Retry when Spring tests fails to start a Server with a random port …

…obtained in advance (#4395)

Motivation:

If a random port (0) for internal services or managed services is
specified in Spring configuration, the Spring integration module
allocate available ports early and use them to configure additional
service later.
https://github.com/line/armeria/blob/948763acc7911c951e37dbd35132edd253ea3934/spring/boot2-actuator-autoconfigure/src/main/java/com/linecorp/armeria/spring/actuate/ArmeriaSpringActuatorAutoConfiguration.java#L258-L260
This is not a problem in production mode.
However, in testing situations, many test servers are started simultaneously 
with a random port and the available ports can be acquired by them. #4391 #4329

Modifications:

- Add `RetryableArmeriaServerGracefulShutdownLifecycle` to retry a
server with a backoff at most N times.

Result:

- This is not a perfect answer for the failure but it might reduce the
  number of failures.
- Fixes #4391 #4329

spring/boot2-autoconfigure/src/main/java/com/linecorp/armeria/spring/AbstractArmeriaAutoConfiguration.java

@@ -107,6 +107,7 @@ public Server armeriaServer(
      * Wrap {@link Server} with {@link SmartLifecycle}.
      */
     @Bean
+    @ConditionalOnMissingBean(SmartLifecycle.class)
     public SmartLifecycle armeriaServerGracefulShutdownLifecycle(Server server) {
         return new ArmeriaServerGracefulShutdownLifecycle(server);
     }

spring/boot2-autoconfigure/src/test/java/com/linecorp/armeria/spring/ArmeriaSettingsConfigurationPriorityTest.java

@@ -24,6 +24,7 @@
 import org.junit.runner.RunWith;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.SmartLifecycle;
 import org.springframework.context.annotation.Bean;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
@@ -46,6 +47,11 @@ static class TestConfiguration {
         ArmeriaServerConfigurator maxNumConnectionsConfigurator() {
             return builder -> builder.maxNumConnections(16);
         }
+
+        @Bean
+        SmartLifecycle smartLifecycle(Server server) {
+            return new RetryableArmeriaServerGracefulShutdownLifecycle(server, 8);
+        }
     }
 
     @Inject

spring/boot2-autoconfigure/src/test/java/com/linecorp/armeria/spring/LocalArmeriaPortHttpsTest.java

@@ -24,6 +24,8 @@
 import org.junit.runner.RunWith;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.SmartLifecycle;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
@@ -50,7 +52,13 @@ public class LocalArmeriaPortHttpsTest {
 
     @SpringBootApplication
     @Import(ArmeriaOkServiceConfiguration.class)
-    static class TestConfiguration {}
+    static class TestConfiguration {
+
+        @Bean
+        SmartLifecycle smartLifecycle(Server server) {
+            return new RetryableArmeriaServerGracefulShutdownLifecycle(server, 8);
+        }
+    }
 
     private static final ClientFactory clientFactory =
             ClientFactory.builder()

spring/boot2-autoconfigure/src/test/java/com/linecorp/armeria/spring/RetryableArmeriaServerGracefulShutdownLifecycle.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2022 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 java.util.concurrent.TimeUnit;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.SmartLifecycle;
+
+import com.google.common.util.concurrent.Uninterruptibles;
+
+import com.linecorp.armeria.client.retry.Backoff;
+import com.linecorp.armeria.common.util.Exceptions;
+import com.linecorp.armeria.server.Server;
+
+/**
+ * A {@link SmartLifecycle} which retries to start the {@link Server} up to {@code maxAttempts}.
+ * This is useful for testing that needs to bind a server to a random port number obtained in advance.
+ */
+final class RetryableArmeriaServerGracefulShutdownLifecycle implements SmartLifecycle {
+
+    private static final Logger logger =
+            LoggerFactory.getLogger(RetryableArmeriaServerGracefulShutdownLifecycle.class);
+
+    private final SmartLifecycle delegate;
+    private final int maxAttempts;
+    private final Backoff backoff;
+
+    RetryableArmeriaServerGracefulShutdownLifecycle(Server server, int maxAttempts) {
+        delegate = new ArmeriaServerGracefulShutdownLifecycle(server);
+        this.maxAttempts = maxAttempts;
+        backoff = Backoff.ofDefault();
+    }
+
+    @Override
+    public void start() {
+        Throwable caughtException = null;
+        for (int i = 1; i <= maxAttempts; i++) {
+            try {
+                delegate.start();
+                return;
+            } catch (Exception ex) {
+                caughtException = Exceptions.peel(ex);
+                if (i < maxAttempts) {
+                    final long delayMillis = backoff.nextDelayMillis(i);
+                    logger.debug("{}; retrying in {} ms (attempts so far: {})",
+                                 ex.getMessage(), delayMillis, i, ex);
+                    Uninterruptibles.sleepUninterruptibly(delayMillis, TimeUnit.MILLISECONDS);
+                }
+            }
+        }
+
+        assert caughtException != null;
+        Exceptions.throwUnsafely(caughtException);
+    }
+
+    @Override
+    public void stop() {
+        delegate.stop();
+    }
+
+    @Override
+    public void stop(Runnable callback) {
+        delegate.stop(callback);
+    }
+
+    @Override
+    public boolean isAutoStartup() {
+        return delegate.isAutoStartup();
+    }
+
+    @Override
+    public int getPhase() {
+        return delegate.getPhase();
+    }
+
+    @Override
+    public boolean isRunning() {
+        return delegate.isRunning();
+    }
+}

spring/boot2-autoconfigure/src/test/java/com/linecorp/armeria/spring/RetryableArmeriaServerGracefulShutdownLifecycleTest.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2022 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.assertThatThrownBy;
+import static org.awaitility.Awaitility.await;
+
+import java.io.IOException;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.junit.Test;
+import org.springframework.context.SmartLifecycle;
+
+import com.linecorp.armeria.common.CommonPools;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.server.Server;
+
+public class RetryableArmeriaServerGracefulShutdownLifecycleTest {
+
+    @Test
+    public void retryStarting() throws InterruptedException {
+        final Server dummyServer = Server.builder()
+                                         .service("/", (ctx, req) -> HttpResponse.of("OK"))
+                                         .build();
+        dummyServer.start().join();
+
+        final Server failingServer = Server.builder().port(dummyServer.activePort())
+                                           .service("/", (ctx, req) -> HttpResponse.of("OK"))
+                                           .build();
+
+        // Make sure that `failingServer` is unable to start because of the port collision.
+        assertThatThrownBy(() -> failingServer.start().join())
+                .isInstanceOf(CompletionException.class)
+                .hasCauseInstanceOf(IOException.class)
+                .hasMessageContaining("Address already in use");
+
+        final SmartLifecycle lifecycle =
+                new RetryableArmeriaServerGracefulShutdownLifecycle(failingServer, 100);
+        final AtomicBoolean success = new AtomicBoolean();
+
+        final CountDownLatch latch = new CountDownLatch(1);
+        CommonPools.blockingTaskExecutor().execute(() -> {
+            latch.countDown();
+            lifecycle.start();
+            success.set(true);
+        });
+
+        latch.await();
+        // Wait for the retry to work
+        Thread.sleep(1000);
+        dummyServer.stop().join();
+        await().untilTrue(success);
+    }
+}