Lease API | Kubernetes

In this video I discuss the use of leases in kubernetes and how they are used for monitoring node health and leader election in HA applications.

[@itdots543]

thank you! The best tutorial I've seen so far.

[@jmmtechnology4539]

Glad you found it useful!

[@imbordred]

Can you do a series where you troubleshoot or a questions challenge? Thanks for a great seres :)!

[@anveshreddyoffofficial6581]

What's the reason for a lease to be used by node? For kube API to know the status of the node, can't kubelet of that node just send the requests directly to the API server instead of updating the lease? I can't see how the lease is helpful for nodes. Although I agree with you for distributed case we need leases.

[@jmmtechnology4539]

Good question, my understanding is that the main reason for using the lease API is for performance, in particular for larger clusters. You can find a detailed explanation on why leases are now used for node heartbeats here: github.com/kubernetes/enhancements/tree/master/keps/sig-node/589-efficient-node-heartbeats

[@anveshreddyoffofficial6581]

@@jmmtechnology4539 Thanks for the reply :). Will check that out!!

[@anveshreddyoffofficial6581]

@@jmmtechnology4539 I did check it out and as you said it's because of the performance. They used to do this earlier but because of etcd going out of storage easily due to these update frequency being just 10s and it has to store this info. They moved away from it by introducing a lease for this. Great read!. Thanks a lot for the resource. Would love if you make more videos on these concepts explaining things internally, why they did what they did. Thanks a lot.

[@gdevelek]

The important thing is to show how leases can be used to coordinate a two-replica app to have one active and one passive replica.