fix: stop image_name from being cast to an integer (#2759)

# What does this PR do?

https://github.com/meta-llama/llama-stack/pull/2490 introduced a new
function for type conversion of strings.

However, a side effect of this is that it will cast any string that can
be cast to an integer if possible, which for something like `image_name`
is not desired as we only accept strings for this field in the
`StackRunConfig`

This PR introduces logic to ensure that `image_name` remains a string 

Closes #2749

## Test Plan

You can run the original step to reproduce from the bug to verify this
manually
```bash
OPENAI_API_KEY=bogus llama stack build --image-type venv --image-name 2745 --providers inference=remote::openai --run
```

I have also added an additional unit test to prevent any future
regression here

Signed-off-by: Nathan Weinberg <nweinber@redhat.com>

llama_stack/distribution/configure.py

@@ -17,7 +17,7 @@ from llama_stack.distribution.distribution import (
     builtin_automatically_routed_apis,
     get_provider_registry,
 )
-from llama_stack.distribution.stack import replace_env_vars
+from llama_stack.distribution.stack import cast_image_name_to_string, replace_env_vars
 from llama_stack.distribution.utils.config_dirs import EXTERNAL_PROVIDERS_DIR
 from llama_stack.distribution.utils.dynamic import instantiate_class_type
 from llama_stack.distribution.utils.prompt_for_config import prompt_for_config
@@ -164,7 +164,8 @@ def upgrade_from_routing_table(
 def parse_and_maybe_upgrade_config(config_dict: dict[str, Any]) -> StackRunConfig:
     version = config_dict.get("version", None)
     if version == LLAMA_STACK_RUN_CONFIG_VERSION:
-        return StackRunConfig(**replace_env_vars(config_dict))
+        processed_config_dict = replace_env_vars(config_dict)
+        return StackRunConfig(**cast_image_name_to_string(processed_config_dict))
 
     if "routing_table" in config_dict:
         logger.info("Upgrading config...")
@@ -175,4 +176,5 @@ def parse_and_maybe_upgrade_config(config_dict: dict[str, Any]) -> StackRunConfi
     if not config_dict.get("external_providers_dir", None):
         config_dict["external_providers_dir"] = EXTERNAL_PROVIDERS_DIR
 
-    return StackRunConfig(**replace_env_vars(config_dict))
+    processed_config_dict = replace_env_vars(config_dict)
+    return StackRunConfig(**cast_image_name_to_string(processed_config_dict))

llama_stack/distribution/server/server.py

@@ -47,6 +47,7 @@ from llama_stack.distribution.server.routes import (
     initialize_route_impls,
 )
 from llama_stack.distribution.stack import (
+    cast_image_name_to_string,
     construct_stack,
     replace_env_vars,
     validate_env_pair,
@@ -439,7 +440,7 @@ def main(args: argparse.Namespace | None = None):
                     logger.error(f"Error: {str(e)}")
                     sys.exit(1)
         config = replace_env_vars(config_contents)
-        config = StackRunConfig(**config)
+        config = StackRunConfig(**cast_image_name_to_string(config))
 
     # now that the logger is initialized, print the line about which type of config we are using.
     logger.info(log_line)

llama_stack/distribution/stack.py

@@ -267,6 +267,13 @@ def _convert_string_to_proper_type(value: str) -> Any:
     return value
 
 
+def cast_image_name_to_string(config_dict: dict[str, Any]) -> dict[str, Any]:
+    """Ensure that any value for a key 'image_name' in a config_dict is a string"""
+    if "image_name" in config_dict and config_dict["image_name"] is not None:
+        config_dict["image_name"] = str(config_dict["image_name"])
+    return config_dict
+
+
 def validate_env_pair(env_pair: str) -> tuple[str, str]:
     """Validate and split an environment variable key-value pair."""
     try:

tests/unit/cli/test_stack_config.py

@@ -15,6 +15,37 @@ from llama_stack.distribution.configure import (
 )
 
 
+@pytest.fixture
+def config_with_image_name_int():
+    return yaml.safe_load(
+        f"""
+        version: {LLAMA_STACK_RUN_CONFIG_VERSION}
+        image_name: 1234
+        apis_to_serve: []
+        built_at: {datetime.now().isoformat()}
+        providers:
+          inference:
+            - provider_id: provider1
+              provider_type: inline::meta-reference
+              config: {{}}
+          safety:
+            - provider_id: provider1
+              provider_type: inline::meta-reference
+              config:
+                llama_guard_shield:
+                  model: Llama-Guard-3-1B
+                  excluded_categories: []
+                  disable_input_check: false
+                  disable_output_check: false
+                enable_prompt_guard: false
+          memory:
+            - provider_id: provider1
+              provider_type: inline::meta-reference
+              config: {{}}
+    """
+    )
+
+
 @pytest.fixture
 def up_to_date_config():
     return yaml.safe_load(
@@ -125,3 +156,8 @@ def test_parse_and_maybe_upgrade_config_old_format(old_config):
 def test_parse_and_maybe_upgrade_config_invalid(invalid_config):
     with pytest.raises(KeyError):
         parse_and_maybe_upgrade_config(invalid_config)
+
+
+def test_parse_and_maybe_upgrade_config_image_name_int(config_with_image_name_int):
+    result = parse_and_maybe_upgrade_config(config_with_image_name_int)
+    assert isinstance(result.image_name, str)