Type annotations for boto3 EMR

Warnings

• breaking Support for Python 3.8 has been removed in `mypy-boto3-builder` version 8.12.0. Users on Python 3.8 will need to upgrade to Python 3.9 or newer to use the latest stub packages.
  Fix: Upgrade your Python environment to 3.9 or newer. If you must use Python 3.8, you will be limited to older versions of `mypy-boto3-emr`.
• breaking TypeDef naming conventions changed significantly in `mypy-boto3-builder` version 8.9.0. Specifically, redundant 'Request' suffixes were removed (e.g., `CreateDistributionRequestRequestTypeDef` became `CreateDistributionRequestTypeDef`), and 'Extra' postfixes moved to the end of the name. This may break explicit imports of TypeDefs.
  Fix: Review your code for explicit imports of `_type_defs` and adjust the `TypeDef` names according to the new conventions.
• gotcha `mypy-boto3-emr` provides *only* type stubs for the EMR service. It does not include the runtime `boto3` library itself. For your code to run, `boto3` must be installed separately.
  Fix: Ensure `boto3` is installed alongside `mypy-boto3-emr` (e.g., `pip install boto3 mypy-boto3-emr`).
• gotcha AWS service names can change or be deprecated over time (e.g., `sms-voice` was replaced by `pinpoint-sms-voice` in builder 8.11.0). This means the corresponding `mypy-boto3` stub package names might also change or be removed. Always consult the latest `boto3` and `mypy-boto3` documentation for current service names.
  Fix: Stay updated with `boto3` and `mypy-boto3` releases. If a service name changes, update your `boto3.client()` calls and install the correct `mypy-boto3-servicename` package.

Install

• pip install mypy-boto3-emr Install the EMR stubs
• pip install boto3 mypy Install runtime and type checker

Imports

• EMRClient

  from mypy_boto3_emr.client import EMRClient

  Import the typed client object for explicit type hints.
• ListClustersOutputTypeDef

  from mypy_boto3_emr.type_defs import ListClustersOutputTypeDef

  Import specific TypeDef objects for precise typing of API responses or request parameters.

Quickstart

This quickstart demonstrates how to use `mypy-boto3-emr` to add type hints to your boto3 EMR client and API responses. The `TYPE_CHECKING` block ensures that stub imports are only processed by the type checker, avoiding runtime import errors if the stubs are not installed. Explicitly typing the client and response objects allows MyPy to provide comprehensive checks.

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

# Conditional import for type checking only
if TYPE_CHECKING:
    from mypy_boto3_emr.client import EMRClient
    from mypy_boto3_emr.type_defs import ListClustersOutputTypeDef, ClusterSummaryTypeDef

# Example function using type hints
def get_running_emr_clusters() -> List[ClusterSummaryTypeDef]:
    # The client variable is explicitly typed for MyPy
    client: EMRClient = boto3.client(
        "emr",
        region_name=os.environ.get('AWS_REGION', 'us-east-1'),
        aws_access_key_id=os.environ.get('AWS_ACCESS_KEY_ID', 'DUMMY_KEY'),
        aws_secret_access_key=os.environ.get('AWS_SECRET_ACCESS_KEY', 'DUMMY_SECRET')
    )

    # The response variable is explicitly typed
    response: ListClustersOutputTypeDef = client.list_clusters(ClusterStates=['RUNNING'])

    clusters: List[ClusterSummaryTypeDef] = response.get('Clusters', [])
    print(f"Found {len(clusters)} running EMR clusters.")
    for cluster in clusters:
        print(f"  - Cluster ID: {cluster['Id']}, Name: {cluster['Name']}")
    return clusters

if __name__ == "__main__":
    # This code will run, but type hints are only checked by MyPy
    get_running_emr_clusters()