caicloud / leader-election-example

This example demonstrates how to write high availability controller with GO.

Table of Contents generated with DocToc

• Leader Election Example
  • Running
  • Health Check

Leader Election Example

This example demonstrates how to use the leader election package.

Running

Run the following three commands in separate terminals.

# first terminal
go run main.go -kubeconfig=/path/to/kubeconfig -logtostderr=true -lease-lock-name=example -lease-lock-namespace=default -id=0 -port=8080

# second terminal
go run main.go -kubeconfig=/path/to/kubeconfig -logtostderr=true -lease-lock-name=example -lease-lock-namespace=default -id=1 -port=8081

# third terminal
go run main.go -kubeconfig=/path/to/kubeconfig -logtostderr=true -lease-lock-name=example -lease-lock-namespace=default -id=2 -port=8082

You can ignore the -kubeconfig flag if you are running these commands in the Kubernetes cluster.

Now kill the existing leader. You will see from the terminal outputs that one of the remaining two processes will be elected as the new leader.

Health Check

$ curl -i localhost:8080/healthz
HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
X-Content-Type-Options: nosniff
Date: Thu, 19 Sep 2019 10:44:39 GMT
Content-Length: 2

ok%

$ curl -i localhost:8080/healthz/leaderElection
HTTP/1.1 200 OK
Date: Thu, 19 Sep 2019 10:44:31 GMT
Content-Length: 2
Content-Type: text/plain; charset=utf-8

ok%