def METHOD_NAME(name: Optional[str] = None,
                                  resource_group_name: Optional[str] = None,
                                  resource_name: Optional[str] = None,
                                  opts: Optional[pulumi.InvokeOptions] = None) -> AwaitableGetWebPubSubCustomDomainResult:
    """
    Get a custom domain.
    Azure REST API version: 2023-02-01.
    :param str name: Custom domain name.
    :param str resource_group_name: The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
    :param str resource_name: The name of the resource.
    """
    __args__ = dict()
    __args__['name'] = name
    __args__['resourceGroupName'] = resource_group_name
    __args__['resourceName'] = resource_name
    opts = pulumi.InvokeOptions.merge(_utilities.get_invoke_opts_defaults(), opts)
    __ret__ = pulumi.runtime.invoke('azure-native:webpubsub:getWebPubSubCustomDomain', __args__, opts=opts, typ=GetWebPubSubCustomDomainResult).value
    return AwaitableGetWebPubSubCustomDomainResult(
        custom_certificate=pulumi.get(__ret__, 'custom_certificate'),
        domain_name=pulumi.get(__ret__, 'domain_name'),
        id=pulumi.get(__ret__, 'id'),
        name=pulumi.get(__ret__, 'name'),
        provisioning_state=pulumi.get(__ret__, 'provisioning_state'),
        system_data=pulumi.get(__ret__, 'system_data'),
        type=pulumi.get(__ret__, 'type'))