feat: add ability to pass docker build params in template

samcli/lib/build/app_builder.py

@@ -434,13 +434,17 @@ def _build_lambda_image(self, function_name: str, metadata: Dict, architecture:
         docker_tag = f"{image_name.lower()}:{tag}"
         docker_build_target = metadata.get("DockerBuildTarget", None)
         docker_build_args = metadata.get("DockerBuildArgs", {})
+        docker_build_extra_params = metadata.get("DockerBuildExtraParams", None)
 
         if not dockerfile or not docker_context:
             raise DockerBuildFailed("Docker file or Docker context metadata are missed.")
 
         if not isinstance(docker_build_args, dict):
             raise DockerBuildFailed("DockerBuildArgs needs to be a dictionary!")
 
+        if docker_build_extra_params is not None and not isinstance(docker_build_extra_params, list):
+            raise DockerBuildFailed("DockerBuildExtraParams needs to be a list!")
+
         docker_context_dir = pathlib.Path(self._base_dir, docker_context).resolve()
 
         if os.environ.get("SAM_BUILD_MODE") and isinstance(docker_build_args, dict):
@@ -460,6 +464,8 @@ def _build_lambda_image(self, function_name: str, metadata: Dict, architecture:
         }
         if docker_build_target:
             build_args["target"] = cast(str, docker_build_target)
+        if docker_build_extra_params:
+            build_args["extra_params"] = docker_build_extra_params
 
         try:
             if not self._image_build_client:

samcli/lib/samlib/resource_metadata_normalizer.py

@@ -25,12 +25,14 @@
 IMAGE_ASSET_PROPERTY = "Code.ImageUri"
 ASSET_DOCKERFILE_PATH_KEY = "aws:asset:dockerfile-path"
 ASSET_DOCKERFILE_BUILD_ARGS_KEY = "aws:asset:docker-build-args"
+ASSET_DOCKER_BUILD_EXTRA_PARAMS_KEY = "aws:asset:docker-build-extra-params"
 
 SAM_RESOURCE_ID_KEY = "SamResourceId"
 SAM_IS_NORMALIZED = "SamNormalized"
 SAM_METADATA_DOCKERFILE_KEY = "Dockerfile"
 SAM_METADATA_DOCKER_CONTEXT_KEY = "DockerContext"
 SAM_METADATA_DOCKER_BUILD_ARGS_KEY = "DockerBuildArgs"
+SAM_METADATA_DOCKER_BUILD_EXTRA_PARAMS_KEY = "DockerBuildExtraParams"
 
 ASSET_BUNDLED_METADATA_KEY = "aws:asset:is-bundled"
 SAM_METADATA_SKIP_BUILD_KEY = "SkipBuild"
@@ -189,6 +191,7 @@ def _extract_image_asset_metadata(metadata):
             SAM_METADATA_DOCKERFILE_KEY: str(dockerfile_path.as_posix()),
             SAM_METADATA_DOCKER_CONTEXT_KEY: str(asset_path),
             SAM_METADATA_DOCKER_BUILD_ARGS_KEY: metadata.get(ASSET_DOCKERFILE_BUILD_ARGS_KEY, {}),
+            SAM_METADATA_DOCKER_BUILD_EXTRA_PARAMS_KEY: metadata.get(ASSET_DOCKER_BUILD_EXTRA_PARAMS_KEY, None),
         }
 
     @staticmethod

samcli/local/docker/image_build_client.py

@@ -39,6 +39,7 @@ def build_image(
         platform: Optional[str] = None,
         target: Optional[str] = None,
         rm: bool = True,
+        extra_params: Optional[list[str]] = None,
     ) -> Generator[Dict[str, Any], None, None]:
         """
         Build a container image from a Dockerfile.
@@ -59,6 +60,8 @@ def build_image(
             Build target stage in multi-stage Dockerfile
         rm : bool
             Remove intermediate containers after build (default: True)
+        extra_params : list of str, optional
+            Extra CLI flags (e.g., ["--ssh", "default"]). Only supported by CLIBuildClient
 
         Yields
         ------
@@ -119,6 +122,7 @@ def build_image(
         platform: Optional[str] = None,
         target: Optional[str] = None,
         rm: bool = True,
+        extra_params: Optional[list[str]] = None,
     ) -> Generator[Dict[str, Any], None, None]:
         """Build image using docker-py SDK"""
         build_kwargs = {
@@ -135,6 +139,12 @@ def build_image(
         if target is not None:
             build_kwargs["target"] = target
 
+        if extra_params:
+            LOG.warning(
+                "DockerBuildExtraParams are not supported with the SDK build client and will be ignored. "
+                "Use --use-buildkit to enable CLI-based builds."
+            )
+
         _, build_logs = self.container_client.images.build(**build_kwargs)
         return build_logs  # type: ignore[no-any-return]
 
@@ -159,6 +169,7 @@ def build_image(
         platform: Optional[str] = None,
         target: Optional[str] = None,
         rm: bool = True,
+        extra_params: Optional[list[str]] = None,
     ) -> Generator[Dict[str, Any], None, None]:
         # Make dockerfile path relative to context if not absolute
         if not os.path.isabs(dockerfile):
@@ -187,6 +198,9 @@ def build_image(
         if rm:
             cmd.append("--rm")
 
+        if extra_params:
+            cmd.extend(extra_params)
+
         cmd.append(path)
 
         LOG.debug(f"Executing build command: {' '.join(cmd)}")

tests/unit/lib/build_module/test_app_builder.py

@@ -1774,6 +1774,24 @@ def test_build_lambda_image_raises_for_non_dict_docker_build_args(self):
         with self.assertRaises(DockerBuildFailed):
             self.builder._build_lambda_image("Name", metadata, X86_64)
 
+    def test_can_build_image_function_with_extra_params(self):
+        metadata = {
+            "Dockerfile": "Dockerfile",
+            "DockerContext": "context",
+            "DockerTag": "Tag",
+            "DockerBuildArgs": {"a": "b"},
+            "DockerBuildExtraParams": ["--ssh", "default"],
+        }
+
+        mock_build_client = Mock()
+        mock_build_client.build_image.return_value = iter([])
+        self.builder._image_build_client = mock_build_client
+
+        self.builder._build_lambda_image("Name", metadata, X86_64)
+
+        call_kwargs = mock_build_client.build_image.call_args[1]
+        self.assertEqual(call_kwargs["extra_params"], ["--ssh", "default"])
+
     def test_build_lambda_image_uses_latest_tag_when_not_specified(self):
         metadata = {
             "Dockerfile": "Dockerfile",

tests/unit/lib/samlib/test_resource_metadata_normalizer.py

@@ -80,6 +80,7 @@ def test_replace_all_resources_that_contain_metadata(self):
 
     def test_replace_all_resources_that_contain_image_metadata(self):
         docker_build_args = {"arg1": "val1", "arg2": "val2"}
+        docker_build_extra_params = ["--param1", "value1"]
         asset_path = pathlib.Path("/path", "to", "asset")
         dockerfile_path = pathlib.Path("path", "to", "Dockerfile")
         template_data = {
@@ -97,6 +98,7 @@ def test_replace_all_resources_that_contain_image_metadata(self):
                         "aws:asset:property": "Code.ImageUri",
                         "aws:asset:dockerfile-path": dockerfile_path,
                         "aws:asset:docker-build-args": docker_build_args,
+                        "aws:asset:docker-build-extra-params": docker_build_extra_params,
                     },
                 },
             }
@@ -112,6 +114,9 @@ def test_replace_all_resources_that_contain_image_metadata(self):
         expected_dockerfile_path = str(pathlib.Path("path", "to", "Dockerfile").as_posix())
         self.assertEqual(expected_dockerfile_path, template_data["Resources"]["Function1"]["Metadata"]["Dockerfile"])
         self.assertEqual(docker_build_args, template_data["Resources"]["Function1"]["Metadata"]["DockerBuildArgs"])
+        self.assertEqual(
+            docker_build_extra_params, template_data["Resources"]["Function1"]["Metadata"]["DockerBuildExtraParams"]
+        )
         self.assertEqual("Function1", template_data["Resources"]["Function1"]["Metadata"]["SamResourceId"])
 
     def test_replace_all_resources_that_contain_image_metadata_dockerfile_extensions(self):

tests/unit/local/docker/test_image_build_client.py

@@ -56,6 +56,19 @@ def test_build_image_minimal(self):
             rm=True,
         )
 
+    @patch("samcli.local.docker.image_build_client.LOG")
+    def test_build_image_extra_params_logs_warning(self, mock_log):
+        """Test that extra_params triggers a warning and is not passed to SDK"""
+        mock_image = Mock()
+        mock_logs = iter([])
+
+        self.mock_container_client.images.build.return_value = (mock_image, mock_logs)
+        self.client.build_image(**self.base_build_args, extra_params=["--ssh", "default"])
+        mock_log.warning.assert_called_once()
+        self.assertIn("DockerBuildExtraParams", mock_log.warning.call_args[0][0])
+
+        self.mock_container_client.images.build.assert_called_once_with(**self.base_build_args, rm=True)
+
     def test_is_available_returns_true(self):
         """Test that is_available always returns True for SDK"""
         result = SDKBuildClient.is_available("docker")
@@ -202,6 +215,28 @@ def test_build_image_handles_failure(self, mock_popen):
         self.assertIn("Build failed with exit code 1", str(context.exception))
         self.assertEqual(context.exception.build_log, [{"stream": "Step 1/5\n"}, {"stream": "Error: build failed\n"}])
 
+    @patch("samcli.local.docker.image_build_client.subprocess.Popen")
+    def test_build_image_docker_with_extra_params(self, mock_popen):
+        """Test that extra_params are appended to the docker command"""
+        mock_process = Mock()
+        mock_process.stdout = iter(["Done\n"])
+        mock_process.returncode = 0
+        mock_popen.return_value = mock_process
+
+        list(
+            self.docker_client.build_image(
+                **self.base_build_args,
+                extra_params=["--ssh", "default", "--secret", "id=mysecret,src=secret.txt"],
+            )
+        )
+
+        actual_cmd = mock_popen.call_args[0][0]
+        self.assertEqual(actual_cmd[-1], self.base_build_args["path"])
+        self.assertIn("--ssh", actual_cmd)
+        self.assertIn("default", actual_cmd)
+        self.assertIn("--secret", actual_cmd)
+        self.assertIn("id=mysecret,src=secret.txt", actual_cmd)
+
     @patch("samcli.local.docker.image_build_client.shutil.which")
     @patch("samcli.local.docker.image_build_client.subprocess.run")
     def test_is_available_docker_success(self, mock_run, mock_which):