import asyncio
import json
import warnings
from abc import ABC
from typing import (
Any,
AsyncGenerator,
AsyncIterator,
Dict,
Iterator,
List,
Mapping,
Optional,
Tuple,
)
from langchain_core._api.deprecation import deprecated
from langchain_core.callbacks import (
AsyncCallbackManagerForLLMRun,
CallbackManagerForLLMRun,
)
from langchain_core.language_models.llms import LLM
from langchain_core.outputs import GenerationChunk
from langchain_core.utils import get_from_dict_or_env, pre_init
from pydantic import BaseModel, ConfigDict, Field
from langchain_community.llms.utils import enforce_stop_tokens
from langchain_community.utilities.anthropic import (
get_num_tokens_anthropic,
get_token_ids_anthropic,
)
AMAZON_BEDROCK_TRACE_KEY = "amazon-bedrock-trace"
GUARDRAILS_BODY_KEY = "amazon-bedrock-guardrailAssessment"
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
def _stream_response_to_generation_chunk(
stream_response: Dict[str, Any],
) -> GenerationChunk:
"""Convert a stream response to a generation chunk."""
if not stream_response["delta"]:
return GenerationChunk(text="")
return GenerationChunk(
text=stream_response["delta"]["text"],
generation_info=dict(
finish_reason=stream_response.get("stop_reason", None),
),
)
[docs]
class BedrockBase(BaseModel, ABC):
"""Base class for Bedrock models."""
model_config = ConfigDict(protected_namespaces=())
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: Any = None
"""An optional botocore.config.Config instance to pass to the client."""
provider: Optional[str] = None
"""The model provider, e.g., amazon, cohere, ai21, etc. When not supplied, provider
is extracted from the first part of the model_id e.g. 'amazon' in
'amazon.titan-text-express-v1'. This value should be provided for model ids that do
not have the provider in them, e.g., custom and provisioned models that have an ARN
associated with them."""
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. For custom and
provisioned models, an ARN value is expected."""
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",
"mistral": "stop",
}
guardrails: Optional[Mapping[str, Any]] = {
"id": None,
"version": None,
"trace": False,
}
"""
An optional dictionary to configure guardrails for Bedrock.
This field 'guardrails' consists of two keys: 'id' and 'version',
which should be strings, but are initialized to None. It's used to
determine if specific guardrails are enabled and properly set.
Type:
Optional[Mapping[str, str]]: A mapping with 'id' and 'version' keys.
Example:
llm = Bedrock(model_id="<model_id>", client=<bedrock_client>,
model_kwargs={},
guardrails={
"id": "<guardrail_id>",
"version": "<guardrail_version>"})
To enable tracing for guardrails, set the 'trace' key to True and pass a callback handler to the
'run_manager' parameter of the 'generate', '_call' methods.
Example:
llm = Bedrock(model_id="<model_id>", client=<bedrock_client>,
model_kwargs={},
guardrails={
"id": "<guardrail_id>",
"version": "<guardrail_version>",
"trace": True},
callbacks=[BedrockAsyncCallbackHandler()])
[https://python.langchain.com/docs/modules/callbacks/] for more information on callback handlers.
class BedrockAsyncCallbackHandler(AsyncCallbackHandler):
async def on_llm_error(
self,
error: BaseException,
**kwargs: Any,
) -> Any:
reason = kwargs.get("reason")
if reason == "GUARDRAIL_INTERVENED":
...Logic to handle guardrail intervention...
""" # noqa: E501
[docs]
@pre_init
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.get("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 ImportError(
"Could not import boto3 python package. "
"Please install it with `pip install boto3`."
)
except ValueError as e:
raise ValueError(f"Error raised by bedrock service: {e}")
except Exception as e:
raise ValueError(
"Could not load credentials to authenticate with AWS client. "
"Please check that credentials in the specified "
f"profile name are valid. Bedrock error: {e}"
) 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:
if self.provider:
return self.provider
if self.model_id.startswith("arn"):
raise ValueError(
"Model provider should be supplied when passing a model ARN as "
"model_id"
)
return self.model_id.split(".")[0]
@property
def _model_is_anthropic(self) -> bool:
return self._get_provider() == "anthropic"
@property
def _guardrails_enabled(self) -> bool:
"""
Determines if guardrails are enabled and correctly configured.
Checks if 'guardrails' is a dictionary with non-empty 'id' and 'version' keys.
Checks if 'guardrails.trace' is true.
Returns:
bool: True if guardrails are correctly configured, False otherwise.
Raises:
TypeError: If 'guardrails' lacks 'id' or 'version' keys.
"""
try:
return (
isinstance(self.guardrails, dict)
and bool(self.guardrails["id"])
and bool(self.guardrails["version"])
)
except KeyError as e:
raise TypeError(
"Guardrails must be a dictionary with 'id' and 'version' keys."
) from e
def _get_guardrails_canonical(self) -> Dict[str, Any]:
"""
The canonical way to pass in guardrails to the bedrock service
adheres to the following format:
"amazon-bedrock-guardrailDetails": {
"guardrailId": "string",
"guardrailVersion": "string"
}
"""
return {
"amazon-bedrock-guardrailDetails": {
"guardrailId": self.guardrails.get("id"), # type: ignore[union-attr]
"guardrailVersion": self.guardrails.get("version"), # type: ignore[union-attr]
}
}
def _prepare_input_and_invoke(
self,
prompt: Optional[str] = None,
system: Optional[str] = None,
messages: Optional[List[Dict]] = None,
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> Tuple[str, Dict[str, Any]]:
_model_kwargs = self.model_kwargs or {}
provider = self._get_provider()
params = {**_model_kwargs, **kwargs}
if self._guardrails_enabled:
params.update(self._get_guardrails_canonical())
input_body = LLMInputOutputAdapter.prepare_input(
provider=provider,
model_kwargs=params,
prompt=prompt,
system=system,
messages=messages,
)
body = json.dumps(input_body)
accept = "application/json"
contentType = "application/json"
request_options = {
"body": body,
"modelId": self.model_id,
"accept": accept,
"contentType": contentType,
}
if self._guardrails_enabled:
request_options["guardrail"] = "ENABLED"
if self.guardrails.get("trace"): # type: ignore[union-attr]
request_options["trace"] = "ENABLED"
try:
response = self.client.invoke_model(**request_options)
text, body, usage_info = LLMInputOutputAdapter.prepare_output(
provider, response
).values()
except Exception as e:
raise ValueError(f"Error raised by bedrock service: {e}")
if stop is not None:
text = enforce_stop_tokens(text, stop)
# Verify and raise a callback error if any intervention occurs or a signal is
# sent from a Bedrock service,
# such as when guardrails are triggered.
services_trace = self._get_bedrock_services_signal(body) # type: ignore[arg-type]
if services_trace.get("signal") and run_manager is not None:
run_manager.on_llm_error(
Exception(
f"Error raised by bedrock service: {services_trace.get('reason')}"
),
**services_trace,
)
return text, usage_info
def _get_bedrock_services_signal(self, body: dict) -> dict:
"""
This function checks the response body for an interrupt flag or message that indicates
whether any of the Bedrock services have intervened in the processing flow. It is
primarily used to identify modifications or interruptions imposed by these services
during the request-response cycle with a Large Language Model (LLM).
""" # noqa: E501
if (
self._guardrails_enabled
and self.guardrails.get("trace") # type: ignore[union-attr]
and self._is_guardrails_intervention(body)
):
return {
"signal": True,
"reason": "GUARDRAIL_INTERVENED",
"trace": body.get(AMAZON_BEDROCK_TRACE_KEY),
}
return {
"signal": False,
"reason": None,
"trace": None,
}
def _is_guardrails_intervention(self, body: dict) -> bool:
return body.get(GUARDRAILS_BODY_KEY) == "GUARDRAIL_INTERVENED"
def _prepare_input_and_invoke_stream(
self,
prompt: Optional[str] = None,
system: Optional[str] = None,
messages: Optional[List[Dict]] = None,
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}
if self._guardrails_enabled:
params.update(self._get_guardrails_canonical())
input_body = LLMInputOutputAdapter.prepare_input(
provider=provider,
prompt=prompt,
system=system,
messages=messages,
model_kwargs=params,
)
body = json.dumps(input_body)
request_options = {
"body": body,
"modelId": self.model_id,
"accept": "application/json",
"contentType": "application/json",
}
if self._guardrails_enabled:
request_options["guardrail"] = "ENABLED"
if self.guardrails.get("trace"): # type: ignore[union-attr]
request_options["trace"] = "ENABLED"
try:
response = self.client.invoke_model_with_response_stream(**request_options)
except Exception as e:
raise ValueError(f"Error raised by bedrock service: {e}")
for chunk in LLMInputOutputAdapter.prepare_output_stream(
provider, response, stop, True if messages else False
):
# verify and raise callback error if any middleware intervened
self._get_bedrock_services_signal(chunk.generation_info) # type: ignore[arg-type]
if run_manager is not None:
run_manager.on_llm_new_token(chunk.text, chunk=chunk)
yield chunk
async def _aprepare_input_and_invoke_stream(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> AsyncIterator[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."
)
_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=provider, prompt=prompt, model_kwargs=params
)
body = json.dumps(input_body)
response = await asyncio.get_running_loop().run_in_executor(
None,
lambda: self.client.invoke_model_with_response_stream(
body=body,
modelId=self.model_id,
accept="application/json",
contentType="application/json",
),
)
async for chunk in LLMInputOutputAdapter.aprepare_output_stream(
provider, response, stop
):
if run_manager is not None and asyncio.iscoroutinefunction(
run_manager.on_llm_new_token
):
await run_manager.on_llm_new_token(chunk.text, chunk=chunk)
elif run_manager is not None:
run_manager.on_llm_new_token(chunk.text, chunk=chunk) # type: ignore[unused-coroutine]
yield chunk
[docs]
@deprecated(
since="0.0.34", removal="1.0", alternative_import="langchain_aws.BedrockLLM"
)
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
)
"""
[docs]
@pre_init
def validate_environment(cls, values: Dict) -> Dict:
model_id = values["model_id"]
if model_id.startswith("anthropic.claude-3"):
raise ValueError(
"Claude v3 models are not supported by this LLM."
"Please use `from langchain_community.chat_models import BedrockChat` "
"instead."
)
return super().validate_environment(values)
@property
def _llm_type(self) -> str:
"""Return type of llm."""
return "amazon_bedrock"
@classmethod
def is_lc_serializable(cls) -> bool:
"""Return whether this model can be serialized by Langchain."""
return True
@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
model_config = ConfigDict(
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.invoke("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
text, _ = self._prepare_input_and_invoke(
prompt=prompt, stop=stop, run_manager=run_manager, **kwargs
)
return text
async def _astream(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> AsyncGenerator[GenerationChunk, None]:
"""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.
Yields:
AsyncGenerator[GenerationChunk, None]: Generator that asynchronously yields
the streamed responses.
"""
async for chunk in self._aprepare_input_and_invoke_stream(
prompt=prompt, stop=stop, run_manager=run_manager, **kwargs
):
yield chunk
async def _acall(
self,
prompt: str,
stop: Optional[List[str]] = None,
run_manager: Optional[AsyncCallbackManagerForLLMRun] = 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 = await llm._acall("Tell me a joke.")
"""
if not self.streaming:
raise ValueError("Streaming must be set to True for async operations. ")
chunks = [
chunk.text
async for chunk in self._astream(
prompt=prompt, stop=stop, run_manager=run_manager, **kwargs
)
]
return "".join(chunks)
[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)
