This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Cloud Kubernetes 3.1.3! |
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 .
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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.