Change allowed_instance_types to accept list instead of space-delimit…

[PratibhaShrivastav18]

allowed_instance_types — Breaking Change

CLI (YAML input)

Before:

allowed_instance_types: Standard_DS3_v2 Standard_DS4_v2

After:

allowed_instance_types:
  - Standard_DS3_v2
  - Standard_DS4_v2

SDK

Before:

# Both str and list accepted
DeploymentTemplate(allowed_instance_types="Standard_DS3_v2 Standard_DS4_v2")
DeploymentTemplate(allowed_instance_types=["Standard_DS3_v2", "Standard_DS4_v2"])

After:

# Only list accepted
DeploymentTemplate(allowed_instance_types=["Standard_DS3_v2", "Standard_DS4_v2"])

If an SDK is being regenerated based on a new API spec, a link to the pull request containing these API spec changes should be included above.

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull request overview

This PR updates allowed_instance_types to be represented as a YAML/SDK list (rather than a single space-delimited string), aligning schema + entity serialization with the service’s array shape.

Changes:

• Updated DeploymentTemplateSchema to parse allowed_instance_types as List[str].
• Updated DeploymentTemplate to type allowed_instance_types as Optional[List[str]] and to serialize it directly as allowedInstanceTypes.
• Removed string-splitting conversion in DeploymentTemplateOperations._convert_dict_to_deployment_template, and updated one unit test to use a list.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
sdk/ml/azure-ai-ml/tests/deployment_template/unittests/test_deployment_template.py	Updates initialization assertion to use list form for allowed_instance_types.
sdk/ml/azure-ai-ml/azure/ai/ml/operations/_deployment_template_operations.py	Stops converting string allowed_instance_types into a list during dict-to-entity conversion.
sdk/ml/azure-ai-ml/azure/ai/ml/entities/_deployment/deployment_template.py	Changes allowed_instance_types typing to List[str] and passes through list directly in REST serialization.
sdk/ml/azure-ai-ml/azure/ai/ml/_schema/_deployment/template/deployment_template.py	Changes marshmallow schema field type from Str to List(Str).

[Copilot]

allowed_instance_types is now annotated as Optional[List[str]], but the constructor assigns it without runtime validation. As a result, callers can still pass a string (or other non-list types) and the object will accept it, contradicting the PR’s stated breaking change and potentially leading to invalid REST payloads later. Add explicit type/element validation here (e.g., reject str, ensure it’s a list of str) and raise a clear error.

[Copilot]

_to_rest_object now forwards self.allowed_instance_types directly to allowedInstanceTypes without coercion or validation. If a non-list slips through (e.g., a str from user code), this will produce an invalid request body and fail at service call time. Validate/normalize before setting the REST field (and prefer failing fast with a helpful exception).

Suggested change

	result["allowedInstanceTypes"] = self.allowed_instance_types # type: ignore[assignment]
	allowed_instance_types = self.allowed_instance_types
	if isinstance(allowed_instance_types, tuple):
	allowed_instance_types = list(allowed_instance_types)
	elif isinstance(allowed_instance_types, (str, bytes)) or not isinstance(allowed_instance_types, list):
	raise TypeError(
	"allowed_instance_types must be a list of strings when provided."
	)
	if not all(isinstance(instance_type, str) for instance_type in allowed_instance_types):
	raise TypeError(
	"allowed_instance_types must be a list of strings when provided."
	)
	result["allowedInstanceTypes"] = allowed_instance_types # type: ignore[assignment]

[Copilot]

_convert_dict_to_deployment_template no longer converts string allowed_instance_types values, but it also doesn’t reject them. This means a user-provided dict can still contain a space-delimited string and the operation will construct a DeploymentTemplate carrying a str, which later becomes an invalid REST payload. If the intent is to make this a breaking change, add a type check here and raise a clear error when allowed_instance_types is a str (and update the related unit test that currently expects string splitting).

Suggested change

	allowed_instance_types = get_field_value(data, "allowed_instance_types", "allowedInstanceTypes")
	allowed_instance_types = get_field_value(data, "allowed_instance_types", "allowedInstanceTypes")
	if isinstance(allowed_instance_types, str):
	raise ValueError(
	"allowed_instance_types must be an iterable of strings, not a space-delimited string."
	)

[Copilot]

The updated test only asserts the list form works, but it doesn’t cover the breaking behavior described in the PR (string input should no longer be accepted). Add a unit test asserting that passing a string allowed_instance_types raises a clear exception, so the breaking change is enforced and regressions are caught.

Suggested change

	def test_deployment_template_rejects_string_allowed_instance_types(self):
	"""Test that string input for allowed_instance_types is rejected."""
	with pytest.raises((TypeError, ValueError), match=r"allowed_instance_types.*list"):
	DeploymentTemplate(
	name="test-template",
	version="1.0",
	allowed_instance_types="Standard_DS3_v2",
	)