MEAD Template Parameterization

Overview

Parameterization allows for the ability to use a single MEAD to be deployed multiple times with different values for the VDU parameters provided at deploy time. In contrast, a non-parameterized MEAD has static values for the parameters that might limit the number of concurrent MEAs that can be deployed using a single MEAD. For example, deploying an instance of a non-parameterized template that has fixed IP addresses specified for network interface a second time without deleting the first instance of MEA would lead to an error.

Non-parameterized MEAD template

Find below an example of a non-parameterized MEAD where the text italicized are the VDU parameters and text in bold are the values for those VDU parameters that get applied to the VDU when this template is deployed. The next section will illustrate how the below non-parameterized template can be parameterized and re-used for deploying multiple MEAs.

Here is the sample template:

tosca_definitions_version: tosca_simple_profile_for_mec_1_0_0

description: MEA TOSCA template with input parameters

metadata:
  template_name: sample-tosca-mead

topology_template:

  node_templates:
    VDU1:
      type: tosca.nodes.mec.VDU.Apmec
      properties:
        image: cirros-0.3.5-x86_64-disk
        flavor: m1.tiny
        availability_zone: nova
        mgmt_driver: noop
        config: |
          param0: key1
          param1: key2

    CP1:
      type: tosca.nodes.mec.CP.Apmec
      properties:
        management: True
        anti_spoofing_protection: false
      requirements:
        - virtualLink:
            node: VL1
        - virtualBinding:
            node: VDU1

    CP2:
      type: tosca.nodes.mec.CP.Apmec
      properties:
        anti_spoofing_protection: false
      requirements:
        - virtualLink:
            node: VL2
        - virtualBinding:
            node: VDU1

    CP3:
      type: tosca.nodes.mec.CP.Apmec
      properties:
        anti_spoofing_protection: false
      requirements:
        - virtualLink:
            node: VL3
        - virtualBinding:
            node: VDU1

    VL1:
      type: tosca.nodes.mec.VL
      properties:
        network_name: net_mgmt
        vendor: Apmec

    VL2:
      type: tosca.nodes.mec.VL
      properties:
        network_name: net0
        vendor: Apmec

    VL3:
      type: tosca.nodes.mec.VL
      properties:
        network_name: net1
        vendor: Apmec

Parameterized MEAD template

This section will walk through parameterizing the template in above section for re-use and allow for deploying multiple MEAs with the same template. (Note: All the parameters italicized in the above template could be parameterized to accept values at deploy time). For the current illustration purpose, we will assume that an end user would want to be able to supply different values for the parameters image_name, flavor, network, management, pkt_in_network, pkt_out_network, vendor, during each deploy of the MEA.

The next step is to substitute the identified parameter values that will be provided at deploy time with { get_input: <param_name>}. For example, the instance_type: cirros-0.3.5-x86_64-disk would now be replaced as: image: {get_input: image_name}. The get_input is a reserved keyword in the template that indicates value will be supplied at deploy time for the parameter instance_type. The image_name is the variable that will hold the value for the parameter image in a parameters value file that will be supplied at MEA deploy time.

The template in above section will look like below when parameterized for image_name, flavor, network, management and remaining parameters.

Here is the sample template:

tosca_definitions_version: tosca_simple_profile_for_mec_1_0_0

description: MEA TOSCA template with input parameters

metadata:
  template_name: sample-tosca-mead

topology_template:
  inputs:
    image_name:
      type: string
      description: Image Name

    flavor:
      type: string
      description: Flavor Information

    zone:
      type: string
      description: Zone Information

    network:
      type: string
      description: management network

    management:
      type: string
      description: management network

    pkt_in_network:
      type: string
      description: In network

    pkt_out_network:
      type: string
      description: Out network

    vendor:
      type: string
      description: Vendor information

  node_templates:
    VDU1:
      type: tosca.nodes.mec.VDU.Apmec
      properties:
        image: { get_input: image_name}
        flavor: {get_input: flavor}
        availability_zone: { get_input: zone }
        mgmt_driver: noop
        config: |
          param0: key1
          param1: key2

    CP1:
      type: tosca.nodes.mec.CP.Apmec
      properties:
        management: { get_input: management }
        anti_spoofing_protection: false
      requirements:
        - virtualLink:
            node: VL1
        - virtualBinding:
            node: VDU1

    CP2:
      type: tosca.nodes.mec.CP.Apmec
      properties:
        anti_spoofing_protection: false
      requirements:
        - virtualLink:
            node: VL2
        - virtualBinding:
            node: VDU1

    CP3:
      type: tosca.nodes.mec.CP.Apmec
      properties:
        anti_spoofing_protection: false
      requirements:
        - virtualLink:
            node: VL3
        - virtualBinding:
            node: VDU1

    VL1:
      type: tosca.nodes.mec.VL
      properties:
        network_name: { get_input: network }
        vendor: {get_input: vendor}

    VL2:
      type: tosca.nodes.mec.VL
      properties:
        network_name: { get_input: pkt_in_network }
        vendor: {get_input: vendor}

    VL3:
      type: tosca.nodes.mec.VL
      properties:
        network_name: { get_input: pkt_out_network }
        vendor: {get_input: vendor}

Parameter values file at MEA deploy

The below illustrates the parameters value file to be supplied containing the values to be substituted for the above parameterized template above during MEA deploy.

image_name: cirros-0.3.5-x86_64-disk
flavor: m1.tiny
zone: nova
network: net_mgmt
management: True
pkt_in_network: net0
pkt_out_network: net1
vendor: Apmec

Note

IP address values for network interfaces should be in the below format in the parameters values file:

param_name_value:: - xxx.xxx.xxx.xxx

Key Summary

Parameterize your MEAD if you want to re-use for multiple MEA deployments.
Identify parameters that would need to be provided values at deploy time and substitute value in MEAD template with {get_input: <param_value_name>}, where 'param_value_name' is the name of the variable that holds the value in the parameters value file.
Supply a parameters value file in yaml format each time during MEA deployment with different values for the parameters.
An example of a mea-create python-apmecclient command specifying a parameterized template and parameter values file would like below:
```
apmec mea-create --mead-name <mead_name> --param-file <param_yaml_file> <mea_name>
```
Specifying a parameter values file during MEA creation is also supported in Horizon UI.
Sample MEAD parameterized templates and parameter values files can be found at https://github.com/openstack/apmec/tree/master/samples/tosca-templates/mead.

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