Developing Kubernetes Operators

Kubernetes, as a container orchestration platform, has revolutionized the way we deploy and manage applications. While Kubernetes offers a robust framework for running containers at scale, managing complex applications that serve millions of users can be an intimidating task.

Nowadays, is not often that we run applications on only one server. Today, applications are made up of many small parts that can grow or shrink as needed running distributed in several machines or services, locally or in the cloud. Managing all these components can become difficult without automation, which is why self-healing apps are becoming a necessity for operations teams.

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What is a Kubernetes Operator?

A Kubernetes Operator is a method of packaging, deploying, and managing applications on Kubernetes clusters with automation in mind. They are software components that automate tasks such as configuration, updates, scaling, and recovery.

Operators use a set of Kubernetes APIs and patterns to handle the entire lifecycle of a particular application or service. They are especially useful when dealing with stateful applications or services that require more than basic deployment and scaling logic.

One of the most significant advantages of Kubernetes Operators is their ability to manage applications across multiple clusters, making them valuable assets for scenarios like multi-cloud deployments or hybrid cloud setups.

The core components of a Kubernetes Operator are:

  1. Custom Resource Definitions (CRDs): These extend the Kubernetes API to define new types of resources specific to your application. CRDs allow you to define the structure and behavior of your application within the Kubernetes ecosystem.

  2. Controller Logic: The controller watches for changes to custom resources (CRs) created based on the defined CRDs. When a CR is created, updated, or deleted, the controller reconciles the actual state of the application with the desired state defined in the CR.

  3. Reconciliation Loop: The reconciliation loop continuously compares the current state of the application with the desired state defined in the CR. If there is a discrepancy, the operator takes the necessary actions to align the two states.

  4. Custom Logic: Operators often include custom logic of the specific application being managed. This can involve tasks such as application-specific scaling, data migration, backup and restore, and more.

Learn more about Kubernetes Operators in this Kubernetes Operators Explained guide.


To implement Kubernetes Operators, there are multiple frameworks available. One notable option is the Operator Framework SDK, which provides open-source libraries for creating operators using Go, Ansible, Helm, and, as of April 2023, Java with the Java Operator SDK.

Introducing the Java Operator SDK

This framework empowers developers to build Kubernetes Operators using Java. It’s especially convenient for platforms developed using Java or any of the JVM languages. You can learn more about it in this Red Hat article.

Some key benefits of using the Java Operator SDK for managing your Kubernetes applications are:

  • Automation: The Java Operator SDK abstracts away much of the complexity of interacting with the Kubernetes API, allowing you to focus on defining how your application should behave.

  • Consistency: With operators, you ensure that your application’s behavior is consistent across different environments, which is invaluable in complex microservices architectures.

  • Scalability: Operators are designed to work well with large-scale applications. As your application grows, the operator can handle the increased load and management tasks.

  • Customization: You have full control over how your operator behaves and how it interacts with your application.

Kubernetes Operators, coupled with the Java Operator SDK, supply a powerful toolkit for simplifying the management of complex applications in Kubernetes clusters. They bring automation, consistency, scalability, and customization to the forefront, ensuring that your applications run smoothly in any Kubernetes environment.