No boto3.client handy? Need to catch a boto3 exception? Build the exceptions via two obscure methods!

build_exceptions_full.py

from typing import Optional

from boto3 import Session
from botocore import UNSIGNED
from botocore.config import Config
from mypy_boto3_servicecatalog.literals import ServiceName


def build_service_exceptions(
    service_name: ServiceName, *, session: Optional[Session] = None
):
    """
    Build a ClientExceptions for the given service name.
    """
    if not session:
        session = Session()

    return session.client(
        service_name,
        # Skip the normal credential provider chain by telling the client to
        # use unsigned requests. Without this, the client will attempt to
        # use the default credential provider chain, which results in a
        # process of trying to connect to various link-local endpoints.
        config=Config(signature_version=UNSIGNED)
    ).exceptions

build_exceptions_raw.py

from typing import Optional

from botocore.configprovider import (
    ConfigValueStore,
    create_botocore_default_config_mapping,
)
from botocore.errorfactory import ClientExceptionsFactory
from botocore.loaders import create_loader
from botocore.model import ServiceModel
from botocore.session import Session
from mypy_boto3_servicecatalog.literals import ServiceName


# Includes a cache for the exceptions by service.
exception_factory = ClientExceptionsFactory()


def build_service_exceptions(service_name: ServiceName, *, session: Optional[Session] = None):
    """
    Build a ClientExceptions for the given service name.
    """
    config_store = ConfigValueStore(
        create_botocore_default_config_mapping(session or Session())
    )
    data_loader = create_loader(config_store.get_config_variable("data_path"))
    service_model = ServiceModel(
        data_loader.load_service_model(
            service_name=service_name, type_name="service-2", api_version=None
        ),
        service_name=service_name,
    )
    return exception_factory.create_client_exceptions(service_model)