mypy-boto3-greengrass Type Stubs

Warnings

• breaking Support for Python 3.8 has been removed in `mypy-boto3-builder` version 8.12.0, affecting all generated `mypy-boto3-*` packages, including `mypy-boto3-greengrass`.
  Fix: Upgrade your Python environment to 3.9 or newer.
• breaking TypeDef naming conventions changed in `mypy-boto3-builder` 8.9.0. Specifically, packed method arguments use shorter names (e.g., `CreateDistributionRequestRequestTypeDef` -> `CreateDistributionRequestTypeDef`), and conflicting `Extra` postfixes are moved to the end.
  Fix: Review your code for explicit imports or uses of `TypeDef` names and adjust them according to the new conventions.
• gotcha `mypy-boto3-greengrass` provides only type annotations; `boto3` itself is a separate runtime dependency and must be installed alongside these stubs for your application to function.
  Fix: Ensure `pip install boto3` is executed in your environment.
• gotcha To benefit from these type stubs, a static type checker like `mypy` or `pyright` must be installed and configured in your development environment.
  Fix: Install `mypy` (`pip install mypy`) and integrate it into your CI/CD pipeline or IDE.
• gotcha It is generally recommended that the major.minor version of `mypy-boto3-greengrass` matches the major.minor version of your installed `boto3` library for optimal compatibility and accuracy of type hints.
  Fix: When updating `boto3`, also update `mypy-boto3-greengrass` to a compatible version.
• gotcha For production deployments, consider using `if TYPE_CHECKING:` blocks for importing `mypy-boto3-*` modules to avoid adding `mypy-boto3-greengrass` as a runtime dependency. Some linters like `pylint` might complain about undefined variables without additional `else: ClientType = object` blocks.
  Fix: Wrap type stub imports in `if TYPE_CHECKING:` blocks and, if using `pylint`, add `else` branches assigning `object` to client types.

Install

• pip install boto3 mypy mypy-boto3-greengrass Install Boto3, Mypy, and Greengrass Stubs
• pip install 'boto3-stubs[greengrass]' mypy Alternative: Install Boto3 Stubs with Greengrass Extra

Imports

• GreengrassClient

  from mypy_boto3_greengrass.client import GreengrassClient

  Type hint for the Greengrass service client.
• GetCoreDefinitionResponseTypeDef

  from mypy_boto3_greengrass.type_defs import GetCoreDefinitionResponseTypeDef

  Type hint for the response dictionary of Greengrass operations. Full list of TypeDefs available in documentation.
• GreengrassServiceResource

  from mypy_boto3_greengrass.service_resource import GreengrassServiceResource

  Type hint for the Greengrass service resource (if applicable for the service).

Quickstart

This quickstart demonstrates how to use `mypy-boto3-greengrass` for type hinting your `boto3` Greengrass client. It highlights the use of `TYPE_CHECKING` for conditional imports, ensuring the stubs are only used during static analysis. When `mypy` processes this code, it uses `GreengrassClient` and `GetCoreDefinitionResponseTypeDef` to validate client methods and response structures. At runtime, the standard `boto3` client is used.

import boto3
import os
from typing import TYPE_CHECKING, Dict, Any

# Conditional import for type checking only to avoid runtime dependency
# if mypy-boto3-greengrass is not installed in production environments.
if TYPE_CHECKING:
    from mypy_boto3_greengrass.client import GreengrassClient
    from mypy_boto3_greengrass.type_defs import GetCoreDefinitionResponseTypeDef

def get_core_definition_name(core_definition_id: str) -> str:
    """
    Retrieves the name of a Greengrass core definition using type-hinted boto3.
    Type annotations ensure static analysis correctness.
    """
    # Initialize boto3 client. mypy-boto3 provides stubs for its methods.
    client = boto3.client("greengrass", region_name=os.environ.get("AWS_REGION", "us-east-1"))

    # Asserting the client type for static analysis with mypy.
    # At runtime, 'client' is a regular boto3 client.
    if TYPE_CHECKING:
        greengrass_client: GreengrassClient = client
        response: GetCoreDefinitionResponseTypeDef = greengrass_client.get_core_definition(
            CoreDefinitionId=core_definition_id
        )
    else:
        # Runtime execution uses the actual boto3 client without explicit type assertion.
        # This branch is taken if TYPE_CHECKING is False (e.g., in production).
        response = client.get_core_definition(CoreDefinitionId=core_definition_id)
    
    # Mypy will now correctly check access to 'Name' and its type
    return response['Name']

if __name__ == "__main__":
    # For this to make actual AWS calls, ensure AWS_ACCESS_KEY_ID,
    # AWS_SECRET_ACCESS_KEY (and optionally AWS_REGION) are set in your environment.
    # Otherwise, it will attempt a call that might fail with an AWS error.

    print("Note: This example requires AWS credentials for live execution.")
    print("   To run 'mypy' on this file, ensure 'mypy boto3 mypy-boto3-greengrass' are installed.")
    print("   Example: 'mypy your_script_name.py'")

    example_core_id = "your-greengrass-core-definition-id"

    if os.environ.get("AWS_ACCESS_KEY_ID") and os.environ.get("AWS_SECRET_ACCESS_KEY"):
        print(f"\nAttempting to get Greengrass Core Definition name for ID: {example_core_id}")
        try:
            core_name = get_core_definition_name(example_core_id)
            print(f"Retrieved Core Definition Name: {core_name}")
        except Exception as e:
            print(f"An error occurred during AWS call: {e}")
            print("Please ensure the Core Definition ID is valid and credentials are correct.")
    else:
        print("\nAWS credentials not found. Skipping live AWS call.")
        print("To test type-checking, you can run 'mypy' on this file without credentials.")