I heard that the latest Kubernetes version has introduced live migration for pods between nodes. I brought it up during our daily stand-up meeting and my manager asked for some documentation to back this up, but I couldn't find any information. Can anyone help me out with this?
4 Answers
It sounds like you're referring to the checkpoint API, but it's a bit misleading because it doesn't really do what you might expect it to. You can find more details in the documentation about it here: https://kubernetes.io/docs/reference/node/kubelet-checkpoint-api/. For live migration issues, you might want to check out related discussions on GitHub, for example: https://github.com/kubernetes/kubernetes/issues/135178.
Also, take a look at https://github.com/ctrox/zeropod. It could have some useful insights regarding pod migration.
From what I know, the only true live migration is with VMs. If your Kubernetes pod is running inside a VM, you can migrate the entire VM along with its pods. However, I believe that's not what you're looking for. Live migration of a pod itself doesn't really add much value, since Kubernetes has mechanisms to move pods effectively. For instance, if you need to cordon a node, you can stop a pod and Kubernetes will automatically start a new one on a different node, making use of load balancers to keep things running seamlessly.
Right, and in cases like databases that require a lot of time to set up their caches, live migrating a pod can save a significant amount of initialization time.
You might want to check out this article: https://cast.ai/solutions/container-live-migration/. Just a heads up, it's a paid solution from CastAI.
I mostly agree, but there are some specific scenarios where live migration is beneficial, such as complex, long-running batch jobs or AI training workloads. These can be tricky to restart without effective checkpointing at the application level.