Problem

Flask app returns None when an environmental variable os.environ.get() is rendered in template mapboxgl.accessToken = {{ mapbox_access_token }}.

Workfiles

Environmental variable is saved in ~/.bashrc: export MAPBOX_ACCESS_TOKEN='XXXXXXXX'

from flask import Flask, render_template
import os

app = Flask(__name__)

@app.route('/')
def hello_world():

    access_token = os.environ.get('MAPBOX_ACCESS_TOKEN')
                                                                                                                                                                                                                 
    return render_template('index.html', mapbox_access_token=access_token)

if __name__ == '__main__':
    app.run()

The error appears to be in this line access_token = os.environ.get('MAPBOX_ACCESS_TOKEN'), as I tried replacing with access_token = XXXXXXXX which renders fine. However, obviously I want to avoid hard-coding sensitive information to the file.