The Blas from Pas: java-cfenv : A library for accessing Cloud Foundry Services on the new Tanzu Application Service for Kubernetes

Thursday, 3 September 2020

java-cfenv : A library for accessing Cloud Foundry Services on the new Tanzu Application Service for Kubernetes

The Spring Cloud Connectors library has been with us since the launch event of Cloud Foundry itself back in 2011. This library would create the required Spring Beans from bound VCAP_SERVICE ENV variable from a pushed Cloud Foundry Application such as connecting to databases for example. The java buildpack then replaces these bean definitions you had in your application with those created by the connector library through a feature called ‘auto-reconfiguration’

Auto-reconfiguration is great for getting started. However, it is not so great when you want more control, for example changing the size of the connection pool associated with a DataSource.

With the up coming Tanzu Application Service for Kubernetes the original Cloud Foundry buildpacks are now replaced with the new Tanzu Buildpacks which are based on the Cloud Native Buildpacks CNCF Sandbox project. As a result of this auto-reconfiguration is no longer included in java cloud native buildpacks which means auto-configuration for the backing services is no longer available.

So is their another option for this? The answer is "Java CFEnv". This provide a simple API for retrieving credentials from the JSON strings contained inside the VCAP_SERVICES environment variable.

https://github.com/pivotal-cf/java-cfenv

So if you after exactly how it worked previously all you need to do is add this maven dependancy to your project as shown below.

  
        <dependency>
            <groupId>io.pivotal.cfenv</groupId>
            <artifactId>java-cfenv-boot</artifactId>
        </dependency>

Of course this new library is much more flexible then this and by using the class CfEnv as the entry point to the API for accessing Cloud Foundry environment variables your free to use the Spring Expression Language to invoke methods on the bean of type CfEnv to set properties for example plus more.

For more information read the full blog post as per below

https://spring.io/blog/2019/02/15/introducing-java-cfenv-a-new-library-for-accessing-cloud-foundry-services

Finally this Spring Boot application is an example of using this new library with an application deployed to the new Tanzu Application Service for Kubernetes.

https://github.com/papicella/spring-book-service