For the latest stable version, please use Spring Cloud Kubernetes 3.2.0!

Kubernetes Ecosystem Awareness

All features described earlier in this guide work equally well, regardless of whether your application is running inside Kubernetes. This is really helpful for development and troubleshooting. From a development point of view, this lets you start your Spring Boot application and debug one of the modules that is part of this project. You need not deploy it in Kubernetes, as the code of the project relies on the Fabric8 Kubernetes Java client, which is a fluent DSL that can communicate by using http protocol to the REST API of the Kubernetes Server.

Kubernetes awareness is based on Spring Boot API, specifically on ConditionalOnCloudPlatform. That property will auto-detect if your application is currently deployed in kubernetes or not. It is possible to override that setting via spring.main.cloud-platform.

For example, if you need to test some features, but do not want to deploy to a cluster, it is enough to set the: spring.main.cloud-platform=KUBERNETES. This will make spring-cloud-kubernetes act as-if it is deployed in a real cluster.

If you have spring-cloud-starter-bootstrap on your classpath or are setting spring.cloud.bootstrap.enabled=true then you will have to set spring.main.cloud-platform should be set in bootstrap.{properties|yml} (or the profile specific one). Also note that these properties: spring.cloud.kubernetes.config.enabled and spring.cloud.kubernetes.secrets.enabled will only take effect when set in bootstrap.{properties|yml} when you have spring-cloud-starter-bootstrap on your classpath or are setting spring.cloud.bootstrap.enabled=true.

Breaking Changes In 3.0.x

In versions of Spring Cloud Kubernetes prior to 3.0.x, Kubernetes awareness was implemented using spring.cloud.kubernetes.enabled property. This property was removed and is un-supported. Instead, we use Spring Boot API: ConditionalOnCloudPlatform. If it is needed to explicitly enable or disable this awareness, use spring.main.cloud-platform=NONE/KUBERNETES.

Another breaking change is the additional list verb needed for loading configmaps/secrets. For example:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: cluster-role
rules:
  - apiGroups: ["", "extensions", "apps", "discovery.k8s.io"]
    resources: ["configmaps", "pods", "services", "endpoints", "secrets", "endpointslices"]
    verbs: ["get", "list", "watch"]

Kubernetes Profile Autoconfiguration

When the application runs as a pod inside Kubernetes, a Spring profile named kubernetes automatically gets activated. This lets you customize the configuration, to define beans that are applied when the Spring Boot application is deployed within the Kubernetes platform (for example, different development and production configuration).

Istio Awareness

When you include the spring-cloud-kubernetes-fabric8-istio module in the application classpath, a new profile is added to the application, provided the application is running inside a Kubernetes Cluster with Istio installed. You can then use spring @Profile("istio") annotations in your Beans and @Configuration classes.

The Istio awareness module uses me.snowdrop:istio-client to interact with Istio APIs, letting us discover traffic rules, circuit breakers, and so on, making it easy for our Spring Boot applications to consume this data to dynamically configure themselves according to the environment.