fix: Return non-zero exit code on lint failures

samcli/commands/exceptions.py

@@ -139,3 +139,9 @@ class InvalidStackNameException(UserException):
     """
     Value provided to --stack-name is invalid
     """
+
+
+class LinterRuleMatchedException(UserException):
+    """
+    The linter matched a rule meaning that the template linting failed
+    """

samcli/commands/validate/validate.py

@@ -12,6 +12,7 @@
 from samcli.cli.main import pass_context, common_options as cli_framework_options, aws_creds_options, print_cmdline_args
 from samcli.commands._utils.cdk_support_decorators import unsupported_command_cdk
 from samcli.commands._utils.options import template_option_without_build
+from samcli.commands.exceptions import LinterRuleMatchedException
 from samcli.lib.telemetry.event import EventTracker
 from samcli.lib.telemetry.metric import track_command
 from samcli.cli.cli_config_file import configuration_option, TomlProvider
@@ -146,12 +147,18 @@ def _lint(ctx: Context, template: str) -> None:
         matches = list(cfnlint.core.get_matches(filenames, args))
         if not matches:
             click.secho("{} is a valid SAM Template".format(template), fg="green")
+            return
+
         rules = cfnlint.core.get_used_rules()
         matches_output = formatter.print_matches(matches, rules, filenames)
 
         if matches_output:
             click.secho(matches_output)
 
+        raise LinterRuleMatchedException(
+            "Linting failed. At least one linting rule was matched to the provided template."
+        )
+
     except cfnlint.core.InvalidRegionException as e:
         raise UserException(
             "AWS Region was not found. Please configure your region through the --region option",

tests/integration/validate/test_validate_command.py

@@ -162,3 +162,4 @@ def test_lint_invalid_template(self):
         )
 
         self.assertIn(warning_message, output)
+        self.assertEqual(command_result.process.returncode, 1)

tests/unit/commands/validate/test_cli.py

@@ -6,7 +6,7 @@
 
 from cfnlint.core import CfnLintExitException, InvalidRegionException  # type: ignore
 
-from samcli.commands.exceptions import UserException
+from samcli.commands.exceptions import UserException, LinterRuleMatchedException
 from samcli.commands.local.cli_common.user_exceptions import SamTemplateNotFoundException, InvalidSamTemplateException
 from samcli.commands.validate.lib.exceptions import InvalidSamDocumentException
 from samcli.commands.validate.validate import do_cli, _read_sam_file, _lint
@@ -124,5 +124,19 @@ def test_lint_event_recorded(self, click_patch):
         template_path = "path_to_template"
 
         with patch("samcli.lib.telemetry.event.EventTracker.track_event") as track_patch:
-            _lint(ctx=ctx_lint_mock(debug=False, region="region"), template=template_path)
+            with self.assertRaises(LinterRuleMatchedException):
+                _lint(ctx=ctx_lint_mock(debug=False, region="region"), template=template_path)
             track_patch.assert_called_with("UsedFeature", "CFNLint")
+
+    @patch("cfnlint.core.get_args_filenames")
+    @patch("cfnlint.core.get_matches")
+    @patch("samcli.commands.validate.validate.click")
+    def test_linter_raises_exception_if_matches_found(self, click_patch, matches_patch, args_patch):
+        template_path = "path_to_template"
+        args_patch.return_value = ("A", "B", Mock())
+        matches_patch.return_value = ["Failed rule A", "Failed rule B"]
+        with self.assertRaises(LinterRuleMatchedException) as ex:
+            _lint(ctx=ctx_lint_mock(debug=False, region="region"), template=template_path)
+        self.assertEqual(
+            ex.exception.message, "Linting failed. At least one linting rule was matched to the provided template."
+        )