Turn `@config` into a `dataclass_transform` (#31541)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/config/pooler.py

@@ -3,8 +3,6 @@
 
 from typing import Any, Literal, get_args
 
-from pydantic.dataclasses import dataclass
-
 from vllm.config.utils import config
 from vllm.logger import init_logger
 from vllm.utils.hashing import safe_hash
@@ -19,7 +17,6 @@ TOK_POOLING_TYPES: tuple[TokenPoolingType, ...] = get_args(TokenPoolingType)
 
 
 @config
-@dataclass
 class PoolerConfig:
     """Controls the behavior of output pooling in pooling models."""
 

vllm/config/profiler.py

@@ -5,7 +5,6 @@ import os
 from typing import Any, Literal
 
 from pydantic import Field, model_validator
-from pydantic.dataclasses import dataclass
 from typing_extensions import Self
 
 from vllm.config.utils import config
@@ -32,7 +31,6 @@ def _is_uri_path(path: str) -> bool:
 
 
 @config
-@dataclass
 class ProfilerConfig:
     """Dataclass which contains profiler config for the engine."""
 

vllm/config/scheduler.py

@@ -6,7 +6,6 @@ from dataclasses import InitVar
 from typing import TYPE_CHECKING, Any, ClassVar, Literal, cast
 
 from pydantic import Field, field_validator
-from pydantic.dataclasses import dataclass
 from typing_extensions import Self
 
 from vllm.config.utils import config
@@ -24,7 +23,6 @@ SchedulerPolicy = Literal["fcfs", "priority"]
 
 
 @config
-@dataclass
 class SchedulerConfig:
     """Scheduler configuration."""
 

vllm/config/speculative.py

@@ -5,7 +5,6 @@ import ast
 from typing import TYPE_CHECKING, Any, Literal, get_args
 
 from pydantic import Field, SkipValidation, model_validator
-from pydantic.dataclasses import dataclass
 from typing_extensions import Self
 
 from vllm.config.model import ModelConfig
@@ -55,7 +54,6 @@ SpeculativeMethod = Literal[
 
 
 @config
-@dataclass
 class SpeculativeConfig:
     """Configuration for speculative decoding."""
 

vllm/config/speech_to_text.py

@@ -2,13 +2,10 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 
-from pydantic.dataclasses import dataclass
-
 from vllm.config.utils import config
 
 
 @config
-@dataclass
 class SpeechToTextConfig:
     """Configuration for speech-to-text models."""
 

vllm/config/structured_outputs.py

@@ -4,7 +4,6 @@
 from typing import Any, Literal
 
 from pydantic import model_validator
-from pydantic.dataclasses import dataclass
 from typing_extensions import Self
 
 from vllm.config.utils import config
@@ -16,7 +15,6 @@ StructuredOutputsBackend = Literal[
 
 
 @config
-@dataclass
 class StructuredOutputsConfig:
     """Dataclass which contains structured outputs config for the engine."""
 

vllm/config/utils.py

@@ -10,14 +10,17 @@ import json
 import pathlib
 import textwrap
 from collections.abc import Callable, Mapping, Sequence, Set
-from dataclasses import MISSING, Field, dataclass, field, fields, is_dataclass, replace
+from dataclasses import MISSING, Field, field, fields, is_dataclass
 from itertools import pairwise
-from typing import TYPE_CHECKING, Any, Protocol, TypeVar
+from typing import TYPE_CHECKING, Any, Protocol, TypeVar, cast
 
 import regex as re
 import torch
+from pydantic import ConfigDict
+from pydantic.dataclasses import dataclass
+from pydantic.fields import Field as PydanticField
 from pydantic.fields import FieldInfo
-from typing_extensions import runtime_checkable
+from typing_extensions import dataclass_transform, runtime_checkable
 
 from vllm.logger import init_logger
 
@@ -29,23 +32,39 @@ else:
     DataclassInstance = Any
 
 ConfigType = type[DataclassInstance]
-ConfigT = TypeVar("ConfigT", bound=ConfigType)
+ConfigT = TypeVar("ConfigT", bound=DataclassInstance)
 
 
-def config(cls: ConfigT) -> ConfigT:
-    """
-    A decorator that ensures all fields in a dataclass have default values
-    and that each field has a docstring.
+@dataclass_transform(field_specifiers=(PydanticField,))
+def config(
+    cls: type[ConfigT] | None = None,
+    *,
+    config: ConfigDict | None = None,
+    **kwargs: Any,
+) -> type[ConfigT] | Callable[[type[ConfigT]], type[ConfigT]]:
+    """Decorator to create a pydantic dataclass with default config. The default config
+    for the dataclass forbids extra fields.
 
-    If a `ConfigT` is used as a CLI argument itself, the `type` keyword argument
-    provided by `get_kwargs` will be
-    `pydantic.TypeAdapter(ConfigT).validate_json(cli_arg)` which treats the
-    `cli_arg` as a JSON string which gets validated by `pydantic`.
+    All config classes in vLLM should use this decorator.
 
-    Config validation is performed by the tools/pre_commit/validate_config.py
-    script, which is invoked during the pre-commit checks.
-    """
-    return cls
+    Args:
+        cls: The class to decorate
+        config: The pydantic ConfigDict to use. If provided, it will be merged with
+            the default config.
+        **kwargs: Additional arguments to pass to pydantic.dataclass."""
+    # Extra fields are forbidden by default
+    merged_config = ConfigDict(extra="forbid")
+    if config is not None:
+        merged_config.update(config)
+
+    def decorator(cls):
+        return dataclass(cls, config=merged_config, **kwargs)
+
+    # Called with arguments: @config(config=...)
+    if cls is None:
+        return decorator
+    # Called without arguments: @config
+    return decorator(cls)
 
 
 def get_field(cls: ConfigType, name: str) -> Field:
@@ -53,24 +72,46 @@ def get_field(cls: ConfigType, name: str) -> Field:
     default factory fields in `EngineArgs`."""
     if not is_dataclass(cls):
         raise TypeError("The given class is not a dataclass.")
-    cls_fields = {f.name: f for f in fields(cls)}
-    if name not in cls_fields:
-        raise ValueError(f"Field '{name}' not found in {cls.__name__}.")
-    named_field: Field = cls_fields[name]
-    if (default_factory := named_field.default_factory) is not MISSING:
-        return field(default_factory=default_factory)
-    if (default := named_field.default) is not MISSING:
+    try:
+        named_field = next(f for f in fields(cls) if f.name == name)
+    except StopIteration as e:
+        raise ValueError(f"Field '{name}' not found in {cls.__name__}.") from e
+
+    # The arguments to copy to the new field
+    default = named_field.default
+    default_factory = named_field.default_factory
+    init = named_field.init
+
+    # Handle pydantic.Field
     if isinstance(default, FieldInfo):
-            # Handle pydantic.Field defaults
+        if default.init is not None:
+            init = default.init
         if default.default_factory is not None:
-                return field(default_factory=default.default_factory)
+            default_factory = cast(Callable[[], Any], default.default_factory)
+            default = MISSING
         else:
             default = default.default
-        return field(default=default)
 
-    raise ValueError(
-        f"{cls.__name__}.{name} must have a default value or default factory."
+    if default is MISSING and default_factory is MISSING:
+        logger.warning_once(
+            "%s.%s has no default or default factory.", cls.__name__, name
         )
+    return field(default=default, default_factory=default_factory, init=init)
+
+
+def is_init_field(cls: ConfigType, name: str) -> bool:
+    return get_field(cls, name).init
+
+
+def replace(dataclass_instance: ConfigT, /, **kwargs) -> ConfigT:
+    """Like [`dataclasses.replace`](https://docs.python.org/3/library/dataclasses.html#dataclasses.replace),
+    but compatible with Pydantic dataclasses which use `pydantic.fields.Field` instead
+    of `dataclasses.field`"""
+    cls = type(dataclass_instance)
+    dataclass_dict = dataclass_instance.__dict__
+    dataclass_dict = {k: v for k, v in dataclass_dict.items() if is_init_field(cls, k)}
+    dataclass_dict.update(kwargs)
+    return cls(**dataclass_dict)
 
 
 def getattr_iter(
@@ -172,10 +213,6 @@ def get_attr_docs(cls: type[Any]) -> dict[str, str]:
     return out
 
 
-def is_init_field(cls: ConfigType, name: str) -> bool:
-    return next(f for f in fields(cls) if f.name == name).init
-
-
 @runtime_checkable
 class SupportsHash(Protocol):
     def compute_hash(self) -> str: ...

vllm/config/vllm.py

@@ -9,7 +9,7 @@ import tempfile
 import threading
 import time
 from contextlib import contextmanager
-from dataclasses import is_dataclass, replace
+from dataclasses import is_dataclass
 from datetime import datetime
 from enum import IntEnum
 from functools import lru_cache
@@ -18,10 +18,8 @@ from typing import TYPE_CHECKING, Any, TypeVar, get_args
 
 import torch
 from pydantic import ConfigDict, Field, model_validator
-from pydantic.dataclasses import dataclass
 
 import vllm.envs as envs
-from vllm.config.speculative import EagleModelTypes
 from vllm.logger import enable_trace_function_call, init_logger
 from vllm.transformers_utils.runai_utils import is_runai_obj_uri
 from vllm.utils import random_uuid
@@ -41,9 +39,9 @@ from .observability import ObservabilityConfig
 from .parallel import ParallelConfig
 from .profiler import ProfilerConfig
 from .scheduler import SchedulerConfig
-from .speculative import SpeculativeConfig
+from .speculative import EagleModelTypes, SpeculativeConfig
 from .structured_outputs import StructuredOutputsConfig
-from .utils import SupportsHash, config
+from .utils import SupportsHash, config, replace
 
 if TYPE_CHECKING:
     from transformers import PretrainedConfig
@@ -187,8 +185,7 @@ OPTIMIZATION_LEVEL_TO_CONFIG = {
 }
 
 
-@config
-@dataclass(config=ConfigDict(arbitrary_types_allowed=True))
+@config(config=ConfigDict(arbitrary_types_allowed=True))
 class VllmConfig:
     """Dataclass which contains all vllm-related configuration. This
     simplifies passing around the distinct configurations in the codebase.
@@ -1395,14 +1392,6 @@ class VllmConfig:
         path = self.compilation_config.debug_dump_path / append_path
         return path
 
-    def replace(self, **kwargs):
-        """
-        Replace attributes of the config, and 'recompute' the config.
-        dataclass.replace() calls __init__() and __post_init__(), source:
-        https://docs.python.org/3/library/dataclasses.html#dataclasses.replace
-        """
-        return replace(self, **kwargs)
-
     def __str__(self):
         return (
             f"model={self.model_config.model!r}, "

vllm/entrypoints/openai/cli_args.py

@@ -13,8 +13,6 @@ from collections.abc import Sequence
 from dataclasses import field
 from typing import Any, Literal
 
-from pydantic.dataclasses import dataclass
-
 import vllm.envs as envs
 from vllm.config import config
 from vllm.engine.arg_utils import AsyncEngineArgs, optional_type
@@ -69,7 +67,6 @@ class LoRAParserAction(argparse.Action):
 
 
 @config
-@dataclass
 class FrontendArgs:
     """Arguments for the OpenAI-compatible frontend server."""
 

vllm/transformers_utils/configs/speculators/algos.py

@@ -13,9 +13,10 @@ def register_speculator(name):
 
 
 @register_speculator("eagle3")
-def update_eagle3(config_dict: dict, vllm_config: dict) -> None:
+def update_eagle3(config_dict: dict, pre_trained_config: dict) -> None:
     """
-    Apply Eagle-3 specific configuration transformations.
+    Apply Eagle-3 specific configuration transformations to the `dict` used to
+    construct the Transformers PreTrainedConfig.
 
     Eagle-3 specific fields:
     - draft_vocab_size: Size of the draft model's vocabulary
@@ -27,12 +28,14 @@ def update_eagle3(config_dict: dict, vllm_config: dict) -> None:
         predictions. This is the standard field used in Eagle3 checkpoints.
     """
 
-    vllm_config["draft_vocab_size"] = config_dict.get("draft_vocab_size")
+    pre_trained_config["draft_vocab_size"] = config_dict.get("draft_vocab_size")
     if config_dict.get("target_hidden_size") is not None:
-        vllm_config["target_hidden_size"] = config_dict["target_hidden_size"]
-    vllm_config["norm_before_residual"] = config_dict.get("norm_before_residual", True)
-    vllm_config["architectures"] = ["Eagle3LlamaForCausalLM"]
+        pre_trained_config["target_hidden_size"] = config_dict["target_hidden_size"]
+    pre_trained_config["norm_before_residual"] = config_dict.get(
+        "norm_before_residual", True
+    )
+    pre_trained_config["architectures"] = ["Eagle3LlamaForCausalLM"]
     if config_dict.get("eagle_aux_hidden_state_layer_ids"):
-        vllm_config["eagle_aux_hidden_state_layer_ids"] = config_dict[
+        pre_trained_config["eagle_aux_hidden_state_layer_ids"] = config_dict[
             "eagle_aux_hidden_state_layer_ids"
         ]

vllm/transformers_utils/configs/speculators/base.py

@@ -24,13 +24,16 @@ class SpeculatorsConfig(PretrainedConfig):
         """Load speculators Eagle config and convert to vLLM format."""
         config_dict, _ = cls.get_config_dict(pretrained_model_name_or_path, **kwargs)
 
-        vllm_config = cls.extract_vllm_speculative_config(config_dict)
+        vllm_config = cls.extract_transformers_pre_trained_config(config_dict)
         return cls(**vllm_config)
 
     @classmethod
-    def extract_vllm_speculative_config(
+    def extract_transformers_pre_trained_config(
         cls, config_dict: dict[str, Any]
     ) -> dict[str, Any]:
+        """
+        Extract standard Transformers PreTrainedConfig config from speculators config.
+        """
         speculators_model_type = config_dict.get("speculators_model_type")
         if speculators_model_type not in SUPPORTED_SPECULATORS_TYPES:
             raise ValueError(
@@ -38,15 +41,23 @@ class SpeculatorsConfig(PretrainedConfig):
                 "Please ensure you're loading a speculators-format model."
             )
 
+        # Start with transformer layer configuration if present
+        pre_trained_config = config_dict.get("transformer_layer_config", {})
+        # Apply anything specific to the supported algorithm
+        algo_updater = SUPPORTED_SPECULATORS_TYPES[speculators_model_type]
+        algo_updater(config_dict=config_dict, pre_trained_config=pre_trained_config)
+        return pre_trained_config
+
+    @classmethod
+    def extract_vllm_speculative_config(
+        cls, config_dict: dict[str, Any]
+    ) -> dict[str, Any]:
+        """Extract vLLM speculative config from speculators config."""
         # validate fields
         # TODO: @dsikka - use speculators pydantic model to validate
         cls.validate_speculators_config(config_dict=config_dict)
         # Convert from speculators config -> format that can be ingested by vLLM
-        vllm_config = cls.build_vllm_speculative_config(config_dict=config_dict)
-        # Apply anything specific to the supported algorithm
-        algo_updater = SUPPORTED_SPECULATORS_TYPES[speculators_model_type]
-        algo_updater(config_dict=config_dict, vllm_config=vllm_config)
-        return vllm_config
+        return cls.build_vllm_speculative_config(config_dict=config_dict)
 
     @classmethod
     def validate_speculators_config(cls, config_dict: dict[str, Any]) -> None:
@@ -101,14 +112,7 @@ class SpeculatorsConfig(PretrainedConfig):
             )
 
         # Build base vLLM speculative configuration
-        vllm_config = {
+        return {
             "method": config_dict.get("speculators_model_type"),
             "num_speculative_tokens": num_speculative_tokens,
-            "target_model": spec_config.get("verifier")["name_or_path"],
         }
-
-        # Merge transformer layer configuration if present
-        transformer_config = config_dict.get("transformer_layer_config", {})
-        vllm_config.update(transformer_config)
-
-        return vllm_config

vllm/v1/spec_decode/draft_model.py

@@ -4,7 +4,7 @@ from typing import Any
 
 import torch
 
-from vllm.config import VllmConfig, get_layers_from_vllm_config
+from vllm.config import VllmConfig, get_layers_from_vllm_config, replace
 from vllm.logger import init_logger
 from vllm.model_executor.layers.attention import Attention
 from vllm.model_executor.model_loader import get_model
@@ -191,10 +191,12 @@ def create_vllm_config_for_draft_model(
     old = target_model_vllm_config
     assert old.speculative_config is not None, "speculative_config is not set"
     old_spec_config = old.speculative_config
-    new_parallel_config = old_spec_config.draft_parallel_config.replace(
-        rank=old.parallel_config.rank
+    new_parallel_config = replace(
+        old_spec_config.draft_parallel_config,
+        rank=old.parallel_config.rank,
     )
-    new: VllmConfig = old.replace(
+    new: VllmConfig = replace(
+        old,
         quant_config=None,  # quant_config is recomputed in __init__()
         model_config=old_spec_config.draft_model_config,
         parallel_config=new_parallel_config,