Introduction
Spring Cloud Starter Kubernetes Config is a Spring Cloud module that helps developers configure applications in Kubernetes. This module provides access to ConfigMaps and Secrets as externalized configuration.
The module is part of the Spring Cloud Kubernetes project and is based on the familiar Spring Environment abstraction. Using Spring Cloud Starter Kubernetes Config makes it easy to access Kubernetes configuration directly from Spring applications.
Core Concepts
Spring Cloud Starter Kubernetes Config enables access to type-safe configuration information stored in Kubernetes ConfigMaps or the underlying Key-Value stores. Config items are retrieved based on the application.yml which will be present in the classpath of an application. As part of this bootstrapping process, a corresponding KubernetesConfigMapPropertySource will be produced and added to the Spring environment.
The actual values for each property are provided in the corresponding ConfigMap object. The exact configuration format (YAML, JSON, etc.) is not relevant — what matters is this Kubernetes property source is able to resolve any property if the same key is declared in different formats.
Getting Started
The following are the steps to get started with Spring Cloud Starter Kubernetes Config.
1.Add Dependency: Add the following dependency to your project's pom.xml file:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-kubernetes-config</artifactId>
</dependency>
2.Retrieve ConfigMap: Retrieve the relevant ConfigMap from Kubernetes using the Spring Kubernetes Client.
3.Enable KubernetesConfigMapPropertySource: Enable the KubernetesConfigMapPropertySource bean in your Spring application configuration by adding the following code to your configuration class.
@Bean
@ConditionalOnMissingBean
public static KubernetesConfigMapPropertySource kubernetesConfigMapPropertySource() {
return new KubernetesConfigMapPropertySource();
}
4.Use the Environment abstraction: Once the KubernetesConfigMapPropertySource is enabled, the Environment abstraction can be used to access property values or other configuration items stored in the ConfigMap.
FAQ
Q1. What is Spring Cloud Starter Kubernetes Config?
A1. Spring Cloud Starter Kubernetes Config is a Spring Cloud module that provides access to ConfigMaps and Secrets as externalized configuration from Kubernetes. It is based on the familiar Spring Environment abstraction and makes it easy for developers to access Kubernetes configuration directly from their Spring applications.
Q2. How do I add the dependency for spring-cloud-starter-kubernetes-config?
A2. To add the dependency for spring-cloud-starter-kubernetes-config you will need to add the following to your pom.xml:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-kubernetes-config</artifactId>
</dependency>
Q3. How do I retrieve a ConfigMap in Kubernetes?
A3. You can retrieve the relevant ConfigMap from Kubernetes using the Spring Kubernetes Client library. It provides a comprehensive API for interacting with Kubernetes objects.
Q4. How do I enable the KubernetesConfigMapPropertySource bean?
A4. You can enable the KubernetesConfigMapPropertySource bean in your Spring application configuration by adding the following code to your configuration class.
@Bean
@ConditionalOnMissingBean
public static KubernetesConfigMapPropertySource kubernetesConfigMapPropertySource() {
return new KubernetesConfigMapPropertySource();
}
Q5. How can I use the Environment abstraction to access the property values in my ConfigMap?
A5. Once the KubernetesConfigMapPropertySource is enabled, the Environment abstraction can be used to access property values or other configuration items stored in the ConfigMap. You can then use its various methods (getProperty, getRequiredProperty, containsProperty, etc) to access the property values.
Summary
Spring Cloud Starter Kubernetes Config provides an easy way for developers to access ConfigMaps and Secrets as externalized configuration in their applications. It is based on the familiar Spring Environment abstraction and makes it easy to access Kubernetes configuration directly from Spring applications. To get started, add the dependency for spring-cloud-starter-kubernetes-config, retrieve the relevant ConfigMap from Kubernetes, enable the KubernetesConfigMapPropertySource bean, and then use the Environment abstraction to access the property values in your ConfigMap.