Recognize Consumer<ServerBuilder> beans for spring autoconfiguration (#…

…2070)

I think it's useful to be able to customize with spring without using custom types, for example to allow creating a plugin module that just configures a server without needing to worry about armeria-spring. It's sort of similar to how Spring supports both custom annotations and `javax.inject` annotaions. 

Idea came up in openzipkin-contrib/zipkin-storage-kafka#38

spring/boot-autoconfigure/src/main/java/com/linecorp/armeria/spring/ArmeriaAutoConfiguration.java

@@ -27,6 +27,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+import java.util.function.Consumer;
 
 import javax.annotation.Nullable;
 
@@ -70,6 +71,7 @@ public Server armeriaServer(
             Optional<MeterIdPrefixFunctionFactory> meterIdPrefixFunctionFactory,
             Optional<List<HealthChecker>> healthCheckers,
             Optional<List<ArmeriaServerConfigurator>> armeriaServerConfigurators,
+            Optional<List<Consumer<ServerBuilder>>> armeriaServerBuilderConsumers,
             Optional<List<ThriftServiceRegistrationBean>> thriftServiceRegistrationBeans,
             Optional<List<GrpcServiceRegistrationBean>> grpcServiceRegistrationBean,
             Optional<List<HttpServiceRegistrationBean>> httpServiceRegistrationBeans,
@@ -123,6 +125,10 @@ public Server armeriaServer(
                 configurators -> configurators.forEach(
                         configurator -> configurator.configure(server)));
 
+        armeriaServerBuilderConsumers.ifPresent(
+                consumers -> consumers.forEach(
+                        consumer -> consumer.accept(server)));
+
         if (!Strings.isNullOrEmpty(docsPath)) {
             server.serviceUnder(docsPath, docServiceBuilder.build());
         }

spring/boot-autoconfigure/src/test/java/com/linecorp/armeria/spring/ArmeriaAutoConfigurationWithConsumerTest.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2019 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you 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:
+ *
+ *   https://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 com.linecorp.armeria.spring;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.concurrent.TimeUnit;
+import java.util.function.Consumer;
+
+import javax.inject.Inject;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.DisableOnDebug;
+import org.junit.rules.TestRule;
+import org.junit.rules.Timeout;
+import org.junit.runner.RunWith;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import com.linecorp.armeria.client.HttpClient;
+import com.linecorp.armeria.common.AggregatedHttpResponse;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.common.HttpStatus;
+import com.linecorp.armeria.server.Server;
+import com.linecorp.armeria.server.ServerBuilder;
+import com.linecorp.armeria.spring.ArmeriaAutoConfigurationWithConsumerTest.TestConfiguration;
+
+/**
+ * This uses {@link ArmeriaAutoConfiguration} for integration tests.
+ * application-autoConfTest.yml will be loaded with minimal settings to make it work.
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = TestConfiguration.class)
+@ActiveProfiles({ "local", "autoConfTest" })
+public class ArmeriaAutoConfigurationWithConsumerTest {
+
+    @SpringBootApplication
+    @Import(ArmeriaOkServiceConfiguration.class)
+    public static class TestConfiguration {
+        @Bean
+        public Consumer<ServerBuilder> customizer() {
+            return sb -> sb.service("/customizer", ((ctx, req) -> HttpResponse.of(HttpStatus.OK)));
+        }
+    }
+
+    @Rule
+    public TestRule globalTimeout = new DisableOnDebug(new Timeout(10, TimeUnit.SECONDS));
+
+    @Inject
+    private Server server;
+
+    private String newUrl(String scheme) {
+        final int port = server.activeLocalPort();
+        return scheme + "://127.0.0.1:" + port;
+    }
+
+    @Test
+    public void normal() throws Exception {
+        final HttpClient client = HttpClient.of(newUrl("h1c"));
+
+        final HttpResponse response = client.get("/customizer");
+
+        final AggregatedHttpResponse msg = response.aggregate().get();
+        assertThat(msg.status()).isEqualTo(HttpStatus.OK);
+    }
+}