More info about region inference

Author: DaveCTurner

modules/repository-s3/src/main/java/org/elasticsearch/repositories/s3/S3RepositoryPlugin.java

@@ -101,7 +101,7 @@ private static Region getDefaultRegion() {
             try {
                 return DefaultAwsRegionProviderChain.builder().build().getRegion();
             } catch (Exception e) {
-                logger.debug("failed to obtain region from default provider chain", e);
+                logger.info("failed to obtain region from default provider chain", e);
                 return null;
             }
         });

modules/repository-s3/src/main/java/org/elasticsearch/repositories/s3/S3Service.java

@@ -269,6 +269,14 @@ Region getClientRegion(S3ClientSettings clientSettings) {
                     S3ClientSettings.REGION.getConcreteSettingForNamespace("CLIENT_NAME").getKey()
                 );
                 return Region.of(guessedRegion);
+            } else {
+                LOGGER.info(
+                    """
+                        found S3 client with endpoint [{}] which does not map to a known AWS region; \
+                        to suppress this message, configure the [{}] setting on this node""",
+                    clientSettings.endpoint,
+                    S3ClientSettings.REGION.getConcreteSettingForNamespace("CLIENT_NAME").getKey()
+                );
             }
         }
         final var defaultRegion = this.defaultRegion;