Falcon application can not render Openapi(swagger) specification

Question

Hello everyone we are running a Falcon application that uses the falcon-apispec library to generate OpenAPI specifications.

Here is our code that initializes the definition:

import falcon

from apispec import APISpec
from falcon_apispec import FalconPlugin
from kubernetes import config
from api.admission_response import AdmissionResponse
from api.health import Health
from api.k8s_config_validator import K8sConfigValidator
from api.middleware.json import RequireJSON, JSONTranslator
from api.apidocs import ApiDocs

def create_app(config_validator):
    api = falcon.API(middleware=[
        RequireJSON(),
        JSONTranslator(),
    ])
    resources ={
        '/': AdmissionResponse(config_validator),
        '/api-docs': ApiDocs(),
        '/health': Health()
    }

    for r in resources:
        api.add_route(r, resources[r])

    setup_swagger_documentation(api, resources)

    # initialize k8s client
    config.load_incluster_config()

    return api


def get_app():
    return create_app(K8sConfigValidator())

def setup_swagger_documentation(api, resources):
    spec = APISpec(
        title='Admission Controller API',
        version='latest',
        openapi_version='2.0',
        plugins=[
            FalconPlugin(api)
        ],
        info=dict(description="Admission Controller API"),
    )

    for r in resources:
        spec.path(resource=resources[r])

    with open('./api/config/openapi/openapi_spec.yaml', 'w') as f:
        f.write(spec.to_yaml())

Here is our openapi-spec defintion defined:

openapi: 3.0.0
info:
  description: Admission Controller API
  title: Admission Controller API
  version: latest
paths:
  /:
    post:
      tags:
      - "API"
      parameters:
        - in: "query"
          name: "body"
          description: "List of user object"
          required: true
          schema:
            type: string
      responses:
        "200":
          description: "Success"
  /api-docs:
    get:
      tags:
      - "API Doc Endpoints"
      responses:
        "200":
          description: "Success"
  /health:
    get:
      tags:
      - "Health Endpoints"
      responses:
        "200":
          description: "Success"

And here is one of the classes that defines what should be done on a post:

class AdmissionResponse(object):

    def __init__(self, k8s_config_validator):
        self.k8s_config_validator = k8s_config_validator

    @falcon.before(validate_schema)
    def on_post(self, req, resp):
        """
        ---
        tags: ['API']
        parameters:
          - in: "query"
            name: "body"
            description: "List of user object"
            required: true
            type: string
        responses:
          "200":
            description: "Success"
        """
        admission_review = AdmissionReview(req.context['doc'])

        errors = self.k8s_config_validator.validate(admission_review)
        if errors:
            resp.context['result'] = ResponseBuilder(admission_review).not_allowed(errors)
            api.logger.info("Validations for %s of kind %s in %s failed with %s", admission_review.name(), admission_review.kind(), admission_review.namespace(), errors)
        else:
            resp.context['result'] = ResponseBuilder(admission_review).allowed()
            api.logger.info("Validations for %s of kind %s in %s passed", admission_review.name(), admission_review.kind(), admission_review.namespace())

Whenever we try to hit our hosted swagger-ui we run into this error:

Unable to render this definition The provided definition does not specify a valid version field. Please indicate a valid Swagger or OpenAPI version field. Supported version fields are swagger: "2.0" and those that match openapi: 3.0.n (for example, openapi: 3.0.0).

Does anyone know how we could resolve this? When we paste in our openapi specification to the swagger editor located here: https://editor.swagger.io/ it works just fine. Any help would be awesome!

Starnuto di topo Starnuto di topo · Accepted Answer · 2020-09-01T06:58:31

When calling APISpec, not all strings are supported. Try something like "0.0.1" (you supplied 'latest'). Also, using falcon_swagger_ui, an error may be reported if the openapi_version format is not correct (in such case, examples of valid formats are provided).

This works for me:

 spec = APISpec(
        title="My APP",
        version="0.0.1",
        openapi_version='3.0.0',
        plugins=[FalconPlugin(api)]
    )

Falcon application can not render Openapi(swagger) specification

1 Answers