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An Introduction to Spring Cloud Config

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by

Editorial Team
in

1. Introduction

Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system.

Spring Boot documentation

Spring Cloud Config is a subproject within the broader Spring Cloud framework, which is designed to simplify the development of distributed systems and microservices. Spring Cloud Config specifically focuses on the configuration management aspects of microservices architecture. It provides a centralized configuration service that allows you to manage and distribute configuration settings for various components in a distributed system.

Spring Cloud Config Server is a component of the Spring Cloud framework designed to address the challenges associated with configuring and managing microservices in a distributed system. The Config Server enables you to centrally manage external properties for application across all environments. There are many ways to manage the application properties, such as git, file system etc. By default, implementation of the server storage backend uses git, but you can easily add alternative implementation and plug them in with Spring configuration.

2. Need of Spring Cloud Config Server

Spring Cloud Config Server is essential due to various common requirements of microservices architectures:

  1. Centralized Configuration Management: Microservices usually need configuration parameters for operation, and managing these configurations across multiple services and environments can be challenging. Spring Cloud Config Server provides a centralized solution for storing and managing configuration properties for various microservices.
  2. Dynamic Configuration Updates: Spring Cloud Config Server supports dynamic updates, allowing changes to configurations to take effect without requiring a restart of the microservices.
  3. Environment-Specific Configurations: Microservices may need different configurations for different environments, such as development, testing and production. Spring Cloud Config Server enables the separation of configuration for different environments, making it easier to manage and deploy services across various stages.
  4. Versioning and History: Maintaining a record of configuration modifications, implementing version control, and preserving a history of configurations are crucial for auditing, troubleshooting, and reverting changes. Spring Cloud Config Server offers versioning and historical tracking capabilities, enabling teams to comprehend the timing and reasons behind configuration modifications.
  5. Security and Encryption: Spring Cloud Config Server facilitates the encryption and decryption of sensitive configuration properties, ensuring that sensitive information is not exposed in plaintext. This is particularly critical when handling credentials, API keys, or other private data.
  6. Integration with Spring Boot Applications: Spring Cloud Config Server integrates seamlessly with Spring Boot applications, simplifying adoption and usage for developers who are well-versed in the Spring ecosystem.
  7. Multiple Sources for Configuration: Spring Cloud Config Server has the capability to retrieve configurations from diverse sources, such as version control systems (e.g., Git), local file systems, and alternative storage solutions. This flexibility allows teams to choose the source that best fits their workflow and infrastructure.
  8. Microservices Scaling: With the increase in number of microservices, manually managing configurations becomes impractical. Spring Cloud Config Server addresses this challenge by offering a scalable and centralized solution, streamlining the process.

3. Configuration

The Spring Cloud Config Server is embeddable in a Spring Boot application. Add the following dependency to your pom.xml for Spring Cloud Config Server:

	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-config-server</artifactId>
	</dependency>

Spring Cloud Config Server provides an HTTP resource-based API for external configuration (name-value pairs or equivalent YAML content). To embed the Spring Cloud Config Server in a Spring Boot application use the @EnableConfigServer annotation.

@SpringBootApplication
@EnableConfigServer
public class ConfigServer {
  public static void main(String[] args) {
    SpringApplication.run(ConfigServer.class, args);
  }
}

3. HTTP Service endpoints

The HTTP service has resources in the following form:

  • /{application}/{profile}[/{label}]
  • /{application}-{profile}.yml
  • /{label}/{application}-{profile}.yml
  • /{application}-{profile}.properties
  • /{label}/{application}-{profile}.properties

where application is injected as the spring.config.name in the SpringApplication, profile is an active profile (or comma-separated list of properties), and label is an optional git label (if case of default and defaults to master.)

The HTTP client server picks up the external configuration from the default local config server (if it is running) on port 8888. To modify the startup behavior, you can change the location of the config server by using application.properties as shown in the following example:

spring.config.import=optional:configserver:http://myconfigserver.com

By default, if no application name is set, application will be used. To modify the name, the following property can be added to the application.properties file:

spring.application.name: myapp

4. Conclusion

In conclusion, this tutorial has provided a comprehensive overview of Spring Cloud Config, a vital component in the Spring Cloud ecosystem for managing configurations in microservices architectures. We’ll see the implementation of the Spring Cloud Config in upcoming tutorials.