Interesting Kubernetes Problem

When you choose to have more than 110 pods/node, kubelet can face many issues.

• Performance degradation.
• Competition for resources (CPU, Memory etc.)
• Application stability concerns.

And many more.

This is a follow up to this post here.

But today let's talk about - "PLEG issues."

PLEG stands for "Pod Lifecycle Event Generator".

It is responsible for tracking pod events and keeping the cluster stable. This will "report back to Kubelet" about the state of Pods.

With more Pods in cluster, PLEG can experiences more lifecycle events.

This can include (creation, deletion, restarts) that it needs to track.

With heavy load, time out issues can creep in. Mainly because it can't track everything due to overload. This can mark the node as "NotReady" in the cluster.

You will see errors like - "PLEG is not healthy."

Sometimes, these issues will come and go.

But they will reappear as you increase total number of Pods running on a node.

How do you fix them?

1. Increase nodes in cluster.

2. Distribute the Pods across all nodes.

Perfectionism kills progress. Focus on getting thing done ??

Also.

Sometimes PLEG issues can come in a fresh cluster.

And there can be variety of reasons for it.

Some of them include:

1. Hostname resolution issues in nodes.

2. CNI Plugin issues on cluster.

3. Firewall rules to allow CNI.

We can discuss more about this in future Newsletters. Knowing possibilities will keep you ready when things go wrong.

So, bookmark this page for future reference.

It can happily save you from some trouble ??

Hope it's useful.

Let me know what you think.

A repost helps.??

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