The operator (v5) supports common cloud Kubernetes platforms (GKE, EKS, AKS), VMware Tanzu, Openshift, Rancher, Kubernetes. I used the quick start guide to bring Postgres up real quick on an Azure Kubernetes cluster. The operator will set up the cluster according to the declaration made in the PostgresCluster CR.
#What is kubernetes db install#
To install an instance of PostgreSQL database, we need to install the operator, and then declare a Custom Resource using the PostgresCluster CRD. For PostgreSQL, there are a number of operators, the most notable being PGO ( Postgres Operator) from Crunchy Data. This is a disadvantage of Helm chart as compared with operators. If someone changes the workload after initial installation, the change is not monitored or controlled by any controller. However, it does not have a control loop. A statefulSet names its the Pods by sequential numbers.įor Postgres database, Bitnami built a good Helm Chart to install the database automatically. In a replicaSet, Pod names have extensions of randomly generated numbers. This pattern is also known as the operator pattern. In this case, an operator is an implementation of the controller pattern. CRD can define a custom object type for controller to consume.
#What is kubernetes db how to#
How to orchestrate Pods for stateful workload is usually more tricky. Stateful workloadĭoes the controller pattern also benefit stateful workload? Yes. If there’s one thing that sets Kubernetes apart from other hosting platforms and automation platforms, it is the implementation of controller pattern. Even though Red Hat now brands Ansible as Automation Controller, it does not involve a control loop or controller pattern. Controller is what is missing in many automation tools other that Kubernetes. Here is a good page about how controllers work. Kubernetes comes with a set of build-in controllers that run inside the kube-controller-manager. Kubernetes controller solved all these operational problems. Without a central “Control Plane”, there is no coordination between the activities of each VMs.
However, each server is unaware of the status of its peer. One may wrap the process with process monitor and control utility such as supervisord, and re-install the application using automation utility (e.g. If the process on one of the VMs dies, the VM has to be removed from the load balancer’s target pool. With traditional hosting model on Linux servers, you’d have it installed on all five VMs.
Let’s examine a web service that requires 5 instances behind load balancer. This is a key feature of Kubernetes as container platform. They are the engines of the platform that works tirelessly in a control loop to ensure desired states matches their declared states. As discussed, the controller pattern is adopted in all controller implementations. Kubernetes’ orchestration capability are driven by controllers. Because they don’t carry persistent data themselves, they are expendable. Pods for stateless workload are ephemeral: they crash and get replaced at any time. Built-in objects such as replicaSet, deployment, horizontalPodAutoscaler are abstractions of operations particular to stateless workload. That is what Kubernetes was born to solve. The first few versions of Kubernetes only supported stateless workload (reference documentary). In this post, we discuss what we need to be aware of in order to host database on Kubernetes. If they do, the hard path makes economical sense. The operational cost has to do with whether the client has in-house expertise in database and Kubernetes. Nowadays, for clients with their own Kubernetes platform, technological maturity is no longer the main reason that keeps them from hosting database on Kubernetes, it is the operational cost. Just a few years back, Kubernetes was not mature to host database. While the points in the chapters are valid, the book also includes a good amount of technical details which might lead reader to believe the opposite view. The same voice came from the author of the upcoming book Managing Cloud Native Data on Kubernetes, who also advocates hosting database on Kubernetes. The author explained his journey from being a skeptic, to grudging acceptance, and eventually to an evangelist on running database on Kubernetes. I believed that was the client’s best interest, until I came across this the blog post A Case for Databases on Kubernetes from a Former Skeptic. My thought: it’s doable, but don’t do it unless operating database as a service is your main business. So I did some homework and went through this tutorial. The client appears assertive and reluctant to resort to managed services. “We want to host Postgres database on Kubernetes.
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