Extend PCF module to read tags to support user-provided services (#2238)

Extend the PCF module to read tags of apps to support user-provided services.

docs/src/main/asciidoc/cloudfoundry.adoc

@@ -22,3 +22,35 @@ This includes both MySQL and PostgreSQL bindings to the same app.
 WARNING: In order for the Cloud SQL integration to work in Cloud Foundry, auto-reconfiguration must be disabled.
 You can do so using the `cf set-env <APP> JBP_CONFIG_SPRING_AUTO_RECONFIGURATION '{enabled: false}'` command.
 Otherwise, Cloud Foundry will produce a `DataSource` with an invalid JDBC URL (i.e., `jdbc:mysql://null/null`).
+
+=== User-Provided Services
+
+https://docs.cloudfoundry.org/devguide/services/user-provided.html[User-provided services] enable developers to use services that are not available in the marketplace with their apps running on Cloud Foundry.
+For example, you may want to use a user-provided service that points to a shared Google Service (like Cloud Spanner) used across your organization.
+
+In order for Spring Cloud GCP to detect your user-provided service as a Google Cloud Service, you must add an https://docs.cloudfoundry.org/devguide/services/managing-services.html#instance-tags-create[instance tag] indicating the Google Cloud Service it uses.
+The tag should simply be the Cloud Foundry name for the Google Service.
+
+For example, if you create a user-provided service using Cloud Spanner, you might run:
+[source, shell]
+----
+$ cf create-user-provided-service user-spanner-service -t "google-spanner" ...
+----
+
+This allows Spring Cloud GCP to retrieve the correct service properties from Cloud Foundry and use them in the auto configuration for your application.
+
+A mapping of Google service names to Cloud Foundry names are provided below:
+
+|===
+| Google Cloud Service | Cloud Foundry Name (add this as a tag)
+| https://cloud.google.com/pubsub[Google Cloud Pub/Sub] | `google-pubsub`
+| https://cloud.google.com/storage[Google Cloud Storage] | `google-storage`
+| https://cloud.google.com/spanner[Google Cloud Spanner] | `google-spanner`
+| https://cloud.google.com/datastore[Datastore] | `google-datastore`
+| https://cloud.google.com/firestore[Firestore] | `google-firestore`
+| https://cloud.google.com/bigquery[BigQuery] | `google-bigquery`
+| https://cloud.google.com/products/operations[Stackdriver Trace] | `google-stackdriver-trace`
+| https://cloud.google.com/sql[Cloud Sql (MySQL)] | `google-cloudsql-mysql`
+| https://cloud.google.com/sql[Cloud Sql (PostgreSQL)] | `google-cloudsql-postgres`
+|===
+

spring-cloud-gcp-cloudfoundry/src/main/java/org/springframework/cloud/gcp/cloudfoundry/GcpCloudFoundryEnvironmentPostProcessor.java

@@ -126,13 +126,16 @@ private static Properties retrieveCfProperties(CfEnv cfEnv,
 		try {
 			List<CfService> serviceBindings = cfEnv.findServicesByLabel(cfServiceName);
 
-			if (serviceBindings == null) {
-				return properties;
+			// If finding by label fails, attempt to find the service by tag.
+			if (serviceBindings.isEmpty()) {
+				serviceBindings = cfEnv.findServicesByTag(cfServiceName);
 			}
 
 			if (serviceBindings.size() != 1) {
-				LOGGER.warn("The service " + cfServiceName + " has to be bound to a "
-						+ "Cloud Foundry application once and only once.");
+				if (serviceBindings.size() > 1) {
+					LOGGER.warn("The service " + cfServiceName + " has to be bound to a "
+							+ "Cloud Foundry application once and only once.");
+				}
 				return properties;
 			}
 

spring-cloud-gcp-cloudfoundry/src/test/java/org/springframework/cloud/gcp/cloudfoundry/GcpCloudFoundryEnvironmentPostProcessorTests.java

@@ -125,6 +125,20 @@ public void test2Sqls() throws IOException {
 				.isEqualTo("test-key");
 	}
 
+	@Test
+	public void testUserProvidedServices() throws IOException {
+		String vcapFileContents = new String(Files.readAllBytes(
+				new ClassPathResource("VCAP_SERVICES_USER_PROVIDED").getFile().toPath()));
+		mockVcapServices(vcapFileContents);
+
+		this.initializer.postProcessEnvironment(this.context.getEnvironment(), null);
+
+		assertThat(getProperty("spring.cloud.gcp.spanner.project-id"))
+				.isEqualTo("spanner-project-id");
+		assertThat(getProperty("spring.cloud.gcp.spanner.instance-id"))
+				.isEqualTo("spanner-instance");
+	}
+
 	private String getPrivateKeyDataFromJson(String json, String serviceName) {
 		JsonParser parser = JsonParserFactory.getJsonParser();
 		Map<String, Object> vcapMap = parser.parseMap(json);

spring-cloud-gcp-cloudfoundry/src/test/resources/VCAP_SERVICES_USER_PROVIDED

@@ -0,0 +1,21 @@
+{
+  "user-provided": [
+    {
+      "label": "user-provided",
+      "name": "supply-spanner-service",
+      "tags": ["google-spanner"],
+      "instance_name": "supply-spanner-service",
+      "binding_name": null,
+      "credentials": {
+        "Email": "hello-world@gmail.com",
+        "Name": "hello-world",
+        "PrivateKeyData": "xxxxxxxxx",
+        "ProjectId": "spanner-project-id",
+        "instance_id": "spanner-instance",
+        "UniqueId": "xxxxxxxxxx"
+      },
+      "syslog_drain_url": "",
+      "volume_mounts": []
+    }
+  ]
+}