PetSet Scaling and Volume Management in Kubernetes

default test-petset-0 1/1 Running 0 7s default test-petset-1 1/1 Running 0 3s ``` Here is how the PetSet test-petset instantiated earlier looks like: ``` [root@tlx241 /]# kubectl describe petset test-petset Name: test-petset Namespace: default Image(s): [gcr.io/google\_containers/nginx-slim:0.8](http://gcr.io/google_containers/nginx-slim:0.8) Selector: app=nginx Labels: app=nginx Replicas: 2 current / 2 desired Annotations: \<none\> CreationTimestamp: Sun, 14 Aug 2016 19:46:30 -0700 Pods Status: 2 Running / 0 Waiting / 0 Succeeded / 0 Failed No volumes. No events. ``` Once a PetSet is instantiated, such as test-petset below, upon increasing the number of replicas (i.e. the number of pods started with that PetSet), more pods get instantiated and more PersistentVolume Claims get bound to new pods: ``` [root@tlx241 /]# kubectl patch petset test-petset -p'{"spec":{"replicas":"3"}}' "test-petset” patched [root@tlx241 /]# kubectl describe petset test-petset Name: test-petset Namespace: default Image(s): [gcr.io/google\_containers/nginx-slim:0.8](http://gcr.io/google_containers/nginx-slim:0.8) Selector: app=nginx Labels: app=nginx Replicas: 3 current / 3 desired Annotations: \<none\> CreationTimestamp: Sun, 14 Aug 2016 19:46:30 -0700 Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed No volumes. No events. [root@tlx241 /]# kubectl get pods NAME READY STATUS RESTARTS AGE test-petset-0 1/1 Running 0 29m test-petset-1 1/1 Running 0 28m test-petset-2 1/1 Running 0 9s ``` Now the PetSet is running 3 pods after patch application. When the above PetSet definition is patched to have one more replica, it introduces one more pod in the system. This in turn results in one more volume getting provisioned on the Datera Data Fabric. So volumes get dynamically provisioned and attached to a pod upon the PetSet scaling up. To support the notion of durability and consistency, if a pod moves from one minion to another, volumes do get attached (mounted) to the new minion node and detached (unmounted) from the old minion to maintain persistent access to the data. **Conclusion** This demonstrates Kubernetes with Pet Sets orchestrating stateful and stateless workloads. While the Kubernetes community is working on expanding the FlexVolume framework’s capabilities, we are excited that this solution makes it possible for Kubernetes to be run more widely in the datacenters. Join and contribute: Kubernetes [Storage SIG](https://groups.google.com/forum/#!forum/kubernetes-sig-storage). - [Download Kubernetes](http://get.k8s.io/) - Get involved with the Kubernetes project on [GitHub](https://github.com/kubernetes/kubernetes) - Post questions (or answer questions) on [Stack Overflow](http://stackoverflow.com/questions/tagged/kubernetes) - Connect with the community on the [k8s Slack](http://slack.k8s.io/) - Follow us on Twitter [@Kubernetesio](https://twitter.com/kubernetesio) for latest updates

This section illustrates how scaling a PetSet in Kubernetes dynamically provisions and attaches volumes to newly created pods. Patching the PetSet to increase the number of replicas leads to the instantiation of additional pods and the provisioning of corresponding volumes. The system ensures data durability and consistency by attaching volumes to new minion nodes when pods move, while detaching them from the old nodes. The conclusion emphasizes Kubernetes' orchestration capabilities for both stateful and stateless workloads and encourages community involvement. It also provides links for downloading Kubernetes, contributing on GitHub, asking questions on Stack Overflow, and connecting on Slack and Twitter.