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Sequential Resource Processing

In various cases, some resources depend on other resources to already exist in order to process. Whenever an order of resource processing is necessary, the processed-after attribute can be utilized.

This attribute contains a list of resource names. It creates a sequence of services, an order, in which the services should be processed. If a resource has this attribute, it will be processed after the other resources in a higher position are processed.

Note:

If the parameter processed-after is not specified, the resources are processed in parallel.

Note:

The processed-after parameter is supported from schema version 3 onwards. If you attempt to use processed-after with schema version lower than 3, the deployment will ignore the attribute.

Example: Service A requires service B and service C to be processed first. On the other hand, both service B and service C require service D to be processed first. Service D does not require any other service to be proccessed. So the sequence for processing is - D → B, C → A.

Sample Code:

MTA Deployment Descriptor (mtad.yaml) 

 

_schema-version: 3 

ID: multiple-anatz 

version: 3.0.0 

 

modules: 

  - name: multiple-anatz 

    type: staticfile 

resources: 

  - name: serviceA 

    type: org.cloudfoundry.managed-service 

    parameters: 

      service: application-logs 

      service-plan: lite 

    processed-after: [ serviceB, serviceC ] 

 

  - name: serviceB 

    type: org.cloudfoundry.managed-service 

    parameters: 

      service: application-logs 

      service-plan: lite 

    processed-after: [ serviceD ] 

 

  - name: serviceC 

    type: org.cloudfoundry.managed-service 

    parameters: 

      service: application-logs 

      service-plan: lite 

    processed-after: [ serviceD ]         

 

  - name: serviceD 

    type: org.cloudfoundry.managed-service 

    parameters: 

      service: application-logs    

      service-plan: lite

In the example, the processed-after attribute ensures that serviceD is processed first, then serviceC and serviceB are processed in parallel, and finally serviceA is processed.

Circular Dependencies

Due to a modelling error, you can create direct or transitive circular deployment order dependencies between resources. In such cases, it is reported as a deployment error.