Make sure that Spring Boot versions are available

Closes spring-iogh-1214

initializr-service-sample/README.adoc

@@ -43,8 +43,24 @@ If you have the `spring` CLI installed, you can also use it as follows:
 Finally, you can configure your IDE to point to another service instance.
 
 == Configuration
-The configuration in `application.yml` is very simple with a single `web` dependency that
-brings `spring-boot-starter-web`. You can experiment by adding more dependencies or other
-elements that drive how projects are generated.
+There are two main customizations to the sample.
+
+=== Metadata Update Strategy
+First, `ServiceApplication` has a dedicated strategy to update the metadata with the available Spring Boot versions from Sagan (`spring.io`).
+When you issue your first request, you should see something like the following:
+
+[indent=0]
+----
+Fetching Spring Boot metadata from https://spring.io/project_metadata/spring-boot
+----
+
+On further request, you won't see this log entry as the content is cached.
+There are no expiration set, so the available versions won't change until you restart the service.
+
+=== Basic Metadata
+The configuration in `application.yml` is very simple with a single `web` dependency that brings `spring-boot-starter-web`.
+The default `groupId` for generated projects has been customized to `org.acme`.
+
+You can experiment by adding more dependencies or other elements that drive how projects are generated.
 
 

initializr-service-sample/src/main/java/sample/service/ServiceApplication.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,9 +16,14 @@
 
 package sample.service;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.spring.initializr.web.support.SaganInitializrMetadataUpdateStrategy;
+
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.web.client.RestTemplateBuilder;
 import org.springframework.cache.annotation.EnableCaching;
+import org.springframework.context.annotation.Bean;
 import org.springframework.scheduling.annotation.EnableAsync;
 
 /**
@@ -35,4 +40,11 @@ public static void main(String[] args) {
 		SpringApplication.run(ServiceApplication.class, args);
 	}
 
+	// This bean opt-in for fetching available Spring Boot versions from Sagan (spring.io)
+	@Bean
+	SaganInitializrMetadataUpdateStrategy saganInitializrMetadataUpdateStrategy(RestTemplateBuilder restTemplateBuilder,
+			ObjectMapper objectMapper) {
+		return new SaganInitializrMetadataUpdateStrategy(restTemplateBuilder.build(), objectMapper);
+	}
+
 }