feat(s3): add expectContinueEnabled to S3Configuration (#6774)

joviegas · web-flow · commit 536eb462dffb · 2026-03-12T22:09:45.000Z
* feat(s3): add disableExpect100ContinueForPuts to S3Configuration

* changed disableExpect100ContinueForPuts to expectContinueEnabled after api surface review discussions

* fixed  sonarquebe issue
diff --git a/.changes/next-release/feature-AmazonS3-7a01820.json b/.changes/next-release/feature-AmazonS3-7a01820.json
@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "Amazon S3",
+    "contributor": "",
+    "description": "Added `expectContinueEnabled` to `S3Configuration` to control the `Expect: 100-continue` header on PutObject and UploadPart requests. When set to `false`, the SDK stops adding the header. For Apache HTTP client users, to have `ApacheHttpClient.builder().expectContinueEnabled()` fully control the header, set `expectContinueEnabled(false)` on `S3Configuration`."
+}
diff --git a/services/s3/src/main/java/software/amazon/awssdk/services/s3/S3Configuration.java b/services/s3/src/main/java/software/amazon/awssdk/services/s3/S3Configuration.java
@@ -35,6 +35,7 @@
 import software.amazon.awssdk.services.s3.model.GetObjectRequest;
 import software.amazon.awssdk.services.s3.model.PutBucketAccelerateConfigurationRequest;
 import software.amazon.awssdk.services.s3.model.PutObjectRequest;
+import software.amazon.awssdk.services.s3.model.UploadPartRequest;
 import software.amazon.awssdk.services.s3.presigner.S3Presigner;
 import software.amazon.awssdk.utils.builder.CopyableBuilder;
 import software.amazon.awssdk.utils.builder.ToCopyableBuilder;
@@ -70,11 +71,18 @@ public final class S3Configuration implements ServiceConfiguration, ToCopyableBu
      */
     private static final boolean DEFAULT_CHUNKED_ENCODING_ENABLED = true;
 
+    /**
+     * By default, the SDK sends the {@code Expect: 100-continue} header for {@link PutObjectRequest}
+     * and {@link UploadPartRequest}.
+     */
+    private static final boolean DEFAULT_EXPECT_CONTINUE_ENABLED = true;
+
     private final FieldWithDefault<Boolean> pathStyleAccessEnabled;
     private final FieldWithDefault<Boolean> accelerateModeEnabled;
     private final FieldWithDefault<Boolean> dualstackEnabled;
     private final FieldWithDefault<Boolean> checksumValidationEnabled;
     private final FieldWithDefault<Boolean> chunkedEncodingEnabled;
+    private final FieldWithDefault<Boolean> expectContinueEnabled;
     private final Boolean useArnRegionEnabled;
     private final Boolean multiRegionEnabled;
     private final FieldWithDefault<Supplier<ProfileFile>> profileFile;
@@ -87,6 +95,8 @@ private S3Configuration(DefaultS3ServiceConfigurationBuilder builder) {
         this.checksumValidationEnabled = FieldWithDefault.create(builder.checksumValidationEnabled,
                                                                  DEFAULT_CHECKSUM_VALIDATION_ENABLED);
         this.chunkedEncodingEnabled = FieldWithDefault.create(builder.chunkedEncodingEnabled, DEFAULT_CHUNKED_ENCODING_ENABLED);
+        this.expectContinueEnabled = FieldWithDefault.create(builder.expectContinueEnabled,
+                                                             DEFAULT_EXPECT_CONTINUE_ENABLED);
         this.profileFile = FieldWithDefault.create(builder.profileFile, ProfileFile::defaultProfileFile);
         this.profileName = FieldWithDefault.create(builder.profileName,
                                                    ProfileFileSystemSetting.AWS_PROFILE.getStringValueOrThrow());
@@ -216,6 +226,26 @@ public boolean chunkedEncodingEnabled() {
         return chunkedEncodingEnabled.value();
     }
 
+    /**
+     * Returns whether the S3 SDK client's explicit setting of the {@code Expect: 100-continue} header is enabled for
+     * {@link PutObjectRequest} and {@link UploadPartRequest}. This controls whether the SDK adds the header during
+     * request interceptor processing.
+     * <p>
+     * By default, the SDK sends the {@code Expect: 100-continue} header for these operations, allowing the server to
+     * reject the request before the client sends the full payload. Setting this to {@code false} disables this behavior.
+     * <p>
+     * <b>Note:</b> When using the Apache HTTP client, the Apache client also independently adds the
+     * {@code Expect: 100-continue} header by default via its own {@code expectContinueEnabled} setting. To fully
+     * suppress the header on the wire, you must also disable it on the Apache HTTP client builder using
+     * {@code ApacheHttpClient.builder().expectContinueEnabled(false)}.
+     *
+     * @return True if the Expect: 100-continue header is enabled.
+     * @see S3Configuration.Builder#expectContinueEnabled(Boolean)
+     */
+    public boolean expectContinueEnabled() {
+        return expectContinueEnabled.value();
+    }
+
     /**
      * Returns whether the client is allowed to make cross-region calls when an S3 Access Point ARN has a different
      * region to the one configured on the client.
@@ -246,6 +276,7 @@ public Builder toBuilder() {
                 .pathStyleAccessEnabled(pathStyleAccessEnabled.valueOrNullIfDefault())
                 .checksumValidationEnabled(checksumValidationEnabled.valueOrNullIfDefault())
                 .chunkedEncodingEnabled(chunkedEncodingEnabled.valueOrNullIfDefault())
+                .expectContinueEnabled(expectContinueEnabled.valueOrNullIfDefault())
                 .useArnRegionEnabled(useArnRegionEnabled)
                 .profileFile(profileFile.valueOrNullIfDefault())
                 .profileName(profileName.valueOrNullIfDefault());
@@ -355,6 +386,26 @@ public interface Builder extends CopyableBuilder<Builder, S3Configuration> {
          */
         Builder chunkedEncodingEnabled(Boolean chunkedEncodingEnabled);
 
+        Boolean expectContinueEnabled();
+
+        /**
+         * Option to enable or disable the S3 SDK client's explicit setting of the {@code Expect: 100-continue} header
+         * for {@link PutObjectRequest} and {@link UploadPartRequest}.
+         * <p>
+         * By default, the SDK sends the {@code Expect: 100-continue} header for these operations, allowing the server to
+         * reject the request before the client sends the full payload. Setting this to {@code false} disables this behavior.
+         * <p>
+         * <b>Note:</b> When using the Apache HTTP client, the Apache client also independently adds the
+         * {@code Expect: 100-continue} header by default via its own {@code expectContinueEnabled} setting. To fully
+         * suppress the header on the wire, you must also disable it on the Apache HTTP client builder using
+         * {@code ApacheHttpClient.builder().expectContinueEnabled(false)}.
+         * <p>
+         * Enabled by default (i.e., the header is sent).
+         *
+         * @see S3Configuration#expectContinueEnabled()
+         */
+        Builder expectContinueEnabled(Boolean expectContinueEnabled);
+
         Boolean useArnRegionEnabled();
 
         /**
@@ -423,6 +474,7 @@ static final class DefaultS3ServiceConfigurationBuilder implements Builder {
         private Boolean pathStyleAccessEnabled;
         private Boolean checksumValidationEnabled;
         private Boolean chunkedEncodingEnabled;
+        private Boolean expectContinueEnabled;
         private Boolean useArnRegionEnabled;
         private Boolean multiRegionEnabled;
         private Supplier<ProfileFile> profileFile;
@@ -500,14 +552,29 @@ public Builder chunkedEncodingEnabled(Boolean chunkedEncodingEnabled) {
         }
 
         @Override
-        public Boolean useArnRegionEnabled() {
-            return useArnRegionEnabled;
+        public Boolean expectContinueEnabled() {
+            return expectContinueEnabled;
         }
 
         public void setChunkedEncodingEnabled(Boolean chunkedEncodingEnabled) {
             chunkedEncodingEnabled(chunkedEncodingEnabled);
         }
 
+        @Override
+        public Builder expectContinueEnabled(Boolean expectContinueEnabled) {
+            this.expectContinueEnabled = expectContinueEnabled;
+            return this;
+        }
+
+        public void setExpectContinueEnabled(Boolean expectContinueEnabled) {
+            expectContinueEnabled(expectContinueEnabled);
+        }
+
+        @Override
+        public Boolean useArnRegionEnabled() {
+            return useArnRegionEnabled;
+        }
+
         @Override
         public Builder useArnRegionEnabled(Boolean useArnRegionEnabled) {
             this.useArnRegionEnabled = useArnRegionEnabled;
diff --git a/services/s3/src/main/java/software/amazon/awssdk/services/s3/internal/handlers/StreamingRequestInterceptor.java b/services/s3/src/main/java/software/amazon/awssdk/services/s3/internal/handlers/StreamingRequestInterceptor.java
@@ -17,15 +17,19 @@
 
 import java.util.Optional;
 import software.amazon.awssdk.annotations.SdkInternalApi;
+import software.amazon.awssdk.core.ServiceConfiguration;
 import software.amazon.awssdk.core.interceptor.Context;
 import software.amazon.awssdk.core.interceptor.ExecutionAttributes;
 import software.amazon.awssdk.core.interceptor.ExecutionInterceptor;
+import software.amazon.awssdk.core.interceptor.SdkExecutionAttribute;
 import software.amazon.awssdk.http.SdkHttpRequest;
+import software.amazon.awssdk.services.s3.S3Configuration;
 import software.amazon.awssdk.services.s3.model.PutObjectRequest;
 import software.amazon.awssdk.services.s3.model.UploadPartRequest;
 
 /**
- * Interceptor to add an 'Expect: 100-continue' header to the HTTP Request if it represents a PUT Object request.
+ * Interceptor to add an 'Expect: 100-continue' header to the HTTP Request if it represents a PUT Object or Upload Part
+ * request. This behavior can be disabled via {@link S3Configuration#expectContinueEnabled()}.
  */
 @SdkInternalApi
 //TODO: This should be generalized for all streaming requests
@@ -37,24 +41,38 @@ public final class StreamingRequestInterceptor implements ExecutionInterceptor {
     @Override
     public SdkHttpRequest modifyHttpRequest(Context.ModifyHttpRequest context,
                                             ExecutionAttributes executionAttributes) {
-        if (shouldAddExpectContinueHeader(context)) {
+        if (shouldAddExpectContinueHeader(context, executionAttributes)) {
             return context.httpRequest().toBuilder().putHeader("Expect", "100-continue").build();
         }
         return context.httpRequest();
     }
 
-    private boolean shouldAddExpectContinueHeader(Context.ModifyHttpRequest context) {
+    private boolean shouldAddExpectContinueHeader(Context.ModifyHttpRequest context,
+                                                  ExecutionAttributes executionAttributes) {
         // Only applies to streaming operations
         if (!(context.request() instanceof PutObjectRequest
               || context.request() instanceof UploadPartRequest)) {
             return false;
         }
+
+        if (isExpect100ContinueDisabled(executionAttributes)) {
+            return false;
+        }
+
         return getContentLengthHeader(context.httpRequest())
             .map(Long::parseLong)
             .map(length -> length != 0L)
             .orElse(true);
     }
 
+    private boolean isExpect100ContinueDisabled(ExecutionAttributes executionAttributes) {
+        ServiceConfiguration serviceConfig = executionAttributes.getAttribute(SdkExecutionAttribute.SERVICE_CONFIG);
+        if (serviceConfig instanceof S3Configuration) {
+            return !((S3Configuration) serviceConfig).expectContinueEnabled();
+        }
+        return false;
+    }
+
     /**
      * Retrieves content length header value.
      * Checks x-amz-decoded-content-length first, then falls back to Content-Length.
diff --git a/services/s3/src/test/java/software/amazon/awssdk/services/s3/S3ConfigurationTest.java b/services/s3/src/test/java/software/amazon/awssdk/services/s3/S3ConfigurationTest.java
@@ -39,13 +39,14 @@ public void clearSystemProperty() {
     @Test
     public void createConfiguration_minimal() {
         S3Configuration config = S3Configuration.builder().build();
-        assertThat(config.accelerateModeEnabled()).isEqualTo(false);
-        assertThat(config.checksumValidationEnabled()).isEqualTo(true);
-        assertThat(config.chunkedEncodingEnabled()).isEqualTo(true);
-        assertThat(config.dualstackEnabled()).isEqualTo(false);
-        assertThat(config.multiRegionEnabled()).isEqualTo(true);
-        assertThat(config.pathStyleAccessEnabled()).isEqualTo(false);
-        assertThat(config.useArnRegionEnabled()).isEqualTo(false);
+        assertThat(config.accelerateModeEnabled()).isFalse();
+        assertThat(config.checksumValidationEnabled()).isTrue();
+        assertThat(config.chunkedEncodingEnabled()).isTrue();
+        assertThat(config.dualstackEnabled()).isFalse();
+        assertThat(config.multiRegionEnabled()).isTrue();
+        assertThat(config.pathStyleAccessEnabled()).isFalse();
+        assertThat(config.useArnRegionEnabled()).isFalse();
+        assertThat(config.expectContinueEnabled()).isTrue();
     }
 
     @Test
diff --git a/services/s3/src/test/java/software/amazon/awssdk/services/s3/functionaltests/Expect100ContinueHeaderTest.java b/services/s3/src/test/java/software/amazon/awssdk/services/s3/functionaltests/Expect100ContinueHeaderTest.java
diff --git a/services/s3/src/test/java/software/amazon/awssdk/services/s3/internal/handlers/StreamingRequestInterceptorTest.java b/services/s3/src/test/java/software/amazon/awssdk/services/s3/internal/handlers/StreamingRequestInterceptorTest.java
