[DataPipe] Small doc improvement for S3

ghstack-source-id: 3892ecb9a7da3e8b7833347dafae3defcfd09366
Pull Request resolved: #784

torchdata/datapipes/iter/load/README.md

@@ -42,13 +42,16 @@ Please refer to the documentation:
 
 ### Note
 
+Your environment must be properly configured for AWS to use the DataPipes. It is possible to do that via the AWS Command
+Line Interface (`aws configure`).
+
 It's recommended to set up a detailed configuration file with the `AWS_CONFIG_FILE` environment variable. The following
 environment variables are also parsed: `HOME`, `S3_USE_HTTPS`, `S3_VERIFY_SSL`, `S3_ENDPOINT_URL`, `AWS_REGION` (would
 be overwritten by the `region` variable).
 
 ### Troubleshooting
 
-If you get `Access Denied`, it's very possibly a
+If you get `Access Denied` or no response, it's very possibly a
 [wrong region configuration](https://github.com/aws/aws-sdk-cpp/issues/1211) or an
 [accessing issue with `aws-sdk-cpp`](https://aws.amazon.com/premiumsupport/knowledge-center/s3-access-denied-aws-sdk/).
 

torchdata/datapipes/iter/load/s3io.py

@@ -25,6 +25,11 @@ class S3FileListerIterDataPipe(IterDataPipe[str]):
            until all files are iterated.
         3. ``request_timeout_ms`` and ``region`` will overwrite settings in the configuration file or
            environment variables.
+        4. The lack of AWS proper configuration can lead empty response. For more details related to S3 IO DataPipe
+           setup and AWS config, please see the `README file`_.
+
+    .. _README file:
+        https://github.com/pytorch/data/tree/main/torchdata/datapipes/iter/load#s3-io-datapipe-documentation
 
     Args:
         source_datapipe: a DataPipe that contains URLs/URL prefixes to s3 files
@@ -77,6 +82,11 @@ class S3FileLoaderIterDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
         1. ``source_datapipe`` **must** contain a list of valid S3 URLs.
         2. ``request_timeout_ms`` and ``region`` will overwrite settings in the
            configuration file or environment variables.
+        3. The lack of AWS proper configuration can lead empty response. For more details related to S3 IO DataPipe
+           setup and AWS config, please see the `README file`_.
+
+    .. _README file:
+        https://github.com/pytorch/data/tree/main/torchdata/datapipes/iter/load#s3-io-datapipe-documentation
 
     Args:
         source_datapipe: a DataPipe that contains URLs to s3 files