Add support for --external to esbuild configuration

aws_lambda_builders/workflows/nodejs_npm_esbuild/actions.py

@@ -54,6 +54,9 @@ def __init__(
 
         :type skip_deps: bool
         :param skip_deps: if dependencies should be omitted from bundling
+
+        :type bundler_config: Dict[str,Any]
+        :param bundler_config: the bundler configuration
         """
         super(EsbuildBundleAction, self).__init__()
         self.scratch_dir = scratch_dir
@@ -71,38 +74,26 @@ def execute(self):
         :raises lambda_builders.actions.ActionFailedError: when esbuild packaging fails
         """
 
-        if self.ENTRY_POINTS not in self.bundler_config:
-            raise ActionFailedError(f"{self.ENTRY_POINTS} not set ({self.bundler_config})")
-
-        entry_points = self.bundler_config[self.ENTRY_POINTS]
-
-        if not isinstance(entry_points, list):
-            raise ActionFailedError(f"{self.ENTRY_POINTS} must be a list ({self.bundler_config})")
-
-        if not entry_points:
-            raise ActionFailedError(f"{self.ENTRY_POINTS} must not be empty ({self.bundler_config})")
-
-        entry_paths = [self.osutils.joinpath(self.scratch_dir, entry_point) for entry_point in entry_points]
-
-        LOG.debug("NODEJS building %s using esbuild to %s", entry_paths, self.artifacts_dir)
-
-        explicit_entry_points = []
-        for entry_path, entry_point in zip(entry_paths, entry_points):
-            explicit_entry_points.append(self._get_explicit_file_type(entry_point, entry_path))
+        explicit_entry_points = self._construct_esbuild_entry_points()
 
         args = explicit_entry_points + ["--bundle", "--platform=node", "--format=cjs"]
         minify = self.bundler_config.get("minify", True)
         sourcemap = self.bundler_config.get("sourcemap", True)
         target = self.bundler_config.get("target", "es2020")
+        externals = self.bundler_config.get("externals", [])
         if minify:
             args.append("--minify")
         if sourcemap:
             args.append("--sourcemap")
+        if externals:
+            args.extend(map(lambda x: f"--external:{x}", externals))
+
         args.append("--target={}".format(target))
         args.append("--outdir={}".format(self.artifacts_dir))
 
         if self.skip_deps:
             LOG.info("Running custom esbuild using Node.js")
+            # Don't pass externals because the esbuild.js template makes everything external
             script = EsbuildBundleAction._get_node_esbuild_template(
                 explicit_entry_points, target, self.artifacts_dir, minify, sourcemap
             )
@@ -132,6 +123,30 @@ def _run_external_esbuild_in_nodejs(self, script):
             except EsbuildExecutionError as ex:
                 raise ActionFailedError(str(ex))
 
+    def _construct_esbuild_entry_points(self):
+        """
+        Construct the list of explicit entry points
+        """
+        if self.ENTRY_POINTS not in self.bundler_config:
+            raise ActionFailedError(f"{self.ENTRY_POINTS} not set ({self.bundler_config})")
+
+        entry_points = self.bundler_config[self.ENTRY_POINTS]
+
+        if not isinstance(entry_points, list):
+            raise ActionFailedError(f"{self.ENTRY_POINTS} must be a list ({self.bundler_config})")
+
+        if not entry_points:
+            raise ActionFailedError(f"{self.ENTRY_POINTS} must not be empty ({self.bundler_config})")
+
+        entry_paths = [self.osutils.joinpath(self.scratch_dir, entry_point) for entry_point in entry_points]
+
+        LOG.debug("NODEJS building %s using esbuild to %s", entry_paths, self.artifacts_dir)
+
+        explicit_entry_points = []
+        for entry_path, entry_point in zip(entry_paths, entry_points):
+            explicit_entry_points.append(self._get_explicit_file_type(entry_point, entry_path))
+        return explicit_entry_points
+
     @staticmethod
     def _get_node_esbuild_template(entry_points, target, out_dir, minify, sourcemap):
         """

tests/unit/workflows/nodejs_npm_esbuild/test_actions.py

@@ -70,6 +70,31 @@ def test_packages_javascript_with_minification_and_sourcemap(self):
             cwd="source",
         )
 
+    def test_adds_externals(self):
+        action = EsbuildBundleAction(
+            "source",
+            "artifacts",
+            {"entry_points": ["x.js"], "externals": ["fetch", "aws-sdk"]},
+            self.osutils,
+            self.subprocess_esbuild,
+        )
+        action.execute()
+        self.subprocess_esbuild.run.assert_called_with(
+            [
+                "x.js",
+                "--bundle",
+                "--platform=node",
+                "--format=cjs",
+                "--minify",
+                "--sourcemap",
+                "--external:fetch",
+                "--external:aws-sdk",
+                "--target=es2020",
+                "--outdir=artifacts",
+            ],
+            cwd="source",
+        )
+
     def test_checks_if_single_entrypoint_exists(self):
 
         action = EsbuildBundleAction(