Refactor VaultServerInstanceProvider into interface.

We now provide a VaultServerInstanceProvider interface with a default implementation based on DiscoveryClient as bean.

See gh-186.

spring-cloud-vault-config/src/main/java/org/springframework/cloud/vault/config/DiscoveryClientVaultBootstrapConfiguration.java

@@ -50,18 +50,21 @@ public class DiscoveryClientVaultBootstrapConfiguration {
 
 	private final VaultProperties vaultProperties;
 
-	private final VaultServerInstanceProvider instanceProvider;
-
-	public DiscoveryClientVaultBootstrapConfiguration(VaultProperties vaultProperties,
-			DiscoveryClient discoveryClient) {
-
+	public DiscoveryClientVaultBootstrapConfiguration(VaultProperties vaultProperties) {
 		this.vaultProperties = vaultProperties;
-		this.instanceProvider = new VaultServerInstanceProvider(discoveryClient);
 	}
 
 	@Bean
 	@ConditionalOnMissingBean
-	public VaultEndpointProvider vaultEndpointProvider() {
+	public VaultServiceInstanceProvider vaultServerInstanceProvider(
+			DiscoveryClient discoveryClient) {
+		return new DiscoveryClientVaultServiceInstanceProvider(discoveryClient);
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	public VaultEndpointProvider vaultEndpointProvider(
+			VaultServiceInstanceProvider instanceProvider) {
 
 		final String serviceId = this.vaultProperties.getDiscovery().getServiceId();
 
@@ -86,12 +89,6 @@ public class DiscoveryClientVaultBootstrapConfiguration {
 			vaultEndpoint.setScheme(server.isSecure() ? "https" : fallbackScheme);
 		}
 
-		return new VaultEndpointProvider() {
-
-			@Override
-			public VaultEndpoint getVaultEndpoint() {
-				return vaultEndpoint;
-			}
-		};
+		return () -> vaultEndpoint;
 	}
 }

spring-cloud-vault-config/src/main/java/org/springframework/cloud/vault/config/DiscoveryClientVaultServiceInstanceProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 the original author or authors.
+ * Copyright 2018 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.
@@ -31,11 +31,13 @@ import org.springframework.cloud.client.discovery.DiscoveryClient;
  */
 @CommonsLog
 @RequiredArgsConstructor
-class VaultServerInstanceProvider {
+public class DiscoveryClientVaultServiceInstanceProvider implements
+		VaultServiceInstanceProvider {
 
 	private final DiscoveryClient client;
 
-	ServiceInstance getVaultServerInstance(String serviceId) {
+	@Override
+	public ServiceInstance getVaultServerInstance(String serviceId) {
 
 		log.debug("Locating Vault server (" + serviceId + ") via discovery");
 

spring-cloud-vault-config/src/main/java/org/springframework/cloud/vault/config/VaultServiceInstanceProvider.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2017-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.cloud.vault.config;
+
+import org.springframework.cloud.client.ServiceInstance;
+
+/**
+ * Provider interface to obtain a {@link ServiceInstance} to look up the Vault service.
+ *
+ * @author Mark Paluch
+ * @since 1.1
+ */
+@FunctionalInterface
+public interface VaultServiceInstanceProvider {
+
+	/**
+	 * Lookup {@link ServiceInstance} by {@code serviceId}.
+	 *
+	 * @param serviceId the service Id.
+	 * @return {@link ServiceInstance} for the given {@code serviceId}.
+	 * @throws IllegalStateException if no service with {@code serviceId} was found.
+	 */
+	ServiceInstance getVaultServerInstance(String serviceId);
+}