSS ID Selector

CSS ID selector starting with #

JSON Key

JSON object key (quoted string followed by colon)

Semantic Version (Strict)

Strict semantic versioning (MAJOR.MINOR.PATCH)