How to generate OpenAPI docs (Swagger UI) page using static .yaml file with Flask?

I'm working on RESTful API flask server and I need to make endpoint to render my API using static file (.yaml). I've tried flask_swagger_ui, but I couldn't get how to specify path to local file. I'm quite new to develop RESTful API and flask servers, so I'd be happy to get some advices how to do what I want the right way.

Solution

Assuming you have a spec file called openapi.yaml. If you want to host the API docs by yourself, you can follow the following steps:

Create a file called app.py, then create two view to serve the spec file and the Swagger UI page:

from flask import Flask, render_template, send_from_directory

app = Flask(__name__)


@app.route('/docs')
def swagger_ui():
    return render_template('swagger_ui.html')


@app.route('/spec')
def get_spec():
    return send_from_directory(app.root_path, 'openapi.yaml')

Create a template called swagger_ui.html in the templates folder with the following content:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Swagger UI</title>
    <link rel="stylesheet" type="text/css" href="https://unpkg.com/swagger-ui-dist@3//swagger-ui.css" >
    <style>
      html
      {
        box-sizing: border-box;
        overflow: -moz-scrollbars-vertical;
        overflow-y: scroll;
      }

      *,
      *:before,
      *:after
      {
        box-sizing: inherit;
      }

      body
      {
        margin:0;
        background: #fafafa;
      }
    </style>
  </head>

  <body>
    <div id="swagger-ui"></div>

    <script src="https://unpkg.com/swagger-ui-dist@3/swagger-ui-bundle.js"></script>
    <script src="https://unpkg.com/swagger-ui-dist@3/swagger-ui-standalone-preset.js"></script>
    <script>
      window.onload = function() {
      const ui = SwaggerUIBundle({
        url: "{{ url_for('get_spec') }}",
        dom_id: '#swagger-ui',
        deepLinking: true,
        presets: [
          SwaggerUIBundle.presets.apis,
          SwaggerUIStandalonePreset
        ],
        plugins: [
          SwaggerUIBundle.plugins.DownloadUrl
        ],
        layout: "BaseLayout"
      })
    }
    </script>
  </body>
</html>

The final file structure will be like this:

- app.py
- templates
    - swagger_ui.html
- openapi.yaml

Now run the app with:

$ flask run

Then go to http://localhost:5000/docs.