A python implementation of generating pod names from the metadata.generateName field for use in mutating webhook admission controllers

generate_name.py

import random


def generate_name(prefix):
    """
    Generates a name for a resource in the same way the Kubernetes API servers
    would (appending a suffix of up to 5 random alphanumeric characters).
    """
    # no vowels, so "bad words" can't be formed
    alphanums = 'bcdfghjklmnpqrstvwxz2456789'
    # Up to 5 random characters, don't exceed max name length
    random_len = min(5, 63 - len(prefix))
    generated_part = ''.join(random.choice(alphanums) for _ in range(random_len))
    return prefix + generated_part


def ensure_pod_name(pod):
    """
    Pods created by Deployments do not have a name set by the time they reach
    the admission controllers, instead they have the generateName field set,
    which contains the prefix for the pod name. This function materializes the
    name and should be called if the admission controller requires knowledge
    of the pod name.
    """
    metadata = pod['metadata']
    if metadata.get('name'):
        return
    prefix = metadata.get('generateName')
    if not prefix:
        raise ValueError('Pod does not have name nor generateName set')
    metadata['name'] = generate_name(prefix)