What is kubernetes operator
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- WHAT IS KUBERNETES OPERATOR HOW TO
- WHAT IS KUBERNETES OPERATOR SOFTWARE
- WHAT IS KUBERNETES OPERATOR CODE
The downside: It has a steep learning curve if you don’t understand the Go programming language.
WHAT IS KUBERNETES OPERATOR CODE
The benefit: It uses the same resources as your built-in resources so you can rest easy knowing that the code is tested and versioned according to k8s standards.ClientGo connects to the Kubernetes API.There are several ways to build an operator: Use an operator whenever you need to build a tool that watches your applications for changes and perform certain SRE/Ops tasks when certain things happen.This allows automation around your application built into the k8s ecosystem. Use an operator whenever you need to encapsulate your stateful application business logic controlling everything with Kubernetes API.For a controller to be considered an operator, it must have application domain knowledge in it to perform automated tasks on behalf of the user (SRE/Ops engineer). It is important to know that all operators are controllers but not all controllers are operators. So, why aren’t those built-in controllers called operators? Because those controllers are not specific to a particular application they are upstream controllers used with built-in resources, like deployment, jobs, etc. The controller sees that the number of pods you desire does not match the current state, so it spins another one up to match the desired state. As a matter of fact, we are already using some form of controller already built into k8s.Ī good example is a deployment wherein you kill a pod, and another one spins up. Custom controllerĪ controller is a control loop that watches the cluster for changes to a specific resource (custom resource) and makes sure that the current state matches the desired state. A custom resource is simply a resource that does not come bundled with k8s out of the box.
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When you write a manifest, you have to specify a kind (pod or deployment) in the yaml file. After that, we can use kubectl to access our object just like any other built-in object. It allows us to extend k8s by adding more objects of a kind to the cluster.
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In Kubernetes, a resource is an endpoint in the k8s API that stores a bunch of API objects of a specific kind. Operator is built on two key principles of Kubernetes: a custom resource and a custom controller. This is exactly what k8s operators do: act on behalf of the user when you need to perform certain tasks that an SRE/Ops engineer normally has to perform. How these tasks are achieved varies depending on the application itself and the business use case (domain knowledge). Site reliability engineers and operational engineers are often tasked with, or interested in, automating things like backup, updates, data restore, etc. So, in our example, we can apply what we know about how the application relates to the database and create a controller that will do certain things when the application behaves in a certain way. To understand an operator, think of the stateful part of the setup-the database or any application that stores data, like etcd. Ideally, you’d want to run something like a “deployment” for the java app exposed with a service, and for the backend, run a “statefulset” for the database application. You want to deploy that to your k8s cluster. Say you have a java app that connects to a database. If you are new to Kubernetes, the idea of an operator can be confusing, so let’s look at a simple example. Using a Kubernetes operator means you can operate a stateful application by writing a custom controller with domain specific knowledge built into it. Use the right-hand menu to navigate.) Understanding the K8S operator (This article is part of our Kubernetes Guide. In this article, I’ll shed light on the operator pattern, including how it applies to Kubernetes, when to use it, and some tools to help get started with creating one. Those same engineers like to automate repeatable tasks-and the operator pattern is essential to this automation.
WHAT IS KUBERNETES OPERATOR HOW TO
Engineers who use Kubernetes have a unique perspective on how apps and services should behave, and how to react when problems arise.
WHAT IS KUBERNETES OPERATOR SOFTWARE
A software extension to Kubernetes, operators function by capturing the knowledge of a human operator.