Add support for stdin/stdout streams for CRT client

This also included:

* Refactoring the s3transfer crt layer to better organize
  the branching introduced in supporting both file objects
  and file name.
* Introduce additional helper test methods to reduce verbosity
  of s3transfer crt test and improve reusability.

Author: kyleknap

.changes/next-release/enhancement-s3cp-40300.json

@@ -0,0 +1,5 @@
+{
+  "type": "enhancement",
+  "category": "``s3 cp``",
+  "description": "Support streaming uploads from stdin and streaming downloads to stdout for CRT transfer client"
+}

awscli/customizations/s3/factory.py

@@ -70,8 +70,6 @@ def create_transfer_manager(self, params, runtime_config,
     def _compute_transfer_client_type(self, params, runtime_config):
         if params.get('paths_type') == 's3s3':
             return constants.DEFAULT_TRANSFER_CLIENT
-        if params.get('is_stream'):
-            return constants.DEFAULT_TRANSFER_CLIENT
         return runtime_config.get(
             'preferred_transfer_client', constants.DEFAULT_TRANSFER_CLIENT)
 

awscli/s3transfer/crt.py

@@ -428,19 +428,12 @@ def _crt_request_from_aws_request(self, aws_request):
                 headers_list.append((name, str(value, 'utf-8')))
 
         crt_headers = awscrt.http.HttpHeaders(headers_list)
-        # CRT requires body (if it exists) to be an I/O stream.
-        crt_body_stream = None
-        if aws_request.body:
-            if hasattr(aws_request.body, 'seek'):
-                crt_body_stream = aws_request.body
-            else:
-                crt_body_stream = BytesIO(aws_request.body)
 
         crt_request = awscrt.http.HttpRequest(
             method=aws_request.method,
             path=crt_path,
             headers=crt_headers,
-            body_stream=crt_body_stream,
+            body_stream=aws_request.body,
         )
         return crt_request
 
@@ -453,6 +446,25 @@ def _convert_to_crt_http_request(self, botocore_http_request):
             crt_request.headers.set("host", url_parts.netloc)
         if crt_request.headers.get('Content-MD5') is not None:
             crt_request.headers.remove("Content-MD5")
+
+        # In general, the CRT S3 client expects a content length header. It
+        # only expects a missing content length header if the body is not
+        # seekable. However, botocore does not set the content length header
+        # for GetObject API requests and so we set the content length to zero
+        # to meet the CRT S3 client's expectation that the content length
+        # header is set even if there is no body.
+        if crt_request.headers.get('Content-Length') is None:
+            if botocore_http_request.body is None:
+                crt_request.headers.add('Content-Length', "0")
+
+        # Botocore sets the Transfer-Encoding header when it cannot determine
+        # the content length of the request body (e.g. it's not seekable).
+        # However, CRT does not support this header, but it supports
+        # non-seekable bodies. So we remove this header to not cause issues
+        # in the downstream CRT S3 request.
+        if crt_request.headers.get('Transfer-Encoding') is not None:
+            crt_request.headers.remove('Transfer-Encoding')
+
         return crt_request
 
     def _capture_http_request(self, request, **kwargs):
@@ -555,39 +567,19 @@ def __init__(self, crt_request_serializer, os_utils):
     def get_make_request_args(
         self, request_type, call_args, coordinator, future, on_done_after_calls
     ):
-        recv_filepath = None
-        send_filepath = None
-        s3_meta_request_type = getattr(
-            S3RequestType, request_type.upper(), S3RequestType.DEFAULT
-        )
-        on_done_before_calls = []
-        if s3_meta_request_type == S3RequestType.GET_OBJECT:
-            final_filepath = call_args.fileobj
-            recv_filepath = self._os_utils.get_temp_filename(final_filepath)
-            file_ondone_call = RenameTempFileHandler(
-                coordinator, final_filepath, recv_filepath, self._os_utils
-            )
-            on_done_before_calls.append(file_ondone_call)
-        elif s3_meta_request_type == S3RequestType.PUT_OBJECT:
-            send_filepath = call_args.fileobj
-            data_len = self._os_utils.get_file_size(send_filepath)
-            call_args.extra_args["ContentLength"] = data_len
-
-        crt_request = self._request_serializer.serialize_http_request(
-            request_type, future
+        return getattr(
+            self,
+            f'_get_make_request_args_{request_type}',
+            self._default_get_make_request_args,
+        )(
+            request_type=request_type,
+            call_args=call_args,
+            coordinator=coordinator,
+            future=future,
+            on_done_before_calls=[],
+            on_done_after_calls=on_done_after_calls,
         )
 
-        return {
-            'request': crt_request,
-            'type': s3_meta_request_type,
-            'recv_filepath': recv_filepath,
-            'send_filepath': send_filepath,
-            'on_done': self.get_crt_callback(
-                future, 'done', on_done_before_calls, on_done_after_calls
-            ),
-            'on_progress': self.get_crt_callback(future, 'progress'),
-        }
-
     def get_crt_callback(
         self,
         future,
@@ -613,6 +605,96 @@ def invoke_all_callbacks(*args, **kwargs):
 
         return invoke_all_callbacks
 
+    def _get_make_request_args_put_object(
+        self,
+        request_type,
+        call_args,
+        coordinator,
+        future,
+        on_done_before_calls,
+        on_done_after_calls,
+    ):
+        send_filepath = None
+        if isinstance(call_args.fileobj, str):
+            send_filepath = call_args.fileobj
+            data_len = self._os_utils.get_file_size(send_filepath)
+            call_args.extra_args["ContentLength"] = data_len
+        else:
+            call_args.extra_args["Body"] = call_args.fileobj
+
+        # Suppress botocore's automatic MD5 calculation by setting an override
+        # value that will get deleted in the BotocoreCRTRequestSerializer.
+        # The CRT S3 client will automatically compute checksums as part of
+        # requests it makes.
+        call_args.extra_args["ContentMD5"] = "override-to-be-removed"
+
+        make_request_args = self._default_get_make_request_args(
+            request_type=request_type,
+            call_args=call_args,
+            coordinator=coordinator,
+            future=future,
+            on_done_before_calls=on_done_before_calls,
+            on_done_after_calls=on_done_after_calls,
+        )
+        make_request_args['send_filepath'] = send_filepath
+        return make_request_args
+
+    def _get_make_request_args_get_object(
+        self,
+        request_type,
+        call_args,
+        coordinator,
+        future,
+        on_done_before_calls,
+        on_done_after_calls,
+    ):
+        recv_filepath = None
+        on_body = None
+        if isinstance(call_args.fileobj, str):
+            final_filepath = call_args.fileobj
+            recv_filepath = self._os_utils.get_temp_filename(final_filepath)
+            on_done_before_calls.append(
+                RenameTempFileHandler(
+                    coordinator, final_filepath, recv_filepath, self._os_utils
+                )
+            )
+        else:
+            on_body = OnBodyFileObjWriter(call_args.fileobj)
+
+        make_request_args = self._default_get_make_request_args(
+            request_type=request_type,
+            call_args=call_args,
+            coordinator=coordinator,
+            future=future,
+            on_done_before_calls=on_done_before_calls,
+            on_done_after_calls=on_done_after_calls,
+        )
+        make_request_args['recv_filepath'] = recv_filepath
+        make_request_args['on_body'] = on_body
+        return make_request_args
+
+    def _default_get_make_request_args(
+        self,
+        request_type,
+        call_args,
+        coordinator,
+        future,
+        on_done_before_calls,
+        on_done_after_calls,
+    ):
+        return {
+            'request': self._request_serializer.serialize_http_request(
+                request_type, future
+            ),
+            'type': getattr(
+                S3RequestType, request_type.upper(), S3RequestType.DEFAULT
+            ),
+            'on_done': self.get_crt_callback(
+                future, 'done', on_done_before_calls, on_done_after_calls
+            ),
+            'on_progress': self.get_crt_callback(future, 'progress'),
+        }
+
 
 class RenameTempFileHandler:
     def __init__(self, coordinator, final_filename, temp_filename, osutil):
@@ -642,3 +724,11 @@ def __init__(self, coordinator):
 
     def __call__(self, **kwargs):
         self._coordinator.set_done_callbacks_complete()
+
+
+class OnBodyFileObjWriter:
+    def __init__(self, fileobj):
+        self._fileobj = fileobj
+
+    def __call__(self, chunk, **kwargs):
+        self._fileobj.write(chunk)

awscli/topics/s3-config.rst

@@ -297,9 +297,6 @@ files to and from S3. Valid choices are:
 
   * S3 to S3 copies - Falls back to using the ``default`` transfer client
 
-  * Streaming uploads from standard input and downloads to standard output -
-    Falls back to using ``default`` transfer client.
-
   * Region redirects - Transfers fail for requests sent to a region that does
     not match the region of the targeted S3 bucket.
 

tests/functional/s3/__init__.py

@@ -436,6 +436,7 @@ def setUp(self):
         self.mock_crt_client.return_value.make_request.side_effect = \
             self.simulate_make_request_side_effect
         self.files = FileCreator()
+        self.expected_download_content = b'content'
 
     def tearDown(self):
         super(BaseCRTTransferClientTest, self).tearDown()
@@ -456,6 +457,8 @@ def get_config_file_contents(self):
     def simulate_make_request_side_effect(self, *args, **kwargs):
         if kwargs.get('recv_filepath'):
             self.simulate_file_download(kwargs['recv_filepath'])
+        elif kwargs.get('on_body'):
+            self.simulate_on_body(kwargs['on_body'])
         s3_request = FakeCRTS3Request(
             future=FakeCRTFuture(kwargs.get('on_done'))
         )
@@ -465,11 +468,14 @@ def simulate_file_download(self, recv_filepath):
         parent_dir = os.path.dirname(recv_filepath)
         if not os.path.isdir(parent_dir):
             os.makedirs(parent_dir)
-        with open(recv_filepath, 'w') as f:
+        with open(recv_filepath, 'wb') as f:
             # The content is arbitrary as most functional tests are just going
             # to assert the file exists since it is the CRT writing the
             # data to the file.
-            f.write('content')
+            f.write(self.expected_download_content)
+
+    def simulate_on_body(self, on_body_callback):
+        on_body_callback(chunk=self.expected_download_content, offset=0)
 
     def get_crt_make_request_calls(self):
         return self.mock_crt_client.return_value.make_request.call_args_list
@@ -489,7 +495,8 @@ def assert_crt_make_request_call(
             self, make_request_call, expected_type, expected_host,
             expected_path, expected_http_method=None,
             expected_send_filepath=None,
-            expected_recv_startswith=None):
+            expected_recv_startswith=None,
+            expected_body_content=None):
         make_request_kwargs = make_request_call[1]
         self.assertEqual(
             make_request_kwargs['type'], expected_type)
@@ -522,6 +529,15 @@ def assert_crt_make_request_call(
                     f"start with {expected_recv_startswith}"
                 )
             )
+        if expected_body_content is not None:
+            # Note: The underlying CRT awscrt.io.InputStream does not expose
+            # a public read method so we have to reach into the private,
+            # underlying stream to determine the content. We should update
+            # to use a public interface if a public interface is ever exposed.
+            self.assertEqual(
+                make_request_kwargs['request'].body_stream._stream.read(),
+                expected_body_content
+            )
 
 
 class FakeCRTS3Request:

tests/functional/s3/test_cp_command.py

@@ -2116,25 +2116,38 @@ def test_does_not_use_crt_client_for_copies(self):
         self.assertEqual(self.get_crt_make_request_calls(), [])
         self.assert_no_remaining_botocore_responses()
 
-    def test_does_not_use_crt_client_for_streaming_upload(self):
+    def test_streaming_upload_using_crt_client(self):
         cmdline = [
             's3', 'cp', '-', 's3://bucket/key'
         ]
-        self.add_botocore_put_object_response()
         with mock.patch('sys.stdin', BufferedBytesIO(b'foo')):
             self.run_command(cmdline)
-        self.assertEqual(self.get_crt_make_request_calls(), [])
-        self.assert_no_remaining_botocore_responses()
+        crt_requests = self.get_crt_make_request_calls()
+        self.assertEqual(len(crt_requests), 1)
+        self.assert_crt_make_request_call(
+            crt_requests[0],
+            expected_type=S3RequestType.PUT_OBJECT,
+            expected_host=self.get_virtual_s3_host('bucket'),
+            expected_path='/key',
+            expected_body_content=b'foo',
+        )
 
-    def test_does_not_use_crt_client_for_streaming_download(self):
+    def test_streaming_download_using_crt_client(self):
         cmdline = [
             's3', 'cp', 's3://bucket/key', '-'
         ]
-        self.add_botocore_head_object_response()
-        self.add_botocore_get_object_response()
-        self.run_command(cmdline)
-        self.assertEqual(self.get_crt_make_request_calls(), [])
-        self.assert_no_remaining_botocore_responses()
+        result = self.run_command(cmdline)
+        crt_requests = self.get_crt_make_request_calls()
+        self.assertEqual(len(crt_requests), 1)
+        self.assert_crt_make_request_call(
+            crt_requests[0],
+            expected_type=S3RequestType.GET_OBJECT,
+            expected_host=self.get_virtual_s3_host('bucket'),
+            expected_path='/key',
+        )
+        self.assertEqual(
+            result.stdout, self.expected_download_content.decode('utf-8')
+        )
 
     def test_respects_region_parameter(self):
         filename = self.files.create_file('myfile', 'mycontent')