Adds validation to image_spec for list of strings (flyteorg#2655)

Signed-off-by: Thomas J. Fan <thomasjpfan@gmail.com>
Signed-off-by: mao3267 <chenvincent610@gmail.com>

flytekit/image_spec/image_spec.py

@@ -81,6 +81,23 @@ def __post_init__(self):
         if self.registry:
             self.registry = self.registry.lower()
 
+        parameters_str_list = [
+            "packages",
+            "conda_channels",
+            "conda_packages",
+            "apt_packages",
+            "pip_extra_index_url",
+            "entrypoint",
+            "commands",
+        ]
+        for parameter in parameters_str_list:
+            attr = getattr(self, parameter)
+            parameter_is_None = attr is None
+            parameter_is_list_string = isinstance(attr, list) and all(isinstance(v, str) for v in attr)
+            if not (parameter_is_None or parameter_is_list_string):
+                error_msg = f"{parameter} must be a list of strings or None"
+                raise ValueError(error_msg)
+
     def image_name(self) -> str:
         """Full image name with tag."""
         image_name = self._image_name()

tests/flytekit/unit/core/image_spec/test_image_spec.py

@@ -138,3 +138,19 @@ def test_no_build_during_execution():
         ImageBuildEngine.build(spec)
 
     ImageBuildEngine._build_image.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "parameter_name", [
+        "packages", "conda_channels", "conda_packages",
+        "apt_packages", "pip_extra_index_url", "entrypoint", "commands"
+    ]
+)
+@pytest.mark.parametrize("value", ["requirements.txt", [1, 2, 3]])
+def test_image_spec_validation_string_list(parameter_name, value):
+    msg = f"{parameter_name} must be a list of strings or None"
+
+    input_params = {parameter_name: value}
+
+    with pytest.raises(ValueError, match=msg):
+        ImageSpec(**input_params)