filesystem_resolver.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import json
import os

import vllm.envs as envs
from vllm.lora.request import LoRARequest
from vllm.lora.resolver import LoRAResolver, LoRAResolverRegistry


class FilesystemResolver(LoRAResolver):
    def __init__(self, lora_cache_dir: str):
        self.lora_cache_dir = lora_cache_dir

    async def resolve_lora(
        self, base_model_name: str, lora_name: str
    ) -> LoRARequest | None:
        lora_path = os.path.join(self.lora_cache_dir, lora_name)
        maybe_lora_request = await self._get_lora_req_from_path(
            lora_name, lora_path, base_model_name
        )
        return maybe_lora_request

    async def _get_lora_req_from_path(
        self, lora_name: str, lora_path: str, base_model_name: str
    ) -> LoRARequest | None:
        """Builds a LoraRequest pointing to the lora path if it's a valid
        LoRA adapter and has a matching base_model_name.
        """
        if os.path.exists(lora_path):
            adapter_config_path = os.path.join(lora_path, "adapter_config.json")

            if os.path.exists(adapter_config_path):
                with open(adapter_config_path) as file:
                    adapter_config = json.load(file)
                if (
                    adapter_config["peft_type"] == "LORA"
                    and adapter_config["base_model_name_or_path"] == base_model_name
                ):
                    lora_request = LoRARequest(
                        lora_name=lora_name,
                        lora_int_id=abs(hash(lora_name)),
                        lora_path=lora_path,
                    )
                    return lora_request
        return None


def register_filesystem_resolver():
    """Register the filesystem LoRA Resolver with vLLM"""

    lora_cache_dir = envs.VLLM_LORA_RESOLVER_CACHE_DIR
    if lora_cache_dir:
        if not os.path.exists(lora_cache_dir) or not os.path.isdir(lora_cache_dir):
            raise ValueError(
                "VLLM_LORA_RESOLVER_CACHE_DIR must be set to a valid directory \
                for Filesystem Resolver plugin to function"
            )
        fs_resolver = FilesystemResolver(lora_cache_dir)
        LoRAResolverRegistry.register_resolver("Filesystem Resolver", fs_resolver)

    return