Interfaces

Interfaces provide a way to map logical tasks to executable operations.

Declaration

Node Types and Interfaces

node_types:
  some_type:
    ...
    interfaces:
      interface1:
        type: <interface type name>
        inputs:
          ..
        operations:
           op1:
             ...
           op2:
             ...
      interface2:
        ...

Each interface declaration under the interfaces section is a dictionary of operations.

Operation Declaration in Node Types Interfaces

node_types:
  some_type:
    interfaces:
      interface1:
        operations:
           op1:
             implementation: ...
             inputs:
               ...

Definition

Keyname	Required	Type	Description
implementation	yes	string	The script or plugin task name to execute.
inputs	no	dict	Schema of inputs that will be passed to the implementation.

Simple Mapping

node_types:

  some_type:
    interfaces:
      interface1:
        op1: plugin_name.path.to.module.task

When mapping an operation to an implementation, if there is no need to pass inputs the full mapping structure can be avoided and the implementation can be written directly.

Operation Input Schema Definition

node_types:
  some_type:
    interfaces:
      interface1:
        op1:
          implementation: ...
          inputs:
            input1:
              description: ...
              type: ...
              default: ...

Keyname	Required	Type	Description
description	no	string	Description for the input.
type	no	string	Input type. Not specifying a data type means the type can be anything (also types not listed in the valid types). Valid types: string, integer, boolean
default	no	<any>	An optional default value for the input.

Node Templates Interface Definition

Operation Inputs in Node Templates Interfaces

node_types:
  some_type:
    interfaces:
      interface1:
        op1:
          implementation: myArtifact
          inputs:
            input1:
              description: some mandatory input
            input2:
              description: some optional input with default
              default: 1000

node_templates:
  some_node:
    interfaces:
      interface1:
        op1:
          inputs:
            input1: mandatory_input_value
            input3: some_additional_input

When an operation in a node template interface is inherited from a node type or a requirement interface:

All inputs that were declared in the operation inputs schema must be provided.
Additional inputs, which were not specified in the operation inputs schema, may be passed as well.

Examples

In the following examples, we will declare an interface which will allow us to:

Configure a master deployment server using a plugin.
Deploy code on the hosts using a plugin.
Verify that the deployment succeeded using a shell script.
Start the application after the deployment ended.

For the sake of simplicity, we will not refer to requirements in these examples.

Configuring Interfaces in Node Types

Configuring the master server:

node_types:
  nodejs_app:
    derived_from: tosca.nodes.ApplicationModule
    properties:
      ...
    interfaces:
      my_deployment_interface:
        configure:
          implementation: deployer.config_in_master.configure

node_templates:
  nodejs:
    type: nodejs_app

In this example, we’ve:

Declared a deployer plugin which, by default, should execute its operations on the TOSCA manager.
Declared a node type with a my_deployment_interface interface that has a single configure operation which is mapped to the deployer.config_in_master.configure task.
Declared a nodejs node template of type nodejs_app.

node_types:
  nodejs_app:
    derived_from: tosca.nodes.ApplicationModule
    properties:
      ...
    interfaces:
      my_deployment_interface:
        configure:
          implementation: deployer.config_in_master.configure
        deploy:
          implementation: deployer.deploy_framework.deploy

node_templates:
  vm:
    type: tosca.openstack.nodes.Server
  nodejs:
    type: nodejs_app

Here we added a deploy operation to our my_deployment_interface interface.

Declaring an operation implementation within the node

You can specify a full operation definition within the node’s interface under the node template itself.

node_types:
  nodejs_app:
    derived_from: tosca.nodes.ApplicationModule
    properties:
      ...
    interfaces:
      my_deployment_interface:
        ...

node_templates:
  vm:
    type: tosca.openstack.nodes.Server
  nodejs:
    type: nodejs_app
    interfaces:
      my_deployment_interface:
        ...
        start: scripts/start_app.sh

Let’s say that we use our my_deployment_interface on more than the nodejs node. While on all other nodes, a start operation is not mapped to anything, we’d like to have a start operation for the nodejs node specifically, which will run our application after it is deployed.

Here, we’ve declared a start operation and mapped it to execute a script specifically on the nodejs node.

This comes to show that you can define your interfaces either in node_types or in node_templates depending on whether you want to reuse the declared interfaces in diffrent nodes or declare them in specific nodes.

Operation Inputs

Operations can specify inputs that will be passed to the implementation.

plugins:
  deployer:
    executor: central_deployment_agent

node_types:
  nodejs_app:
    derived_from: tosca.nodes.ApplicationModule
    properties:
      ...
    interfaces:
      my_deployment_interface:
        configure:
          ...
        deploy:
          implementation: deployer.deploy_framework.deploy
          inputs:
            source:
              description: deployment source
              type: string
              default: git
        verify:
          implementation: scripts/deployment_verifier.py

node_templates:
  vm:
    type: tosca.openstack.nodes.Server
  nodejs_app:
    type: tosca.nodes.WebServer
    interfaces:
      my_deployment_interface:
        ...
        start:
          implementation: scripts/start_app.sh
          inputs:
            app: my_web_app
            validate: true

Here, we added an input to the deploy operation under the my_deployment_interface interface in our nodejs_app node type and two inputs to the start operation in the nodejs node’s interface.