Python script to get all members of a given fleet clustergroup

getclustergroupmembers.py

import json
import subprocess
import sys

# fleet clustergroup membership is dynamic based on the rules in the clustergroup definition
# Those rules are either a matchExpressions selector, a matchLabels selector or a combination of both.
# This script gets the clustergroup name as parameter and get's the rule definition in json format.
# Those rules are then formated to be used in kubectl command that finds all the fleet clustergroup
# members that match those rules and show the in the standard out put.

def run_kubectl_command(cluster_group_name):
    cmd = ['kubectl', 'get', 'clustergroup.fleet.cattle.io', cluster_group_name, '--namespace', 'fleet-default', '-o', 'json']
    result = subprocess.run(cmd, capture_output=True, text=True)
    if result.returncode != 0:
        print("Error running kubectl command:", result.stderr)
        sys.exit(1)
    return json.loads(result.stdout)

def extract_match_labels(selector_json):
    return ','.join([f'{k}={v}' for k, v in selector_json.get('matchLabels', {}).items()])

def extract_match_expressions(selector_json):
    expressions = []
    for expr in selector_json.get('matchExpressions', []):
        key = expr['key']
        operator = expr['operator']
        values = expr['values']
        if operator == 'In':
            expressions.append(f'{key} in ({",".join(values)})')
        elif operator == 'NotIn':
            expressions.append(f'{key} notin ({",".join(values)})')
        elif operator in ['<', '>']:
            expressions.append(f'{key} {operator} {values[0]}')
    return ','.join(expressions)

def main(cluster_group_name):
    selector_json = run_kubectl_command(cluster_group_name)['spec']['selector']
    match_labels = extract_match_labels(selector_json)
    match_expressions = extract_match_expressions(selector_json)

    selector = ','.join(filter(None, [match_labels, match_expressions]))
    if selector:
        kubectl_cmd = f'kubectl get clusters.fleet.cattle.io --namespace fleet-default -o=custom-columns=MEMBERS:.metadata.name -l "{selector}"'
        #print("Running command:", kubectl_cmd)
        subprocess.run(kubectl_cmd, shell=True)
    else:
        print("No valid selector found.")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python script.py <ClusterGroup-Name>")
        sys.exit(1)
    main(sys.argv[1])