feat(test): allow specifying simple ad-hoc distributions in LLAMA_STACK_CONFIG

tests/api/conftest.py

@@ -6,14 +6,22 @@
 import copy
 import logging
 import os
+import tempfile
 from pathlib import Path
+from typing import List
 
 import pytest
+import yaml
 from llama_stack_client import LlamaStackClient
 
 from llama_stack import LlamaStackAsLibraryClient
 from llama_stack.apis.datatypes import Api
+from llama_stack.distribution.datatypes import Provider, StackRunConfig
+from llama_stack.distribution.distribution import get_provider_registry
+from llama_stack.distribution.stack import replace_env_vars
+from llama_stack.distribution.utils.dynamic import instantiate_class_type
 from llama_stack.providers.tests.env import get_env_or_fail
+from llama_stack.providers.utils.kvstore.config import SqliteKVStoreConfig
 
 from .fixtures.recordable_mock import RecordableMock
 from .report import Report
@@ -99,11 +107,67 @@ def provider_data():
     return provider_data if len(provider_data) > 0 else None
 
 
+def distro_from_adhoc_config_spec(adhoc_config_spec: str) -> str:
+    """
+    Create an adhoc distribution from a list of API providers.
+
+    The list should be of the form "api=provider", e.g. "inference=fireworks". If you have
+    multiple pairs, separate them with commas or semicolons, e.g. "inference=fireworks,safety=llama-guard,agents=meta-reference"
+    """
+
+    api_providers = adhoc_config_spec.replace(";", ",").split(",")
+    provider_registry = get_provider_registry()
+
+    provider_configs_by_api = {}
+    for api_provider in api_providers:
+        api_str, provider = api_provider.split("=")
+        api = Api(api_str)
+
+        providers_by_type = provider_registry[api]
+        provider_spec = providers_by_type.get(provider)
+        if not provider_spec:
+            provider_spec = providers_by_type.get(f"inline::{provider}")
+        if not provider_spec:
+            provider_spec = providers_by_type.get(f"remote::{provider}")
+
+        if not provider_spec:
+            raise ValueError(
+                f"Provider {provider} (or remote::{provider} or inline::{provider}) not found for API {api}"
+            )
+
+        # call method "sample_run_config" on the provider spec config class
+        provider_config_type = instantiate_class_type(provider_spec.config_class)
+        provider_config = replace_env_vars(provider_config_type.sample_run_config())
+
+        provider_configs_by_api[api_str] = [
+            Provider(
+                provider_id=provider,
+                provider_type=provider_spec.provider_type,
+                config=provider_config,
+            )
+        ]
+    sqlite_file = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
+    run_config_file = tempfile.NamedTemporaryFile(delete=False, suffix=".yaml")
+    with open(run_config_file.name, "w") as f:
+        config = StackRunConfig(
+            image_name="distro-test",
+            apis=list(provider_configs_by_api.keys()),
+            metadata_store=SqliteKVStoreConfig(db_path=sqlite_file.name),
+            providers=provider_configs_by_api,
+        )
+        yaml.dump(config.model_dump(), f)
+
+    return run_config_file.name
+
+
 @pytest.fixture(scope="session")
-def llama_stack_client(provider_data, text_model_id):
+def llama_stack_client(request, provider_data, text_model_id):
     if os.environ.get("LLAMA_STACK_CONFIG"):
+        config = get_env_or_fail("LLAMA_STACK_CONFIG")
+        if "=" in config:
+            config = distro_from_adhoc_config_spec(config)
         client = LlamaStackAsLibraryClient(
-            get_env_or_fail("LLAMA_STACK_CONFIG"),
+            config,
             provider_data=provider_data,
             skip_logger_removal=True,
         )