mypy-boto3-elb Type Stubs for AWS Elastic Load Balancing

1.42.3 · active · verified Sat Apr 11

mypy-boto3-elb provides type annotations for the `boto3` Elastic Load Balancing (ELB) service. It allows static type checkers like MyPy and Pyright to validate `boto3` calls, improving code quality and developer experience. The library version 1.42.3 matches the corresponding `boto3` version, and it's actively maintained with frequent updates reflecting changes in AWS services and `boto3` itself.

Warnings

breaking Support for Python 3.8 was removed in `mypy-boto3-builder` version 8.12.0 (affecting all generated stubs). Users on Python 3.8 must either upgrade Python or pin `mypy-boto3-builder` and generated stubs to an older version.
Fix: Upgrade your Python environment to 3.9 or newer.
breaking TypeDef naming conventions changed in `mypy-boto3-builder` 8.9.0. Specifically, argument TypeDefs may use shorter names (e.g., `CreateDistributionRequestRequestTypeDef` -> `CreateDistributionRequestTypeDef`), and conflicting 'Extra' postfixes moved to the end.
Fix: Update your code to use the new TypeDef names. Refer to the specific service's documentation for exact changes.
gotcha The version of `mypy-boto3-elb` is designed to match the version of `boto3`. For optimal compatibility and correct type inference, it is highly recommended to install `mypy-boto3-elb` (or `boto3-stubs[elb]`) that corresponds to your installed `boto3` version.
Fix: Ensure `pip install mypy-boto3-elb==X.Y.Z` where X.Y.Z matches your `boto3` version, or use `pip install 'boto3-stubs[boto3]'` for synced installation if using the meta-package.
gotcha When using PyCharm, you might experience slow performance with Literal overloads. The maintainers recommend using `boto3-stubs-lite` (e.g., `pip install 'boto3-stubs-lite[elb]'`) or disabling PyCharm's built-in type checker in favor of MyPy or Pyright.
Fix: Consider `boto3-stubs-lite[elb]` for reduced memory footprint or rely on external type checkers.
gotcha Pylint may report 'undefined variable' errors for type-hinted `boto3` clients/resources outside of `TYPE_CHECKING` blocks. To mitigate this, define mock `object` types for the imported symbols outside the `TYPE_CHECKING` block.
Fix: Wrap type imports in `if TYPE_CHECKING:` block and define fallback `object` assignments, as shown in the quickstart example comments.
gotcha All `mypy-boto3` packages migrated to `PEP 561` package format in `mypy-boto3-builder` 8.12.0. While this primarily impacts package structure, ensure your tooling (e.g., custom build systems) is compatible with this standard.
Fix: Verify that your environment correctly handles `py.typed` files and PEP 561 compliant stub packages.

Install

pip install mypy-boto3-elb boto3 mypy Standalone Installation (recommended for specific service)
pip install 'boto3-stubs[elb]' boto3 mypy Installation via boto3-stubs meta-package

Imports

ElasticLoadBalancingClient
```
from mypy_boto3_elb.client import ElasticLoadBalancingClient
```
For type-hinting the ELB client object.
LoadBalancerDescriptionTypeDef
```
from mypy_boto3_elb.type_defs import LoadBalancerDescriptionTypeDef
```
For type-hinting specific dictionary-based response structures.
Paginator
```
from mypy_boto3_elb.paginator import DescribeLoadBalancersPaginator
```
For type-hinting paginator objects specific to ELB operations.

Quickstart

This quickstart demonstrates how to initialize an Elastic Load Balancing (ELB) client with type hints and use it to list classic load balancers. The `TYPE_CHECKING` block ensures that type-related imports are only active during static analysis, preventing runtime overhead. Replace dummy AWS credentials or ensure they are configured in your environment.

import boto3
from typing import TYPE_CHECKING
import os

# Ensure boto3 is configured, e.g., via environment variables or AWS CLI config
# For quickstart, using dummy values if not set in environment
os.environ.setdefault('AWS_ACCESS_KEY_ID', 'YOUR_ACCESS_KEY')
os.environ.setdefault('AWS_SECRET_ACCESS_KEY', 'YOUR_SECRET_KEY')
os.environ.setdefault('AWS_DEFAULT_REGION', 'us-east-1')

if TYPE_CHECKING:
    from mypy_boto3_elb.client import ElasticLoadBalancingClient
    from mypy_boto3_elb.type_defs import LoadBalancerDescriptionTypeDef

def list_classic_load_balancers() -> None:
    """Lists classic load balancers and their DNS names with type hints."""
    # boto3.client automatically infers the return type if mypy-boto3-elb is installed
    client: ElasticLoadBalancingClient = boto3.client("elb")
    
    try:
        response = client.describe_load_balancers()
        load_balancers: list[LoadBalancerDescriptionTypeDef] = response["LoadBalancerDescriptions"]
        
        if not load_balancers:
            print("No classic load balancers found.")
            return

        print("Classic Load Balancers:")
        for lb in load_balancers:
            print(f"  Name: {lb['LoadBalancerName']}")
            print(f"  DNS Name: {lb['DNSName']}")
            print(f"  Scheme: {lb.get('Scheme', 'internet-facing')}") # 'Scheme' might be optional
    except Exception as e:
        print(f"Error describing load balancers: {e}")

if __name__ == "__main__":
    list_classic_load_balancers()

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