Node Templates

node_templates represent instances of Node Types which would eventually represent a running application/service as described in the service template.

Declaration

The node_templates section in the DSL is a dictionary where each key is a node template.

node_templates:

  node_template_1:
    type: ...
    artifacts:
      ...
    properties:
      ...
    interfaces:
      ...
    requirements:
      ...

  node_template_2:
    ...

Definition

Keyname	Required	Type	Description
type	yes	string	The node_type of this node template.
artifacts	no	dict	See TOSCA Artifact definition
properties	no	dict	The properties of the node template matching its node type properties schema.
interfaces	no	interfaces	Used for mapping plugins to interfaces operation or for specifying inputs for already mapped node type operations.
requirements	no	requirements	Used for specifying the requirements this node template has.

Example

YAML

node_types:
  # The following node type is used in the node templates section
  nodes.Nginx:
    derived_from: tosca.nodes.WebServer
    properties:
      port:
        description: The default listening port for the Nginx server.
        type: integer
    interfaces:
      Standard:
        create:
          implementation: scripts/install-nginx.sh
          inputs:
            process:
              default:
                env:
                  port: 80
        start: scripts/start-nginx.sh

node_templates:
  vm:
    type: tosca.nodes.Compute
    properties:
      ip: 192.168.0.11

  nginx:
    # We specify that this node template is of the node type we defined in the node types section
    type: nodes.Nginx
    # properties should match nodes.Nginx type properties schema
    properties:
      port: 80
    interfaces:
      Standard:
        create:
          # inputs should match the inputs schema defined in nodes.Nginx for the create operation
          inputs:
            process:
              env:
                port: { get_property: [SELF, port] }
    requirements:
      - type: tosca.requirements.contained_in
        target: vm

PYTHON

import unfurl
from typing import Sequence
import tosca
from tosca import Eval, Property
import unfurl.configurators.shell


class NodesNginx(tosca.nodes.WebServer):
    port: int

    def create(self, **kw):
        return unfurl.configurators.shell.ShellConfigurator(
            command="scripts/install-nginx.sh",
            inputs={
                "process": {
                    "env": {
                        "port": Eval({"get_property": ["SELF", "port"]})
                    }
                }
            },
        )

    def start(self, **kw):
        return unfurl.configurators.shell.ShellConfigurator(
            command="scripts/start-nginx.sh",
        )


vm = tosca.nodes.Compute("vm")
vm.ip = "192.168.0.11"

nginx = NodesNginx("nginx", port=80)

nginx.host = tosca.relationships.HostedOn()
nginx.host.target = vm

__all__ = ["NodesNginx", "vm", "nginx"]