kubernetes-discovery-spring

Kubernetes Service Discovery for Spring Cloud and Ribbon

Compatible with Spring Boot 2.1.0 and Spring Cloud Greenwich

Overview

This library provides implementations of Spring Cloud's DiscoveryClient class and Ribbon's ServerList. It is compatible with Spring Cloud Greenwich and is meant to be a very thin integration layer between Kubernetes and Spring Cloud + Ribbon.

Compared to other integrations, this one still leaves the actual load balancing on kubernetes. Its purpose is discover to services and provide seamless transition between other Ribbon providers like Eureka. That means, that you can still use @LoadBalanced RestTemplate while avoiding problems with stale Pod IPs during rolling update of a deployment or other changes to Service-to-Pod mapping in Kubernetes.

Under the hood, the library makes use of fabric8's kubernetes-client Java library to communicate with the Kubernetes cluster.

Made with ❤️ in Prague by DT>Force.

Quick Start

Maven

<dependencies>
    <dependency>
        <groupId>com.dtforce</groupId>
        <artifactId>kubernetes-discovery-spring</artifactId>
        <version>1.1.0</version>
    </dependency>
</dependencies>

Gradle

dependencies {
    compile 'com.dtforce:kubernetes-discovery-spring:1.1.0'
}

Label-based filtering

Since version 1.1.0, the Kubernetes Discovery Client implements SelectorEnabledDiscoveryClient, a new interface of our own making. This interface, a subset of the vanilla DiscoveryClient, allows developers to go beyong traditional name-based instance discovery by providing methods to get instances based on their metadata.

In kubernetes-discovery-spring, the selector-enabled Discovery Client implementation filters services by equality-based Label matching. The interface methods can be provided with labels to match and labels to not match.

Configuration

Kubernetes API credentials

Because kubernetes-discovery-spring uses the great kubernetes-client library from fabric8.io, when running in a Pod no special configuration is needed to establish communications with Kubernetes' API. A default Service Account token and CA are automatically mounted as files in K8S containers and picked up by kubernetes-client.

It can also get API credentials from kubectl configuration files, Spring config properties and environment variables. See the official documentation of kubernetes-client here for more details: https://github.com/fabric8io/kubernetes-client

Spring Configuration properties

• spring.cloud.kubernetes.enabled (boolean) : Enable/disable the whole library integration - if set to true, bean of KubernetesClient(fabric8) is registered, if one does not exist. (default=false)
• spring.cloud.kubernetes.discovery.enabled (boolean) : Enable/disable Spring Cloud Discovery integration. (default=false)
• spring.cloud.kubernetes.ribbon.enabled (boolean) : Enable/disable Ribbon integration. (default=false)

License

This code is licensed under the Apache License 2.0.