os.getenv() is not pulling a variable I previously declare

Question

I'm new to python and I cannot seem to figure out why I cannot get the os.getenv() function to work. It keeps returning None which is the default value if something is not there. Here is my code:

import os
import datetime
import plaid
from flask import Flask
from flask import render_template
from flask import request
from flask import jsonify

app = Flask(__name__)

PLAID_CLIENT_ID='entercharhere'
PLAID_ENV='sandbox'

#edit here
os.environ['PLAID_CLIENT_ID']='entercharhere'
os.environ['PLAID_ENV']='sandbox'

print(PLAID_CLIENT_ID)

# Fill in your Plaid API keys - https://dashboard.plaid.com/account/keys
PLAID_CLIENT_ID = os.getenv('PLAID_CLIENT_ID')
# Use 'sandbox' to test with Plaid's Sandbox environment (username: user_good,
# password: pass_good)
# Use `development` to test with live users and credentials and `production`
# to go live
PLAID_ENV = os.getenv('PLAID_ENV','sandbox')

print(PLAID_CLIENT_ID)

The output I am receiving is entercharhere and None

EDIT

I wound up switching my declaration of variables to send them to the environment using this:

os.environ['PLAID_CLIENT_ID']='entercharhere'
os.environ['PLAID_ENV']='sandbox'

Is this the best way to do it?

Answer 1

Works perfectly:

import os

os.environ['SOMEVAR'] =  'bla'

print(os.getenv('SOMEVAR'))

# in your shell: export SOMEVAR1="blabla"
print(os.getenv('SOMEVAR1'))

Gives:
bla
blabla