Overview

Nussknacker can use services documented with OpenAPI specification. We use Swagger to parse OpenAPI, versions 2.x and 3.x are supported (version 2.x should be considered as deprecated).

Nussknacker applies following rules when mapping OpenAPI services to enrichers:

• Each operation is mapped to one enricher
• If operationId is configured it's used as enricher name, otherwise we create it as concatenation of HTTP method, path and parameters (to provide some level of uniqueness)
• Parameters (path, query of header) are used to define enricher parameters
• If specification declares body parameter as object, we expand to parameter list
• We expect operation to define 200/201 response, returned object is the one that is the result of enricher
• We map 404 HTTP code to null value of enricher
• We use externalDocs.url to extract documentation link

Table below describes data types that OpenAPI integration handles:

OpenAPI Type	OpenAPI Format	Type in Nussknacker
boolean		Boolean
string		String
string	date-time	LocalDateTime
integer		Long
number		BigDecimal
number	double	Double
number	float	Double
array		array
map/object		record

OpenAPI integration can handle schema references. For objects and maps we use properties to define structure. For arrays we use items to define type of elements.

Configuration

Sample configuration:

components {
  service1: {
      type: openAPI  
      url = "http://myservice.com/swagger"
      rootUrl = "http://myservice.com/endpoint"
      security {
          apikey {
              type = "apiKey"
              apiKeyValue = "34534asfdasf"
          }
      }
      namePattern: "customer.*"
      allowedMethods: ["GET", "POST"]
  }
}

Parameter	Required	Default	Description
url	true		URL with OpenAPI resource
rootUrl	false		Base URL of service, can be used to override value from OpenAPI in NAT settings
allowedMethods	false	["GET"]	Usually only GET services should be used as enrichers are meant to be idempotent and not change data
namePattern	false	.*	Regexp for filtering operations by operationId (i.e. enricher name)
security	false		Configuration for authentication. Currently only apiKey is supported