Append user agent for retry mode

.changes/next-release/feature-AWSSDKforJavav2-5b5a872.json

@@ -0,0 +1,6 @@
+{
+    "category": "AWS SDK for Java v2", 
+    "contributor": "", 
+    "type": "feature", 
+    "description": "Include the retry mode STANDARD or LEGACY in the user agents list."
+}

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/http/pipeline/stages/ApplyUserAgentStage.java

@@ -42,6 +42,8 @@ public class ApplyUserAgentStage implements MutableRequestToRequestPipeline {
 
     private static final String IO = "io";
     private static final String HTTP = "http";
+    private static final String CONFIG = "cfg";
+    private static final String RETRY_MODE = "retry-mode";
 
     private static final String AWS_EXECUTION_ENV_PREFIX = "exec-env/";
 
@@ -94,6 +96,15 @@ private StringBuilder getUserAgent(SdkClientConfiguration config, List<ApiName>
                  .append("/")
                  .append(SdkHttpUtils.urlEncode(clientName));
 
+        String retryMode = config.option(SdkClientOption.RETRY_POLICY).retryMode().toString();
+
+        userAgent.append(SPACE)
+                 .append(CONFIG)
+                 .append("/")
+                 .append(RETRY_MODE)
+                 .append("/")
+                 .append(StringUtils.lowerCase(retryMode));
+
         if (!requestApiNames.isEmpty()) {
             String requestUserAgent = requestApiNames.stream()
                     .map(n -> n.name() + "/" + n.version())

core/sdk-core/src/main/java/software/amazon/awssdk/core/retry/RetryPolicy.java

@@ -25,6 +25,7 @@
 import software.amazon.awssdk.core.retry.conditions.RetryCondition;
 import software.amazon.awssdk.core.retry.conditions.TokenBucketRetryCondition;
 import software.amazon.awssdk.utils.ToString;
+import software.amazon.awssdk.utils.Validate;
 import software.amazon.awssdk.utils.builder.CopyableBuilder;
 import software.amazon.awssdk.utils.builder.ToCopyableBuilder;
 
@@ -103,6 +104,9 @@ public static Builder builder() {
      * Create a {@link RetryPolicy.Builder} populated with the defaults from the provided {@link RetryMode}.
      */
     public static Builder builder(RetryMode retryMode) {
+        Validate.paramNotNull(retryMode, "The retry mode cannot be set as null. If you don't want to set the retry mode,"
+                                    + " please use the other builder method without setting retry mode, and the default retry"
+                                    + " mode will be used.");
         return new BuilderImpl(retryMode);
     }
 

core/sdk-core/src/test/java/software/amazon/awssdk/core/http/AmazonHttpClientTest.java

@@ -43,6 +43,8 @@
 import software.amazon.awssdk.core.exception.SdkClientException;
 import software.amazon.awssdk.core.internal.http.AmazonSyncHttpClient;
 import software.amazon.awssdk.core.internal.http.timers.ClientExecutionAndRequestTimerTestUtils;
+import software.amazon.awssdk.core.retry.RetryMode;
+import software.amazon.awssdk.core.retry.RetryPolicy;
 import software.amazon.awssdk.http.ExecutableHttpRequest;
 import software.amazon.awssdk.http.HttpExecuteRequest;
 import software.amazon.awssdk.http.HttpExecuteResponse;
@@ -183,6 +185,33 @@ public void testUserAgentContainsHttpClientInfo() {
         Assert.assertTrue(userAgent.contains("http/UNKNOWN"));
     }
 
+    @Test
+    public void testUserAgentContainsRetryModeInfo() {
+        HttpResponseHandler<?> handler = mock(HttpResponseHandler.class);
+
+        SdkClientConfiguration config = HttpTestUtils.testClientConfiguration().toBuilder()
+                                                     .option(SdkClientOption.SYNC_HTTP_CLIENT, sdkHttpClient)
+                                                     .option(SdkClientOption.CLIENT_TYPE, ClientType.SYNC)
+                                                     .option(SdkClientOption.ENDPOINT, URI.create("http://example.com"))
+                                                     .option(SdkClientOption.RETRY_POLICY, RetryPolicy.forRetryMode(RetryMode.STANDARD))
+                                                     .build();
+        AmazonSyncHttpClient client = new AmazonSyncHttpClient(config);
+
+        client.requestExecutionBuilder()
+              .request(ValidSdkObjects.sdkHttpFullRequest().build())
+              .originalRequest(NoopTestRequest.builder().build())
+              .executionContext(ClientExecutionAndRequestTimerTestUtils.executionContext(null))
+              .execute(combinedSyncResponseHandler(handler, null));
+
+        ArgumentCaptor<HttpExecuteRequest> httpRequestCaptor = ArgumentCaptor.forClass(HttpExecuteRequest.class);
+        verify(sdkHttpClient).prepareRequest(httpRequestCaptor.capture());
+
+        final String userAgent = httpRequestCaptor.getValue().httpRequest().firstMatchingHeader("User-Agent")
+                                                  .orElseThrow(() -> new AssertionError("User-Agent header was not found"));
+
+        Assert.assertTrue(userAgent.contains("cfg/retry-mode/standard"));
+    }
+
     @Test
     public void closeClient_shouldCloseDependencies() {
         SdkClientConfiguration config = HttpTestUtils.testClientConfiguration()

core/sdk-core/src/test/java/software/amazon/awssdk/core/retry/RetryPolicyTest.java

@@ -16,6 +16,7 @@
 package software.amazon.awssdk.core.retry;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.Mockito.verify;
 
 import org.junit.Assert;
@@ -82,6 +83,19 @@ public void nonRetryPolicy_shouldUseNullCondition() {
         assertThat(noneRetry.throttlingBackoffStrategy()).isEqualTo(BackoffStrategy.none());
     }
 
+    @Test
+    public void nonRetryMode_shouldUseDefaultRetryMode() {
+        RetryPolicy policy = RetryPolicy.builder().build();
+        assertThat(policy.retryMode().toString()).isEqualTo("LEGACY");
+    }
+
+    @Test
+    public void nullRetryMode_shouldThrowNullPointerException() {
+        assertThatThrownBy(() -> RetryPolicy.builder(null).build())
+            .isInstanceOf(NullPointerException.class)
+            .hasMessageContaining("retry mode cannot be set as null");
+    }
+
     @Test
     public void maxRetriesFromRetryModeIsCorrect() {
         assertThat(RetryPolicy.forRetryMode(RetryMode.LEGACY).numRetries()).isEqualTo(3);