---
title: " Stateful Applications in Containers!? Kubernetes 1.3 Says “Yes!” "
date: 2016-07-13
slug: stateful-applications-in-containers-kubernetes
url: /blog/2016/07/stateful-applications-in-containers-kubernetes
author: >
  [Mark Balch](https://twitter.com/markbalch) (Diamanti)
---

Congratulations to the Kubernetes community on another [value-packed release](https://kubernetes.io/blog/2016/07/kubernetes-1-3-bridging-cloud-native-and-enterprise-workloads/). A focus on stateful applications and federated clusters are two reasons why I’m so excited about 1.3. Kubernetes support for stateful apps such as Cassandra, Kafka, and MongoDB is critical. Important services rely on databases, key value stores, message queues, and more. Additionally, relying on one data center or container cluster simply won’t work as apps grow to serve millions of users around the world. Cluster federation allows users to deploy apps across multiple clusters and data centers for scale and resiliency.

You may have [heard me say before](https://www.diamanti.com/blog/the-next-great-application-platform/) that containers are the next great application platform. Diamanti is accelerating container adoption for stateful apps in production - where performance and ease of deployment really matter.   

**Apps Need More Than Cattle**  

Beyond stateless containers like web servers (so-called “cattle” because they are interchangeable), users are increasingly deploying stateful workloads with containers to benefit from “build once, run anywhere” and to improve bare metal efficiency/utilization. These “pets” (so-called because each requires special handling) bring new requirements including longer life cycle, configuration dependencies, stateful failover, and performance sensitivity. Container orchestration must address these needs to successfully deploy and scale apps.  

Enter [Pet Set](/docs/user-guide/petset/), a new object in Kubernetes 1.3 for improved stateful application support. Pet Set sequences through the startup phase of each database replica (for example), ensuring orderly master/slave configuration. Pet Set also simplifies service discovery by leveraging ubiquitous DNS SRV records, a well-recognized and long-understood mechanism.  

Diamanti’s [FlexVolume contribution](https://github.com/kubernetes/kubernetes/pull/13840) to Kubernetes enables stateful workloads by providing persistent volumes with low-latency storage and guaranteed performance, including enforced quality-of-service from container to media.