Type annotations for boto3 Lambda

1.42.85 · active · verified Sat Apr 11

Type annotations for boto3 Lambda 1.42.85 service generated with mypy-boto3-builder 8.12.0. This library provides static type checking for AWS Boto3's Lambda client, improving code quality, autocomplete, and error detection in IDEs and with type checkers like Mypy and Pyright. It is part of the `types-boto3` ecosystem, which aims to provide comprehensive type stubs for all Boto3 services. The library typically releases new versions in sync with `boto3` releases.

Warnings

breaking Support for Python 3.8 has been removed in `mypy-boto3-builder` version 8.12.0 and consequently for all generated `types-boto3` packages, including `types-boto3-lambda`.
Fix: Upgrade your Python environment to 3.9 or newer.
breaking TypeDef naming conventions changed in `mypy-boto3-builder` version 8.9.0. TypeDefs for packed method arguments now use shorter names (e.g., `CreateDistributionRequestRequestTypeDef` became `CreateDistributionRequestTypeDef`).
Fix: Review and update your TypeDef import paths and names to match the new, shorter conventions.
gotcha When using `boto3-stubs-lite[lambda]` or `mypy-boto3-lambda` (standalone package), explicit type annotations are often required for `boto3.client` calls to enable full type inference. Without them, IDEs and type checkers might not provide complete suggestions or checks.
Fix: Always explicitly type annotate your client instances: `client: LambdaClient = boto3.client('lambda')`.
gotcha PyCharm can experience performance issues with `Literal` overloads in `types-boto3` packages, leading to high CPU usage.
Fix: Consider using `boto3-stubs-lite` packages (e.g., `boto3-stubs-lite[lambda]`), disabling PyCharm's built-in type checker in favor of `mypy` or `pyright`, or using explicit type annotations where possible.
gotcha To avoid `types-boto3-lambda` being a runtime dependency in production code, it is recommended to wrap type imports within a `typing.TYPE_CHECKING` block.
Fix: Use `from typing import TYPE_CHECKING; if TYPE_CHECKING: from mypy_boto3_lambda.client import LambdaClient`.

Install

pip install 'boto3-stubs[lambda]' Recommended installation with boto3-stubs
pip install mypy-boto3-lambda Standalone package installation

Imports

LambdaClient
```
from mypy_boto3_lambda.client import LambdaClient
```
While `boto3.client('lambda')` returns a client, without the explicit import and type annotation, IDEs and type checkers cannot provide full autocompletion or type checking for the client's methods and return values.
InvokeFunctionResponseTypeDef
```
from mypy_boto3_lambda.type_defs import InvokeFunctionResponseTypeDef
```
Used for type-hinting the responses from Lambda client methods.
RuntimeType
```
from mypy_boto3_lambda.literals import RuntimeType
```
Used for type-hinting literal values, such as Lambda runtime types.

Quickstart

This quickstart demonstrates how to obtain a type-hinted AWS Lambda client and invoke a function. It includes the necessary `TYPE_CHECKING` guard to ensure the type stubs are only used during static analysis, avoiding a runtime dependency. The function name is retrieved from an environment variable for reusability.

import boto3
import os
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from mypy_boto3_lambda.client import LambdaClient
    from mypy_boto3_lambda.type_defs import InvokeFunctionResponseTypeDef

def get_lambda_client() -> "LambdaClient":
    """Returns a typed Lambda client."""
    return boto3.client("lambda")

def invoke_my_lambda(client: "LambdaClient", function_name: str, payload: dict) -> "InvokeFunctionResponseTypeDef":
    """Invokes a Lambda function with type hints."""
    response = client.invoke(
        FunctionName=function_name,
        InvocationType='RequestResponse',
        Payload=bytes(str(payload).encode('utf-8'))
    )
    return response

# Example Usage
if __name__ == "__main__":
    lambda_client = get_lambda_client()
    # Use os.environ.get for dynamic configuration in runnable examples
    function_name = os.environ.get('LAMBDA_FUNCTION_NAME', 'my-test-lambda-function')
    example_payload = {"greeting": "hello from types-boto3-lambda"}

    try:
        print(f"Invoking Lambda function: {function_name}")
        response = invoke_my_lambda(lambda_client, function_name, example_payload)
        print(f"Lambda Invocation Status Code: {response.get('StatusCode')}")
        # If the Lambda returns a JSON payload, you might want to read and decode it
        # payload_stream = response.get('Payload')
        # if payload_stream:
        #     payload_data = payload_stream.read().decode('utf-8')
        #     print(f"Lambda Response Payload: {payload_data}")
    except Exception as e:
        print(f"Error invoking Lambda: {e}")

view raw JSON →