Use dynamic variables in your workflow document

You can use dynamic variables in your workflow documents to represent values that vary at runtime for your image creation process. Dynamic variable values are represented as JSONPath selectors with structural nodes that uniquely identify the target variable.

JSONPath dynamic workflow variable structure

$.<document structure>.[<step name>].<variable name>

The first node after the root ($) refers to the workflow document structure, such as stepOutputs, or in the case of Image Builder system variables, imageBuilder. The following list contains supported JSONPath workflow document structure nodes.

Document structure nodes

• parameters - The workflow parameters

• stepOutputs - Outputs from a step in the same workflow doc

• workflowOutputs - Outputs from a workflow doc that already ran

• imagebuilder - Image Builder system variables

The parameters and stepOutputs document structure nodes include an optional node for the step name. This helps ensure unique variable names across all of the steps.

The final node in the JSONPath is the name of the target variable, such as instanceId.

Each step can refer to the output of any prior step actions with these JSONPath dynamic variables. This is also known as chaining, or referencing. To refer to output from a prior step action, you might use the following dynamic variable.

$.stepOutputs.step-name.output-name

Example

  - name: ApplyTestComponents
    action: ExecuteComponents
    onFailure: Abort
    inputs:
      instanceId.$: "$.stepOutputs.LaunchTestInstance.instanceId"

Use Image Builder system variables

Image Builder provides the following system variables that you can use in your workflow document:

Variable name	Description	Type	Example value
cloudWatchLogGroup	The name of the CloudWatch Logs group for output logs. Format: /aws/imagebuilder/<recipe-name>	String	/aws/imagebuilder/sampleImageRecipe
cloudWatchLogStream	The name of the CloudWatch Logs stream for output logs.	String	1.0.0/1
collectImageMetadata	The setting that directs Image Builder whether to collect instance metadata.	Boolean	true | false
collectImageScanFindings	The current value of the setting that enables Image Builder to collect image scan findings.	Boolean	true | false
imageBuildNumber	The build version number of the image.	Integer	1
imageId	The AMI id of the base image.	String	ami-1234567890abcdef1
imageName	The name of the image.	String	sampleImage
imageType	The image output type.	String	AMI | Docker
imageVersionNumber	The version number of the image.	String	1.0.0
instanceProfileName	The name of the instance profile role that Image Builder uses to launch build and test instances.	String	SampleImageBuilderInstanceProfileRole
platform	The operating system platform of the image that's built.	String	Linux | Windows | MacOS
s3Logs	A JSON object that contains configuration for the S3 logs that Image Builder writes.	JSON object	{'s3Logs': {'s3BucketName': 'sample-bucket', 's3KeyPrefix': 'ib-logs'}}
securityGroups	The security group IDs that apply to build and test instances.	List [String]	[sg-1234567890abcdef1, sg-11112222333344445]
sourceImageARN	The Amazon Resource Name (ARN) of the Image Builder image resource that the workflow uses for build and test stages.	String	arn:aws:imagebuilder:us-east-1:111122223333:image/sampleImage/1.0.0/1
subnetId	The ID of the subnet to launch the build and test instances into.	String	subnet-1234567890abcdef1
terminateInstanceOnFailure	The current value of the setting that directs Image Builder to terminate the instance on failure or keep it for troubleshooting.	Boolean	true | false
workflowPhase	The current stage that's running for the workflow execution.	String	Build | Test
workingDirectory	The path to the working directory.	String	/tmp