Dynamic Subdomain Handling in a Web App (Flask)

Question

I'm going to be using flask to create a web application, and part of the application will involve a subdomain (for example, user1.appname.org).

I'm not sure how to go about creating these subdomains dynamically in the flask configuration, or how to deploy them to a production server.

What is the best way of doing this?

Sean Vieira · Accepted Answer · 2019-04-12T02:59:30.993

67

All Flask's routing constructs support the subdomain keyword argument (this includes support for route variables).

@app.route("/", subdomain="static")
def static_index():
    """Flask supports static subdomains
    This is available at static.your-domain.tld"""
    return "static.your-domain.tld"

@app.route("/dynamic", subdomain="<username>")
def username_index(username):
    """Dynamic subdomains are also supported
    Try going to user1.your-domain.tld/dynamic"""
    return username + ".your-domain.tld"

edited Apr 12 '19 at 02:59

answered Jun 14 '12 at 05:22

Sean Vieira

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Will this work running on the Flask testing localhost server? – Bruce Collie Jun 30 '12 at 12:03
3

I'm also wondering if there's a way to test this locally. I've tried adding serveral entries to my hosts file., this doesn't seem to work. – Robert Massa Jul 01 '12 at 11:20
1

@sean How woud you do something similar for custom domains. A user signs up with subdomain.example.com and then adds a custom domain such as www.mygreatsite.com ? How would I handle access to this custom domain in a Flask route? – Raj May 07 '13 at 02:29
1

@Raj - that would depend on how you are setting up those custom domains. (Better to ask a separate question with more details about your setup.) – Sean Vieira May 07 '13 at 11:46
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You should also be able to test this locally with a free service like xip.io by 37Signals – John Wheeler Jul 26 '13 at 00:57
Downvoter, care to explain so I can improve the answer? – Sean Vieira Dec 16 '15 at 02:12
@SeanVieira, do you have a boiler-plate for this setup somewhere. i need one. – s_mj Apr 11 '19 at 04:59
How does this work with class based views? – Mojimi Nov 06 '19 at 20:29

score 53 · Answer 2 · edited Oct 03 '18 at 09:50

53

To complement Sean Viera's post, you also need to set the SERVER_NAME config variable.

Documentation: http://flask.pocoo.org/docs/config/#SERVER_NAME

The name and port number of the server. Required for subdomain support (e.g.: 'myapp.dev:5000') Note that localhost does not support subdomains so setting this to “localhost” does not help. Setting a SERVER_NAME also by default enables URL generation without a request context but with an application context.

To test locally you need to add entries to your hosts file, like this:

127.0.0.1       cvshark.local
127.0.0.1       robert.cvshark.local
127.0.0.1       www.cvshark.local

edited Oct 03 '18 at 09:50

Georgy K

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answered Jul 01 '12 at 11:50

Robert Massa

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I don't understand the example they give: 'myapp.dev:5000'. Is myapp the subdomain and dev the hostname? – compie Oct 31 '15 at 06:28
@compie Yes, that's correct. – Robert Massa Nov 18 '15 at 08:19
2

This is the better answer; it goes beyond the documentation and solves the trickier stuff. – jds May 25 '16 at 23:47
2

but can you add DYNAMIC entries to the host file? – Michael Ilie Feb 10 '18 at 14:24
@MichaelIlie Yes you can, look at the last route in Sean Vieira answer. – Yassine Faris Jun 04 '18 at 13:30

Dynamic Subdomain Handling in a Web App (Flask)

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