leaderelection 0.0.2

Kubernetes leader election

k8s-leader-election-py

Client-go has a very easy to use leader-election package for kubernetes controllers to utilize leader-election. The pyhton kubernetes-client doesn't have such a method, so this will have to do for now.

Usage

Your controller must have a pod and namespace environment variable defined:

env:
- name: POD
  valueFrom:
    fieldRef:
      fieldPath: metadata.name
- name: NAMESPACE
  valueFrom:
    fieldRef:
      fieldPath: metadata.namespace

Sample code:

from threading import Thread
from leaderelection import Elect

# Init leader election class. Configmap is the name of the configmap to create to store leader election information
leaderelection = Elect(configmap='sample-controller-leader-election')
# Run leader election in new thread
th = Thread(target=leaderelection.run)
th.setDaemon(True)
th.start()
#start main controller loop
while True:
    # Check if pod is the leader. If so continue on with controller logic.
    leader = leaderelection.check_leader()
    if leader:
        logger.info("I am the leader!!")
    else:
        logger.info("I am NOT the leader")

An example of this can be found in the sample-controller directory.