Updating a resource

Use the update-resource command to make updates to an existing resource. This includes resources that weren't originally provisioned using Cloud Control API.

Important

We strongly advice against using Cloud Control API to update resources that are under active management by other services. Doing so can lead to unexpected results. For example, don't use Cloud Control API to update resources that are currently part of an AWS CloudFormation stack.

To update an existing resource, you must specify the resource's identifier. For more information about determining a resource's identifier, see Identifying a resource.

Updating a resource entails changing resource property values. The properties of a resource are defined in its resource type schema. This includes whether the property is required, valid values, and other property constraints. For more information about viewing resource property definitions, see Viewing resource type schemas.

Composing the patch document

To update a resource, you first define the updates as a list of patch operations contained in a JSON patch document. This patch document must adhere to the standard defined in RFC 6902 - JavaScript Object Notation (JSON) Patch.

Each patch operation defines a single update to a specific resource property. The following properties are required:

• op: The operation type. Cloud Control API supports all operations defined in RFC 6902: add, remove, replace, move, copy, and test.

• path: The path to the resource property, relative to the properties section of the resource schema.

Depending on the operation, additional properties may be required. Refer to RFC 6902 for specifics.

When using the update-resource command, you can specify the patch document inline as a string, or specify a file location.

The following example updates the retention policy of an AWS::Logs::LogGroup resource named CloudControlApiLogGroup to 90 days.

aws cloudcontrol update-resource --type-name AWS::Logs::LogGroup --identifier CloudControlApiLogGroup --patch-document '[{"op":"test","path":"RetentionInDays","value":90}]'

How Cloud Control API updates resources

To update a resource, Cloud Control API first retrieves the current state of the resource and then updates the resource in a two-step process:

• Cloud Control API combines the patch operations specified in the update request with the current state of the resource, to generate the desired state of the resource after it's updated. Operations are applied sequentially in the order that they appear in the patch document. Each operation in the sequence is applied to the resource's current state; the resulting resource state becomes the target of the next operation.

  At this point, the entire update request fails if:

  • A patch operation included in the request is invalid.

  • A patch operation of op type test fails.

  In such cases, the entire update request fails and Cloud Control API makes no updates to the resource.

• Cloud Control API then calls the update handler of the resource type to update the resource.

  If the update handler fails at any point, Cloud Control API does not roll back the resource to its previous state.

For example, consider the following patch document that is defined to update an AWS::Logs::LogGroup resource. The document contains two patch operations. The first operation is of type test and checks to see if the resource's retention policy is set to 3653 days. If that is the case, the resource passes the test and Cloud Control API proceeds to the next operation. This operation replaces the current retention policy value with 180 days. If the resource's retention policy is set to a value of other than 3653 days, the first test operation fails and Cloud Control API never runs the second replace operation.

[
  {
    "op": "test",
    "path": "/RetentionInDays",
    "value":3653
  },
  {
    "op": "replace",
    "path": "/RetentionInDays",
    "value":180
  }
]

Tracking the progress of a update resource request

The update-resource command returns a ProgressEvent object that you can use to track the current status of your resource operation request. For more information, see Tracking the progress of resource requests.