Heroku deployment - requirements.txt rejection (failed to compile python app)

Question

Sorry if i am asking wrong questions / not providing enough info, but its a first post for me... i am getting the rejected push to heroku as shown here, i think that its an issue with the requirements.text file, but as a noob to the dev world i am a bit stuck on working out which requirement is failing? It a tutorial project so not sure why its failing as should be simple? Any help appreciated!! Thanks in advance. Currently in a venv with 3.7.4 python version. Is it as simple as reverting down to 3.7.3 python?

─ git push heroku master         
Enumerating objects: 171, done.
Counting objects: 100% (171/171), done.
Delta compression using up to 4 threads
Compressing objects: 100% (160/160), done.
Writing objects: 100% (171/171), 34.72 KiB | 1015.00 KiB/s, done.
Total 171 (delta 77), reused 4 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> Python app detected
remote:  !     Python has released a security update! Please consider upgrading to python-3.7.3
remote:        Learn More: https://devcenter.heroku.com/articles/python-runtimes
remote: -----> Installing python-3.7.4
remote: -----> Installing pip
remote: -----> Installing SQLite3
remote: -----> Installing requirements with pip
remote:  !     Push rejected, failed to compile Python app.
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !       Push rejected to nameless-shelf-49036.
remote: 
To https://git.heroku.com/nameless-shelf-49036.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/nameless-shelf-49036.git'

requirements.txt

atomicwrites==1.3.0
attrs==19.1.0
Click==7.0
coverage==4.5.4
decorator==4.4.0
Flask==1.1.1
-e [email protected]:JRRS1982/flask-tutorial.git@dbe1045a03679a1703b1f884d61ff1310dc2269e#egg=flaskr
importlib-metadata==0.19
itsdangerous==1.1.0
Jinja2==2.10.1
MarkupSafe==1.1.1
more-itertools==7.2.0
packaging==19.1
pluggy==0.12.0
public==2019.4.13
py==1.8.0
pyparsing==2.4.2
pytest==5.1.2
self==2019.4.13
six==1.12.0
virtualenv==16.7.4
waitress==1.3.1
wcwidth==0.1.7
Werkzeug==0.15.5
zipp==0.6.0

setup.cfg

[tool:pytest]
testpaths = tests

[coverage:run]
branch = True
source = flaskr

setup.py

from setuptools import find_packages, setup

setup(
  name='flaskr',
  version='1.0.0',
  packages=find_packages(),
  include_package_data=True,
  zip_safe=False,
  install_requires=[
    'flask',
  ],
)

Answer 1

For me, this was fixed by downgrading the patch release.

$ cat runtime.txt
3.7.3

At the time I wrote this, Heroku doesn't list support for 3.7.4.

https://devcenter.heroku.com/articles/python-support

Answer 2

Appreciate it - after at least a few hours I think i discovered that the problem is that the database is SQLite3, which isn't supported by Heroku...

Really dumb as this was a tutorial for flask, a python framework and the recommended deployment is Heroku... which doesn't support the DB!

Would have been a lot less headache if they had let us/me know during the tutorial, or suggested we use a PostGres if we wanted to deploy (complete the tutorial) or something else. Would have like to have deployed, but not confident in swapping the DB out so will leave it local with some screenshots in the readme as works otherwise. Thank you :)