Scoped the default S3 endpoint to region of the client

Signed-off-by: Raghuvansh Raj <raghraaj@amazon.com>

Author: raghuvanshraj

plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/S3AsyncService.java

@@ -60,7 +60,7 @@ class S3AsyncService implements Closeable {
 
     private static final String STS_ENDPOINT_OVERRIDE_SYSTEM_PROPERTY = "aws.stsEndpointOverride";
 
-    private static final String DEFAULT_S3_ENDPOINT = "s3.amazonaws.com";
+    private static final String GLOBAL_S3_ENDPOINT = "s3.amazonaws.com";
 
     private volatile Map<S3ClientSettings, AmazonAsyncS3Reference> clientsCache = emptyMap();
 
@@ -174,7 +174,11 @@ synchronized AmazonAsyncS3WithCredentials buildClient(
         final AwsCredentialsProvider credentials = buildCredentials(logger, clientSettings);
         builder.credentialsProvider(credentials);
 
-        String endpoint = Strings.hasLength(clientSettings.endpoint) ? clientSettings.endpoint : DEFAULT_S3_ENDPOINT;
+        String s3Endpoint = Strings.hasText(clientSettings.region)
+            ? "s3." + Region.of(clientSettings.region).toString() + ".amazonaws.com"
+            : GLOBAL_S3_ENDPOINT;
+
+        String endpoint = Strings.hasLength(clientSettings.endpoint) ? clientSettings.endpoint : s3Endpoint;
         if ((endpoint.startsWith("http://") || endpoint.startsWith("https://")) == false) {
             // Manually add the schema to the endpoint to work around https://github.com/aws/aws-sdk-java/issues/2274
             endpoint = clientSettings.protocol.toString() + "://" + endpoint;

plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/S3Service.java

@@ -98,7 +98,7 @@ class S3Service implements Closeable {
 
     private static final String STS_ENDPOINT_OVERRIDE_SYSTEM_PROPERTY = "aws.stsEndpointOverride";
 
-    private static final String DEFAULT_S3_ENDPOINT = "s3.amazonaws.com";
+    private static final String GLOBAL_S3_ENDPOINT = "s3.amazonaws.com";
 
     private volatile Map<S3ClientSettings, AmazonS3Reference> clientsCache = emptyMap();
 
@@ -204,7 +204,11 @@ AmazonS3WithCredentials buildClient(final S3ClientSettings clientSettings) {
         builder.httpClientBuilder(buildHttpClient(clientSettings));
         builder.overrideConfiguration(buildOverrideConfiguration(clientSettings));
 
-        String endpoint = Strings.hasLength(clientSettings.endpoint) ? clientSettings.endpoint : DEFAULT_S3_ENDPOINT;
+        String s3Endpoint = Strings.hasText(clientSettings.region)
+            ? "s3." + Region.of(clientSettings.region).toString() + ".amazonaws.com"
+            : GLOBAL_S3_ENDPOINT;
+
+        String endpoint = Strings.hasLength(clientSettings.endpoint) ? clientSettings.endpoint : s3Endpoint;
         if ((endpoint.startsWith("http://") || endpoint.startsWith("https://")) == false) {
             // Manually add the schema to the endpoint to work around https://github.com/aws/aws-sdk-java/issues/2274
             // TODO: Remove this once fixed in the AWS SDK