This is an example spring cloud function project running on Fn using the SpringCloudFunctionInvoker.

Firstly, if you have used fn before you'll want to make sure you have the latest runtime image which includes the Spring support:

$ docker pull fnproject/fdk-java:latest

Then you can build and deploy the app

fn build
fn deploy --local --app spring-cloud-fn

# Set up a couple of routes for different functions
fn routes create spring-cloud-fn /upper
fn routes config set spring-cloud-fn /upper FN_SPRING_FUNCTION upperCase

fn routes create spring-cloud-fn /lower
fn routes config set spring-cloud-fn /lower FN_SPRING_FUNCTION lowerCase

Now you can call those functions using fn call or curl:

$ echo "Hi there" | fn call spring-cloud-fn /upper
HI THERE

$ curl -d "Hi There" http://localhost:8080/r/spring-cloud-fn/lower
hi there

@Configuration

Defines that the class is a Spring configuration class with @Bean definitions inside of it.

@Import(ContextFunctionCatalogAutoConfiguration.class)

Specifies that this configuration uses a InMemoryFunctionCatalog that provides the beans necessary for the SpringCloudFunctionInvoker.

    ...
    @FnConfiguration
    public static void configure(RuntimeContext ctx) {
        ctx.setInvoker(new SpringCloudFunctionInvoker(SCFExample.class));
    }

Sets up the Fn Java FDK to use the SpringCloudFunctionInvoker which performs function discovery and invocation.

    // Unused - see https://github.com/fnproject/fdk-java/issues/113
    public void handleRequest() { }

Currently the runtime expects a method to invoke, however this isn't used in the SpringCloudFunctionInvoker so we declare an empty method simply to keep the runtime happy. This will not be necessary for long - see the linked issue on GitHub.

    @Bean
    public Function<String, String> upperCase(){
        return String::toUpperCase;
    }

    @Bean
    public Function<String, String> lowerCase(){
        return String::toLowerCase;
    }

Finally the heart of the configuration; the bean definitions of the functions to invoke.

Note that these methods are not the functions themselves. They are factory methods which return the functions. As the Beans are constructed by Spring it is possible to use @Autowired dependency injection.