Add a Prefix to All Flask Routes

Add a prefix to all Flask routes

The answer depends on how you are serving this application.

Sub-mounted inside of another WSGI container

Assuming that you are going to run this application inside of a WSGI container (mod_wsgi, uwsgi, gunicorn, etc); you need to actually mount, at that prefix the application as a sub-part of that WSGI container (anything that speaks WSGI will do) and to set your APPLICATION_ROOT config value to your prefix:

app.config["APPLICATION_ROOT"] = "/abc/123"

@app.route("/")
def index():
    return "The URL for this page is {}".format(url_for("index"))

# Will return "The URL for this page is /abc/123/"

Setting the APPLICATION_ROOT config value simply limit Flask's session cookie to that URL prefix. Everything else will be automatically handled for you by Flask and Werkzeug's excellent WSGI handling capabilities.

An example of properly sub-mounting your app

If you are not sure what the first paragraph means, take a look at this example application with Flask mounted inside of it:

from flask import Flask, url_for
from werkzeug.serving import run_simple
from werkzeug.middleware.dispatcher import DispatcherMiddleware
 
app = Flask(__name__)
app.config['APPLICATION_ROOT'] = '/abc/123'
 
@app.route('/')
def index():
    return 'The URL for this page is {}'.format(url_for('index'))

def simple(env, resp):
    resp(b'200 OK', [(b'Content-Type', b'text/plain')])
    return [b'Hello WSGI World']

app.wsgi_app = DispatcherMiddleware(simple, {'/abc/123': app.wsgi_app})

if __name__ == '__main__':
    app.run('localhost', 5000)

Proxying requests to the app

If, on the other hand, you will be running your Flask application at the root of its WSGI container and proxying requests to it (for example, if it's being FastCGI'd to, or if nginx is proxy_pass-ing requests for a sub-endpoint to your stand-alone uwsgi / gevent server then you can either:

• Use a Blueprint, as Miguel points out in his answer.
• or use the DispatcherMiddleware from werkzeug (or the PrefixMiddleware from su27's answer) to sub-mount your application in the stand-alone WSGI server you're using. (See An example of properly sub-mounting your app above for the code to use).

How to set an api prefix in a flask application?

You have to set the SCRIPT_NAME env var with your prefix.

Please note, this is a WSGI server feature, and thus the Flask development server ignores it.

Read more at https://dlukes.github.io/flask-wsgi-url-prefix.html

How can I add a prefix to all routes with the Flask REST JSON module?

Reading the discussions on Github do the following:

# Create blueprint
api_bp = Blueprint('API', __name__, url_prefix='/api')

# Create Api instance only passing the blueprint
api = Api(blueprint=api_bp)

# register routes
api.route(PostList, 'post_list', '/posts')
api.route(PostDetail, 'post_detail', '/posts/<int:id>')

# initialize Api instance to App
api.init_app(app)

Don't forget that the view names will change. i.e view 'post_list' becomes 'API.post_list' so you have to adjust your schemes, but not your route declarations. This is also discussed in the linked Github discussion.

Add route prefix to Flask application running behing Gunicorn

If you are doing app composition, then you can use the DispatcherMiddleware trick you referenced. However, it sounds like you are trying to have a single service that is subpath mounted, but doesn't serve anything out of the "higher" paths at all.

There are several different ways to do this.

1. Replace Flask.url_map._rules with a werkzeug.routing.Submount rule factory:

   from werkzeug.routing import SubPath
   
   app = Flask(__name__)
   
   # register blueprints and extensions
   # load config, etc.
   
   app.url_map._rules = SubPath(app.config['APPLICATION_ROOT'], app.url_map._rules)
   

2. Replace Flask.url_rule_class:

   from werkzeug.routing import Rule
   
   app.url_rule_class = lambda path, **options: Rule(PREFIX + path, **options)
   

3. Replace add_url_rule, as you suggest in your question.

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