def METHOD_NAME(express_route_gateway_name: Optional[str] = None,
                              resource_group_name: Optional[str] = None,
                              opts: Optional[pulumi.InvokeOptions] = None) -> AwaitableGetExpressRouteGatewayResult:
    """
    Fetches the details of a ExpressRoute gateway in a resource group.
    :param str express_route_gateway_name: The name of the ExpressRoute gateway.
    :param str resource_group_name: The name of the resource group.
    """
    __args__ = dict()
    __args__['expressRouteGatewayName'] = express_route_gateway_name
    __args__['resourceGroupName'] = resource_group_name
    opts = pulumi.InvokeOptions.merge(_utilities.get_invoke_opts_defaults(), opts)
    __ret__ = pulumi.runtime.invoke('azure-native:network/v20210301:getExpressRouteGateway', __args__, opts=opts, typ=GetExpressRouteGatewayResult).value
    return AwaitableGetExpressRouteGatewayResult(
        auto_scale_configuration=pulumi.get(__ret__, 'auto_scale_configuration'),
        etag=pulumi.get(__ret__, 'etag'),
        express_route_connections=pulumi.get(__ret__, 'express_route_connections'),
        id=pulumi.get(__ret__, 'id'),
        location=pulumi.get(__ret__, 'location'),
        name=pulumi.get(__ret__, 'name'),
        provisioning_state=pulumi.get(__ret__, 'provisioning_state'),
        tags=pulumi.get(__ret__, 'tags'),
        type=pulumi.get(__ret__, 'type'),
        virtual_hub=pulumi.get(__ret__, 'virtual_hub'))