Add logs on docker build failure

samcli/lib/build/app_builder.py

@@ -430,6 +430,7 @@ def _build_lambda_image(self, function_name: str, metadata: Dict, architecture:
             LOG.debug("%s image is built for %s function", build_image, function_name)
         except docker.errors.BuildError as ex:
             LOG.error("Failed building function %s", function_name)
+            self._stream_lambda_image_build_logs(ex.build_log, function_name, False)
             raise DockerBuildFailed(str(ex)) from ex
 
         # The Docker-py low level api will stream logs back but if an exception is raised by the api
@@ -445,7 +446,9 @@ def _build_lambda_image(self, function_name: str, metadata: Dict, architecture:
 
         return docker_tag
 
-    def _stream_lambda_image_build_logs(self, build_logs: List[Dict[str, str]], function_name: str) -> None:
+    def _stream_lambda_image_build_logs(
+        self, build_logs: List[Dict[str, str]], function_name: str, throw_on_error: bool = True
+    ) -> None:
         """
         Stream logs to the console from an Lambda image build.
 
@@ -456,7 +459,7 @@ def _stream_lambda_image_build_logs(self, build_logs: List[Dict[str, str]], func
         function_name str
             Name of the function that is being built
         """
-        build_log_streamer = LogStreamer(self._stream_writer)
+        build_log_streamer = LogStreamer(self._stream_writer, throw_on_error)
         try:
             build_log_streamer.stream_progress(build_logs)
         except LogStreamError as ex:

samcli/lib/docker/log_streamer.py

@@ -22,12 +22,13 @@ def __init__(self, msg: str) -> None:
 
 
 class LogStreamer:
-    def __init__(self, stream: StreamWriter):
+    def __init__(self, stream: StreamWriter, throw_on_error: bool = True):
         self._stream = stream
         self._cursor_up_formatter = CursorUpFormatter()
         self._cursor_down_formatter = CursorDownFormatter()
         self._cursor_left_formatter = CursorLeftFormatter()
         self._cursor_clear_formatter = ClearLineFormatter()
+        self._throw_on_error = throw_on_error
 
     def stream_progress(self, logs: docker.APIClient.logs):
         """
@@ -73,7 +74,12 @@ def _stream_write(self, _id: str, status: str, stream: str, progress: str, error
         :param error: docker log error
         """
         if error:
-            raise LogStreamError(msg=error)
+            if self._throw_on_error:
+                raise LogStreamError(msg=error)
+            else:
+                self._stream.write_str(error)
+                return
+
         if not status and not stream:
             return
 

tests/unit/lib/build_module/test_app_builder.py

@@ -1728,13 +1728,26 @@ def test_can_build_image_function_under_debug_with_target(self, mock_os):
             ),
         )
 
+    def test_can_raise_missing_dockerfile_error(self):
+        with self.assertRaises(DockerBuildFailed) as ex:
+            self.builder._build_lambda_image("Name", {}, X86_64)
+
+        self.assertEqual(ex.exception.args, ("Docker file or Docker context metadata are missed.",))
+
     def test_can_raise_build_error(self):
         self.docker_client_mock.images.build.side_effect = docker.errors.BuildError(
-            reason="Missing Dockerfile", build_log="Build failed"
+            reason="Build failure", build_log=[{"stream": "Some earlier log"}, {"error": "Build failed"}]
         )
 
-        with self.assertRaises(DockerBuildFailed):
-            self.builder._build_lambda_image("Name", {}, X86_64)
+        with self.assertRaises(DockerBuildFailed) as ex:
+            self.builder._build_lambda_image("Name", {"Dockerfile": "Dockerfile", "DockerContext": "context"}, X86_64)
+
+        self.assertEqual(ex.exception.args, ("Build failure",))
+        self.assertEqual(self.stream_mock.write_str.call_count, 4, self.stream_mock.write_str.call_args_list)
+        self.assertEqual(
+            self.stream_mock.write_str.call_args_list,
+            [call("Some earlier log"), call(""), call("Build failed"), call(os.linesep)],
+        )
 
 
 class TestApplicationBuilder_load_lambda_image_function(TestCase):