from __future__ import annotations
import json
import warnings
from abc import ABC
from typing import TYPE_CHECKING, Any, Dict, Iterator, List, Mapping, Optional
from langchain_core.callbacks import CallbackManagerForLLMRun
from langchain_core.language_models.llms import LLM
from langchain_core.outputs import GenerationChunk
from langchain_core.pydantic_v1 import BaseModel, Extra, Field, root_validator
from langchain_core.utils import get_from_dict_or_env
from langchain_community.llms.utils import enforce_stop_tokens
from langchain_community.utilities.anthropic import (
get_num_tokens_anthropic,
get_token_ids_anthropic,
)
if TYPE_CHECKING:
from botocore.config import Config
HUMAN_PROMPT = "\n\nHuman:"
ASSISTANT_PROMPT = "\n\nAssistant:"
ALTERNATION_ERROR = (
"Error: Prompt must alternate between '\n\nHuman:' and '\n\nAssistant:'."
)
def _add_newlines_before_ha(input_text: str) -> str:
new_text = input_text
for word in ["Human:", "Assistant:"]:
new_text = new_text.replace(word, "\n\n" + word)
for i in range(2):
new_text = new_text.replace("\n\n\n" + word, "\n\n" + word)
return new_text
def _human_assistant_format(input_text: str) -> str:
if input_text.count("Human:") == 0 or (
input_text.find("Human:") > input_text.find("Assistant:")
and "Assistant:" in input_text
):
input_text = HUMAN_PROMPT + " " + input_text # SILENT CORRECTION
if input_text.count("Assistant:") == 0:
input_text = input_text + ASSISTANT_PROMPT # SILENT CORRECTION
if input_text[: len("Human:")] == "Human:":
input_text = "\n\n" + input_text
input_text = _add_newlines_before_ha(input_text)
count = 0
# track alternation
for i in range(len(input_text)):
if input_text[i : i + len(HUMAN_PROMPT)] == HUMAN_PROMPT:
if count % 2 == 0:
count += 1
else:
warnings.warn(ALTERNATION_ERROR + f" Received {input_text}")
if input_text[i : i + len(ASSISTANT_PROMPT)] == ASSISTANT_PROMPT:
if count % 2 == 1:
count += 1
else:
warnings.warn(ALTERNATION_ERROR + f" Received {input_text}")
if count % 2 == 1: # Only saw Human, no Assistant
input_text = input_text + ASSISTANT_PROMPT # SILENT CORRECTION
return input_text
[docs]class BedrockBase(BaseModel, ABC):
"""Base class for Bedrock models."""
client: Any = Field(exclude=True) #: :meta private:
region_name: Optional[str] = None
"""The aws region e.g., `us-west-2`. Fallsback to AWS_DEFAULT_REGION env variable
or region specified in ~/.aws/config in case it is not provided here.
"""
credentials_profile_name: Optional[str] = Field(default=None, exclude=True)
"""The name of the profile in the ~/.aws/credentials or ~/.aws/config files, which
has either access keys or role information specified.
If not specified, the default credential profile or, if on an EC2 instance,
credentials from IMDS will be used.
See: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/credentials.html
"""
config: Optional[Config] = None
"""An optional botocore.config.Config instance to pass to the client."""
model_id: str
"""Id of the model to call, e.g., amazon.titan-text-express-v1, this is
equivalent to the modelId property in the list-foundation-models api"""
model_kwargs: Optional[Dict] = None
"""Keyword arguments to pass to the model."""
endpoint_url: Optional[str] = None
"""Needed if you don't want to default to us-east-1 endpoint"""
streaming: bool = False
"""Whether to stream the results."""
provider_stop_sequence_key_name_map: Mapping[str, str] = {
"anthropic": "stop_sequences",
"amazon": "stopSequences",
"ai21": "stop_sequences",
"cohere": "stop_sequences",
}
@root_validator()
def validate_environment(cls, values: Dict) -> Dict:
"""Validate that AWS credentials to and python package exists in environment."""
# Skip creating new client if passed in constructor
if values["client"] is not None:
return values
try:
import boto3
if values["credentials_profile_name"] is not None:
session = boto3.Session(profile_name=values["credentials_profile_name"])
else:
# use default credentials
session = boto3.Session()
values["region_name"] = get_from_dict_or_env(
values,
"region_name",
"AWS_DEFAULT_REGION",
default=session.region_name,
)
client_params = {}
if values["region_name"]:
client_params["region_name"] = values["region_name"]
if values["endpoint_url"]:
client_params["endpoint_url"] = values["endpoint_url"]
if values["config"]:
client_params["config"] = values["config"]
values["client"] = session.client("bedrock-runtime", **client_params)
except ImportError:
raise ModuleNotFoundError(
"Could not import boto3 python package. "
"Please install it with `pip install boto3`."
)
except Exception as e:
raise ValueError(
"Could not load credentials to authenticate with AWS client. "
"Please check that credentials in the specified "
"profile name are valid."
) from e
return values
@property
def _identifying_params(self) -> Mapping[str, Any]:
"""Get the identifying parameters."""
_model_kwargs = self.model_kwargs or {}
return {
**{"model_kwargs": _model_kwargs},
}
def _get_provider(self) -> str:
return self.model_id.split(".")[0]
@property
def _model_is_anthropic(self) -> bool:
return self._get_provider() == "anthropic"
def _prepare_input_and_invoke(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> str:
_model_kwargs = self.model_kwargs or {}
provider = self._get_provider()
params = {**_model_kwargs, **kwargs}
input_body = LLMInputOutputAdapter.prepare_input(provider, prompt, params)
body = json.dumps(input_body)
accept = "application/json"
contentType = "application/json"
try:
response = self.client.invoke_model(
body=body, modelId=self.model_id, accept=accept, contentType=contentType
)
text = LLMInputOutputAdapter.prepare_output(provider, response)
except Exception as e:
raise ValueError(f"Error raised by bedrock service: {e}").with_traceback(
e.__traceback__
)
if stop is not None:
text = enforce_stop_tokens(text, stop)
return text
def _prepare_input_and_invoke_stream(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> Iterator[GenerationChunk]:
_model_kwargs = self.model_kwargs or {}
provider = self._get_provider()
if stop:
if provider not in self.provider_stop_sequence_key_name_map:
raise ValueError(
f"Stop sequence key name for {provider} is not supported."
)
# stop sequence from _generate() overrides
# stop sequences in the class attribute
_model_kwargs[self.provider_stop_sequence_key_name_map.get(provider)] = stop
if provider == "cohere":
_model_kwargs["stream"] = True
params = {**_model_kwargs, **kwargs}
input_body = LLMInputOutputAdapter.prepare_input(provider, prompt, params)
body = json.dumps(input_body)
try:
response = self.client.invoke_model_with_response_stream(
body=body,
modelId=self.model_id,
accept="application/json",
contentType="application/json",
)
except Exception as e:
raise ValueError(f"Error raised by bedrock service: {e}")
for chunk in LLMInputOutputAdapter.prepare_output_stream(
provider, response, stop
):
yield chunk
if run_manager is not None:
run_manager.on_llm_new_token(chunk.text, chunk=chunk)
[docs]class Bedrock(LLM, BedrockBase):
"""Bedrock models.
To authenticate, the AWS client uses the following methods to
automatically load credentials:
https://boto3.amazonaws.com/v1/documentation/api/latest/guide/credentials.html
If a specific credential profile should be used, you must pass
the name of the profile from the ~/.aws/credentials file that is to be used.
Make sure the credentials / roles used have the required policies to
access the Bedrock service.
"""
"""
Example:
.. code-block:: python
from bedrock_langchain.bedrock_llm import BedrockLLM
llm = BedrockLLM(
credentials_profile_name="default",
model_id="amazon.titan-text-express-v1",
streaming=True
)
"""
@property
def _llm_type(self) -> str:
"""Return type of llm."""
return "amazon_bedrock"
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
"""Return whether this model can be serialized by Langchain."""
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "llms", "bedrock"]
@property
def lc_attributes(self) -> Dict[str, Any]:
attributes: Dict[str, Any] = {}
if self.region_name:
attributes["region_name"] = self.region_name
return attributes
class Config:
"""Configuration for this pydantic object."""
extra = Extra.forbid
def _stream(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> Iterator[GenerationChunk]:
"""Call out to Bedrock service with streaming.
Args:
prompt (str): The prompt to pass into the model
stop (Optional[List[str]], optional): Stop sequences. These will
override any stop sequences in the `model_kwargs` attribute.
Defaults to None.
run_manager (Optional[CallbackManagerForLLMRun], optional): Callback
run managers used to process the output. Defaults to None.
Returns:
Iterator[GenerationChunk]: Generator that yields the streamed responses.
Yields:
Iterator[GenerationChunk]: Responses from the model.
"""
return self._prepare_input_and_invoke_stream(
prompt=prompt, stop=stop, run_manager=run_manager, **kwargs
)
def _call(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> str:
"""Call out to Bedrock service model.
Args:
prompt: The prompt to pass into the model.
stop: Optional list of stop words to use when generating.
Returns:
The string generated by the model.
Example:
.. code-block:: python
response = llm("Tell me a joke.")
"""
if self.streaming:
completion = ""
for chunk in self._stream(
prompt=prompt, stop=stop, run_manager=run_manager, **kwargs
):
completion += chunk.text
return completion
return self._prepare_input_and_invoke(prompt=prompt, stop=stop, **kwargs)
[docs] def get_num_tokens(self, text: str) -> int:
if self._model_is_anthropic:
return get_num_tokens_anthropic(text)
else:
return super().get_num_tokens(text)
[docs] def get_token_ids(self, text: str) -> List[int]:
if self._model_is_anthropic:
return get_token_ids_anthropic(text)
else:
return super().get_token_ids(text)