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Node Templates

node_templates represent the actual instances of node types that eventually represent the running application/service, as described in the blueprint.

node_templates are more commonly referred to as nodes. Nodes can comprise more than one instance. For example, you might define a node that contains two VMs. Each VM is a node_instance.

Declaration

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

node_templates:

  node_template_1:
    type: ...
    properties:
      ...
    capabilities:
      scalable:
        properties:
          ...
      ...
    interfaces:
      ...
    relationships:
      ...

  node_template_2:
    ...

Schema

Keyname Required Type Description
type yes string The node-type of this node template.
properties no dict The properties of the node template, matching its node type properties schema.
instances no dict Instances configuration. (Deprecated. Replaced with capabilities.scalable)
interfaces no interfaces Used for a mapping plugins to interfaces operation, or for specifying inputs for already-mapped node type operations.
relationships no relationships Used for specifying the relationships that this node template has with other node templates.
capabilities no dict Used for specifying the node template capabilities (Supported since: cloudify_dsl_1_3.) Only the scalable capability is supported.


Example

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

node_templates:
  vm:
    type: cloudify.nodes.Compute
    capabilities:
      scalable:
        properties:
          default_instances: 2
    properties:
      ip: 192.168.0.11

  nginx:
    # This node template is specified as being of the node type that was defined in the node types section
    type: nodes.Nginx
    # properties must match the nodes.Nginx type properties schema
    properties:
      port: 80
    interfaces:
      cloudify.interfaces.lifecycle:
        create:
          # inputs must match the inputs schema defined in nodes.Nginx for the create operation
          inputs:
            process:
              env:
                port: { get_property: [SELF, port] }
    relationships:
      - type: cloudify.relationships.contained_in
        target: vm

capabilities.scalable Configuration

The capabilities.scalable.properties key is used for configuring the deployment characteristics of the node template.

capabilities.scalable.properties Schema

Keyname Required Type Default Description
default_instances no integer 1 The number of node-instances this node template has.
min_instances no integer 0 The minimum number of permitted node instances. (Not enforced by scale workflow)
max_instances no integer UNBOUNDED The maximum number of permitted node instances. (Not enforced by scale workflow)

Example:

node_templates:
  vm:
    type: cloudify.openstack.nodes.Compute
    capabilities:
      scalable:
        properties:
          default_instances: 5

In the above example, the vm node has 5 instances when deployed.

Additional information about number of instances combined with relationships can be found in the relationships specification.