# Updating an Amazon Cloud Map service instance
<a name="updating-instances"></a>

You can update service instances in two ways, depending on which values you want to update:
+ **Update any values**: If you want to update any of the values that you specified for a service instance when you registered it, including custom attributes, you need to reregister the service instance and respecify all values. Follow the steps in [Registering a resource as an Amazon Cloud Map service instance](registering-instances.md), specifying the instance ID of the existing service instance for **Service instance ID**.

  Alternatively, you can use the [https://docs.amazonaws.cn/cloud-map/latest/api/API_RegisterInstance.html](https://docs.amazonaws.cn/cloud-map/latest/api/API_RegisterInstance.html) API. You can specify the ID of the existing instance and service using the `InstanceId` and `ServiceId` parameters and respecify other values.
+ **Update only custom attributes**: If you want to update only the custom attributes for a service instance, you don't need to reregister the instance. You can update only those values. See [Updating the custom attributes for a service instance](#updating-instance-attributes-procedure).

## Updating the custom attributes for a service instance
<a name="updating-instance-attributes-procedure"></a>

**To update only custom attributes for a service instance**

1. Sign in to the Amazon Web Services Management Console and open the Amazon Cloud Map console at [https://console.amazonaws.cn/cloudmap/](https://console.amazonaws.cn/cloudmap/).

1. In the navigation pane, choose **Namespaces**.

1. On the **Namespaces** page, choose the namespace that contains the service that you originally used to register the service instance.

1. On the **Namespace: {{namespace-name}}** page, choose the service that you used to register the service instance.

1. On the **Service: {{service-name}}** page, choose the name of the service instance that you want to update.

1. In the **Custom attributes** section, choose **Edit**.

1. On the **Edit service instance: {{instance-name}}** page, add, remove, or update custom attributes. You can update both keys and values for existing attributes.

1. Choose **Update service instance**.