XOS TOSCA User Manual

The xos-tosca container is responsible to autogenerate the TOSCA interface starting from the xproto definition.

What is TOSCA?

Topology and Orchestration Specification for Cloud Applications (TOSCA), is an OASIS standard language to describe a topology of cloud based web services, their components, relationships, and the processes that manage them. The TOSCA standard includes specifications to describe processes that create or modify web services.

You can read more about it on the OASIS website.

In XOS we are extending the TOSCA specification to support our custom models and let you manage them with a simple and well known YAML interface.

Overview

When the xos-tosca container starts, it will connect to xos-core via the gRPC APIs to fetch all the xproto definition of the onboarded models, this include both core and service models. Then using the xos-genx toolchain it will generate TOSCA specification for them.

For example, the xproto definition of a compute node in XOS:

message Node::node_policy (XOSBase) {
     required string name = 1 [max_length = 200, content_type = "stripped", blank = False, help_text = "Name of the Node", null = False, db_index = False];
     required manytoone site_deployment->SiteDeployment:nodes = 2 [db_index = True, null = False, blank = False];
}

Will be transformed in a TOSCA spec:

tosca_definitions_version: tosca_simple_yaml_1_0

node_types:

    tosca.nodes.Node:
        derived_from: tosca.nodes.Root
        description: "An XOS Node"
        capabilities:
            node:
                type: tosca.capabilities.xos.Node
        properties:
            must-exist:
                type: boolean
                default: false
                description: Allow to reference existing models in TOSCA recipes
            name:
                type: string
                required: false
                description: "Name of the Node"
            

    tosca.relationships.BelongsToOne:
        derived_from: tosca.relationships.Root
        valid_target_types: [ tosca.capabilities.xos.SiteDeployment ]
    

    tosca.capabilities.xos.Node:
        derived_from: tosca.capabilities.Root
        description: Node

And a node can be added to XOS using this recipe:

tosca_definitions_version: tosca_simple_yaml_1_0

description: Load a compute node in XOS

imports:
   - custom_types/node.yaml

topology_template:
  node_templates:

    # A compute node
    GratefulVest:
      type: tosca.nodes.Node
      properties:
        name: Grateful Vest