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pythonflaskheroku

Catching a subdomain in Flask but with custom domain name hosted on Heroku

Basically, I am trying to catch subdomains for my website (such as www.example.com or help.example.com). I followed the instructions of solutions such as this and this. For some reason, it identifies as:

This site can’t be reached. Check if there is a typo in www.example.com.

In general, this is what most answers said:

  1. Use the subdomain="<subdomain>" argument in the decorator declaration in Flask.
  2. Declare the server name i.e. app.config['SERVER_NAME'] = "example.com:33507" N.B. -> I wrote 33507 as the port Heroku uses.

But even after performing all of these steps, it still didn't work.

Solution

  • The following Flask example code will respond to a subdomain called "api" and serve up the decorated api_index route. Note for this to work I didn't specify the port for the server name config.

    from flask import Flask, jsonify

app = Flask(__name__, subdomain_matching=True)
app.config['SERVER_NAME'] = "example.com"


@app.route("/")
def index():
    return "Welcome"


@app.route("/", subdomain="api")
def api_index():
    return jsonify({"message": "Welcome"})

    In Heroku, you will need to add a custom domain for each subdomain you require. It is possible to use a wildcard but you will have to provide your own certificate.

    I've just tried this successfully on Heroku with the following Procfile

    web: gunicorn app:app --log-file=-

    And the following dependencies using Pipenv

    [[source]]
url = "https://pypi.org/simple"
verify_ssl = true
name = "pypi"

[packages]
flask = "*"
gunicorn = "*"

[dev-packages]

[requires]
python_version = "3.11"

    If this doesn't help, you can edit your message to include your code?