feat: Enhanced Model Provider Support and Configuration Flexibility For Rag Service (#2056)

Co-authored-by: doodleEsc <cokie@foxmail.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

py/rag-service/src/providers/openrouter.py

@@ -0,0 +1,35 @@
+# src/providers/openrouter.py
+
+from typing import Any
+
+from llama_index.core.llms.llm import LLM
+from llama_index.llms.openrouter import OpenRouter
+
+
+def initialize_llm_model(
+    llm_endpoint: str,
+    llm_api_key: str,
+    llm_model: str,
+    **llm_extra: Any,  # noqa: ANN401
+) -> LLM:
+    """
+    Create OpenRouter LLM model.
+
+    Args:
+        llm_model: The name of the LLM model.
+        llm_endpoint: The API endpoint for the OpenRouter API.
+        llm_api_key: The API key for the OpenRouter API.
+        llm_extra: The Extra Parameters for OpenROuter,
+
+    Returns:
+        The initialized llm_model.
+
+    """
+    # Use the provided endpoint directly.
+    # We are not using llm_api_key parameter here, relying on env var as original code did.
+    return OpenRouter(
+        model=llm_model,
+        api_base=llm_endpoint,
+        api_key=llm_api_key,
+        **llm_extra,
+    )