Not sure if this is a bug. CSS/js in production redirect to "base url"

[fithisux]

I use swagger-ui-py==21.12.8 and locally Openapi documentation is created without problems and I can enjoy it at

http://localhost:8005/api/doc (8005 is custom).

We deploy in our preview envs, and this url works fine

https://preview-newe-2253-a9wd53-debug.preview.gfknewron.com/insight/additive-decomposition/api/doc/swagger.json

But htis one

https://preview-newe-2253-a9wd53-debug.preview.gfknewron.com/insight/additive-decomposition/api/doc/

has problems with resources

GET https://preview-newe-2253-a9wd53-debug.preview.gfknewron.com/api/doc/static/swagger-ui.css net::ERR_ABORTED 404

it should have been

https://preview-newe-2253-a9wd53-debug.preview.gfknewron.com/insight/additive-decomposition/api/doc/static/swagger-ui.css

The urls are generated from our deployment scripts.

Is there something I can do? Is this a misuse of the library on my part?

Any idea what is missing?

Python 3.10.3 on MacOS Big sur, x86-64, installed through pyenv. flask==2.1.0

[fithisux]

My init

def init():
    app = Flask(__name__)
    app.config["JSON_SORT_KEYS"] = False
    app.config.update(settings)
    app.errorhandler(Exception)(exceptions_handler)

    metrics = GunicornInternalPrometheusMetrics.for_app_factory(defaults_prefix=NO_PREFIX)
    metrics.init_app(app)

    app.before_request(log_request_start)
    app.after_request(log_request_end)

    app.add_url_rule(rule="/actuator/health", endpoint="healthcheck", view_func=healthcheck, methods=["GET"])
    app.add_url_rule(rule="/v1/additive_decomposition/summary", endpoint="/v1/additive_decomposition/summary", view_func=additive_decomposition_v1_proxy, methods=["POST"])
    logging.config.dictConfig(app.config.get("LOGGING"))

    spec = APISpec(title="Additive Decomposition API", version="0.0.1", openapi_version="3.0.2", plugins=[FlaskPlugin(), MarshmallowPlugin()])

    with app.test_request_context():
        spec.path(view=additive_decomposition_v1_proxy)
        spec.path(view=healthcheck)

    with open(DOC_DIR, "w") as f:
        json.dump(spec.to_dict(), f, indent=2)
    api_doc(app, config_path=DOC_DIR, url_prefix="/api/doc", title="API doc")

    return app

[PWZER]

@fithisux It seems that a proxy is added before calling the api_doc function, and its uri is /insight/additive-decomposition, but this proxy does not work for /api/doc/static/swagger-ui.css.

[fithisux]

Thank you @PWZER. So, this issue is outside my application. Correct?

[PWZER]

@fithisux I'm guessing you might need to use like this

api_doc(app, config_path=DOC_DIR, url_prefix="/insight/additive-decomposition/api/doc", title="API doc")

[PWZER]

@fithisux Could be the problem caused by this

spec.path(view=additive_decomposition_v1_proxy)

[dulanthaf]

@fithisux were you able to resolve this issue?

[fithisux]

I went to a different solution @dulanthaf . I used apispec. https://apispec.readthedocs.io/en/latest/

Even there I had a poblem since routes were not rewritten correctly. So I downloaded in a separate folder, called "static"

the contents of https://github.com/swagger-api/swagger-ui.

Also there I added an empty "init.py"

Now I did in my code:

spec = APISpec(title="Additive Decomposition API", version="0.0.1", openapi_version="3.0.2", plugins=[FlaskPlugin(), MarshmallowPlugin()])

    with app.test_request_context():
        spec.path(view=xxx1)
        spec.path(view=xxx2)
        spec.path(view=healthcheck)

    with open(OPENAPI_FILE, "w") as f:
        json.dump(spec.to_dict(), f, indent=2)

where (I actually dumped the json in the static folder with the rest of swagger ui js)

STATIC_DIR = os.path.dirname(static.__file__)
OPENAPI_FILE = f"{STATIC_DIR}/swagger.json"

now flask can add a route to static as

app = Flask(__name__, static_url_path="/static", static_folder=STATIC_DIR)

[dulanthaf]

I'm not sure if it's the same setup, but we use nginx for the proxy setup. So what worked for me was, add the proxy path, in your case probably url_prefix="/insight/additive-decomposition/api/doc" that includes the proxy subdirectory, and then in the nginx config, add a new location entry for the server:

location ^~ /insight/additive-decomposition/api/doc/ {
    proxy_pass http://something:port/insight/additive-decomposition/api/doc/;
}

[fithisux]

Thank you @dulanthaf this is exactly what I suspected, but our SREs did not like this solution. Thank you anyway.

[dulanthaf]

@fithisux any particular reason why the SRE's did not like the solution? I would assume it's one more entry into the existing proxy pass configuration?

[Olegt0rr]

@fithisux any particular reason why the SRE's did not like the solution? I would assume it's one more entry into the existing proxy pass configuration?

Because it's workaround, which need to be described and supported. So really good SRE should avoid this solution

[Olegt0rr]

@fithisux it happens, since template uses prefix as an absolute path

swagger-ui-py/swagger_ui/templates/doc.html

Lines 4 to 11 in 21c6270

	<head>
	<meta charset="UTF-8">
	<title> {{ title }} </title>
	<link rel="stylesheet" type="text/css" href="{{ url_prefix }}/static/swagger-ui.css" />
	<link rel="stylesheet" type="text/css" href="{{ url_prefix }}/static/index.css" />
	<link rel="icon" type="image/png" href="{{ url_prefix }}/static/favicon-32x32.png" sizes="32x32" />
	<link rel="icon" type="image/png" href="{{ url_prefix }}/static/favicon-16x16.png" sizes="16x16" />
	</head>

I.e. paths are looks like /api/doc/static/swagger-ui.css

Any external path override will cause this issue:

Making static path relative to current swagger-ui location should help to avoid this behaviour and be independent from any location overrides

  <head>
    <meta charset="UTF-8">
    <title> {{ title }} </title>
    <link rel="stylesheet" type="text/css" href="{{ relative_prefix }}/static/swagger-ui.css" />
    <link rel="stylesheet" type="text/css" href="{{ relative_prefix }}/static/index.css" />
    <link rel="icon" type="image/png" href="{{ relative_prefix }}/static/favicon-32x32.png" sizes="32x32" />
    <link rel="icon" type="image/png" href="{{ relative_prefix }}/static/favicon-16x16.png" sizes="16x16" />
  </head>

So it should be rendered like this

  <head>
    <meta charset="UTF-8">
    <title> {{ title }} </title>
    <link rel="stylesheet" type="text/css" href="doc/static/swagger-ui.css" />
    <link rel="stylesheet" type="text/css" href="doc/static/index.css" />
    <link rel="icon" type="image/png" href="doc/static/favicon-32x32.png" sizes="32x32" />
    <link rel="icon" type="image/png" href="doc/static/favicon-16x16.png" sizes="16x16" />
  </head>

[Olegt0rr]

@fithisux ,

I've made my suggestions with PR mentioned above.

But if you want workaround right now:

class ApplicationDocumentRelative(ApplicationDocument):
    @property
    def doc_html(self):
        doc_location_split = self.url_prefix.split("/")
        static_relative_location = doc_location_split.pop()
        self.set_relative_swagger_url()
        return self.env.get_template("doc.html").render(
            url_prefix=static_relative_location,
            title=self.title,
            config_url=self.swagger_json_uri_absolute,
            parameters=self.parameters,
            oauth2_config=self.oauth2_config,
        )

    def set_relative_swagger_url(self):
        split_path = self.swagger_json_uri_absolute.split("/")
        swagger_url_relative = "/".join(split_path[-2:])
        self.parameters["url"] = f'"{swagger_url_relative}"'


def api_doc(app, **kwargs):
    doc = ApplicationDocumentRelative(app, **kwargs)

    handler = doc.match_handler()

    if not handler:
        raise RuntimeError("No match application isinstance type!")

    if not callable(handler):
        raise RuntimeError("handler is callable required!")

    return handler(doc)

Result:

[fithisux]

Thank you very much. I do not work in this project anymore.