Product Documentation

Repeat construct

You can use the repeat construct of a component to build multiple configuration objects of the same type.

In the following example, the members-svcg-comp component is used to bind the list of services to the service group created by the parent component. In order to create a configuration object that binds each server to the service group, use the repeat construct to iterate over the list of services specified for the parameter svc-servers. During the iteration, the component creates a NITRO object of type servicegroup_servicegroupmember_binding for each service (referred to as srv in the repeat-item construct) in the service group, and it sets the ip attribute in each NITRO object to the IP address of the corresponding service.

Example:

components:
  -
      name: my-lbvserver-comp
      type: ns::lbvserver
      properties:
           name: $parameters.name + "-lb"
           servicetype: HTTP
           ipv46: $parameters.ip
           port: 80
           lbmethod: $parameters.lb-alg
          components:
                -
                   name: my-svcg-comp
                   type: ns::servicegroup
                   properties:
                        name: $parameters.name + "-svcgrp"
                        servicetype: HTTP
                  components:
                         -
                         name: lbvserver-svg-binding-comp
                         type: ns::lbvserver\servicegroup\binding
                         properties:
                               name: $parent.parent.properties.name
                               servicegroupname: $parent.properties.name
                         -
                         name: members-svcg-comp
                         type: ns::servicegroup\servicegroupmember\binding
                         repeat:
                           repeat-list: $parameters.svc-servers
                           repeat-item: srv
                         properties:
                                ip: $srv
                                port: $parameters.svc-port
                                servicegroupname: $parent.properties.name

The repeat is an object by itself, and repeat-list and repeat-item are attributes for the repeat object.

  • repeat-list is a mandatory attribute that identifies the list that the component iterates on.
  • repeat-item is optional, and is used to give a friendly name to the current item in the iteration.

If not specified, the current item can be accessed using the expression $repeat-item. The last component in the above example can also be written as follows:

          -
          name: members-svcg-comp
          type: ns::servicegroup_servicegroupmember_binding
          repeat:
            repeat-list: $parameters.svc-servers
          properties:
                 ip: $repeat-item
                 port: $parameters.svc-port
                 servicegroupname: $parent.properties.name

In addition to being able to refer to the current item white iterating over a list, it is also possible to refer to the current index of the item in the list using repeat-index. In the following example, repeat-index is used to calculate a port number based on the current index:

             name: services
             type: ns::service
             repeat:
                repeat-list: $parameters.app-services
                repeat-item: srv
             properties:
                 ip: $parameters.app-ip
                 port: $parameters.base-port + repeat-index
                 servicegroupname: $parent.properties.name

Similar to the repeat-item construct, you can assign a different variable name to refer to the current index of the iteration. The previous example is equivalent to the following example:

     -
             name: services
             type: ns::service
             repeat:
                repeat-list: $parameters.app-services
                repeat-item: srv
                repeat-index: idx
             properties:
                 ip: $parameters.app-ip
                 port: $parameters.base-port + $idx
                 servicegroupname: $parent.properties.name

Repeat construct

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