Interfaces & validation

Both workflow and functions have inputs and outputs. The validation of these inputs and outputs can be defined in an attribute interface. Validation is used during development and during runtime.

During creation of a workflow

The interface is used to validate during creation of a workflow if all fields are correct. If input and output values of steps are compatible and if there are loops.

Runtime validation

Additionally the interface checks for the presence of values in required input values of a step during execution of a deployment. If the required input values are not found, the execution will fail before executing this step.

How to write an interface

Interfaces are defined in the key interface. This key in turn contains two keys inputs and outputs which each define the interface in the json schema standard. Take for example the interface of the function here

#...
interface:
  inputs:
    properties:
      url:
        type: string
        description: The url to fetch
      method:
        type: string
        description: The http method
      headers:
        type: object
        description: The http headers
      body:
        type: object
        description: The http body
    required: [url]
  outputs:
    properties:
      response:
        type: object
        properties:
          data:
            type: object
            description: The http response body
          status:
            type: number
            description: The http status code
          statusText:
            type: string
            description: The http status text
          headers:
            type: object
            description: The http response headers
      error:
        type: object
        properties:
          message:
            type: string
            description: The error message
          code:
            type: string
            description: The error code
          config:
            type: object
            description: The http request config
          request:
            type: object
            description: The http request
          response:
            type: object
            description: The http response
          isAxiosError:
            type: boolean
            description: Whether the error is an axios error
    required: [response]

Allowed types

Types can be of the typical primitives:

• boolean
• string
• float
• int

and the complex types:

• array
  • needs another key items
• object
  • needs another key properties

and a few special types that configure how the value is used in the input / output

• file
  • expects a string which represents a filepath
  • if a filepath is passed to this property as an output it will try to upload the file at that path and download if passed as an input. See
• env
  • expects a string
  • will be passed as environment variable
• cmdValue
  • expects a string
  • needs to be an array of strings that is passed as cmd parameters
• cmdKeyValue
  • the key of the dependency and the value are passed in the pattern --key=value

cmdValue expects an array

env, and cmdKeyValue are always strings, If any other type is passed, it will be automatically stringified.