Connexion

Connexion is a framework on top of Flask to automagically handle your REST API requests based on Swagger 2.0 Specification files in YAML.

How to use

Put your API YAML inside a folder in the root path of your application (e.g swagger/) and then do

import connexion

app = connexion.App(__name__, specification_dir='swagger/')
app.add_api('my_api.yaml')
app.run(port=8080)

See the Connexion Pet Store Example Application for details.

Parameterization

Connexion uses Jinja2 to allow the parameterization of specifications.

The specification arguments can be defined globally for the application or for each specific API:

app = connexion.App(__name__, specification_dir='swagger/', arguments={'global': 'global_value'})
app.add_api('my_api.yaml', arguments={'api_local': 'local_value'})
app.run(port=8080)

If a value is provided both globally and on the API then the API value will take precedence.

Endpoint Routing

Connexion uses the operationId from each Operation Object to identify which function should handle each URL.

For example:

paths:
  /hello_world:
    post:
      operationId: myapp.api.hello_world

If you provided this path in your specification POST requests to http://MYHOST/hello_world would be handled by the function hello_world in myapp.api. Optionally you can include x-router-controller in your operation definition, making operationId relative:

paths:
  /hello_world:
    post:
      x-router-controller: myapp.api
      operationId: hello_world

To customize this behavior, connexion can use alternative Resolvers, for example RestyResolver. The RestyResolver will compose an operationId based on the path and HTTP method of the endpoints in your specification:

from connexion.resolver import RestyResolver

app = connexion.App(__name__)
app.add_api('swagger.yaml', resolver=RestyResolver('api'))

paths:
  /:
    get:
       # Implied operationId: api.get
  /foo:
    get:
       # Implied operationId: api.foo.search
    post:
       # Implied operationId: api.foo.post

  '/foo/{id}':
    get:
       # Implied operationId: api.foo.get
    put:
       # Implied operationId: api.foo.post
    copy:
       # Implied operationId: api.foo.copy
    delete:
       # Implied operationId: api.foo.delete

RestyResolver will give precedence to any operationId encountered in the specification. It will also respect x-router-controller. You may import and extend connexion.resolver.Resolver to implement your own operationId (and function) resolution algorithm.

Additionally you can also define a basePath on the top level of the API specification, which is useful for versioned APIs. If you wanted to serve the previous endpoint from http://MYHOST/1.0/hello_world you could do:

basePath: /1.0

paths:
  /hello_world:
    post:
      operationId: myapp.api.hello_world

Other alternative if you don't want to include the base path in your specification is provide the base path when adding the API to your application:

app.add_api('my_api.yaml', base_path='/1.0')

Response Serialization

If the specification defines that a endpoint returns json connexion will automatically serialize the return value for you and set the right content type in the HTTP header.

Authentication and Authorization

If the specification includes a Oauth2 Security Definition compatible with the Zalando Greendale Team's infrastructure connexion will automatically handle token validation and authorization for operations that have Security Requirements. One main difference between the usual Oauth flow and the one connexion uses is that the API Security Definition must include a 'x-tokenInfoUrl' with the URL to use to validate and get the token information. Connexion expects to receive the Oauth token in the Authorization header field in the format described in RFC 6750 section 2.1.

Swagger JSON

Connexion makes the Swagger specification in JSON format available from swagger.json in the base path of the API.

Swagger UI

The Swagger UI for an API is available, by default, in {base_path}/ui/ where base_path is the base path of the API.

You can disable the swagger ui either at application level:

app = connexion.App(__name__, port = 8080, specification_dir='swagger/', swagger_ui=False)
app.add_api('my_api.yaml')

You can also disable it at API level:

app = connexion.App(__name__, port = 8080, specification_dir='swagger/')
app.add_api('my_api.yaml', swagger_ui=False)

Server Backend

By default connexion uses the default flask server but you can also use Tornado as the http server, to do so set server to tornado:

import connexion

app = connexion.App(__name__, port = 8080, specification_dir='swagger/', server='tornado')

You can use the Flask WSGI app with any WSGI container, e.g. using Flask with uWSGI:

app = connexion.App(specification_dir='swagger/')
application = app.app # expose global WSGI application object

$ sudo pip3 install uwsgi
$ uwsgi --http :8080 -w app -p 16  # use 16 worker processes

You can run uwsgi with a large number of worker processes to get high concurrency.

See the uWSGI documentation for more information.

Releasing Connexion

Build and upload new version to PyPI:

$ ./release.sh <NEW-VERSION>

License

Copyright 2015 Zalando SE

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.