Running flask-migrate on heroku produces error
alembic, flask-migrate, heroku, python
Solution
I was struggling with this for some time and even posted on the Heroku python forums, but no replies so far. To solve the issue I decided not to run the migration remotely on Heroku, but to run the migration on my development machine and pass the production database address instead. So I do this:
- Sync the development db with production (when using Heroku you can easily do this with heroku pg:pull, you have to drop your local db prior to calling this method though)
- Assuming your models are already updated, run the python app.py db migrate. Important: I started getting the original error on my local too, I figured out I have to be in the exact same directory where my app.py is, otherwise I get the error.
- Review your auto-generated migration scripts
- Upgrade your local db with python app.py db upgrade
- Change the settings for your app to use the production db instead of your local development db and then run python app.py db upgrade again
After some thinking it struck me that this might have been the way this tool was designed to work. Although it still would be nice to be able to run the migrations remotely from Heroku, I'll settle for my solution as it is quicker and does the job.
Problem
I'm trying to use flask-migrate to version my database locally and then reflect the changes in production (Heroku). So far I managed to successfully version the local database and upgrade it, so now I wanted to reflect this on Heroku. To do this I pushed the latest code state to Heroku together with the newly created migrations folder and updated requirements.txt. I saw the dependencies were successfully installed: ``` Successfully installed Flask-Migrate alembic Flask-Script Mako ``` Then, I tried: ``` $ heroku run python app/hello.py db upgrade ``` Unfortunately I got this in response: ``` Running `python app/hello.py db upgrade` attached to terminal... up, run.4322 Traceback (most recent call last): File "app/hello.py", line 37, in <module> manager.run() File "/app/.heroku/python/lib/python2.7/site-packages/flask_script/__init__.py", line 405, in run result = self.handle(sys.argv[0], sys.argv[1:]) File "/app/.heroku/python/lib/python2.7/site-packages/flask_script/__init__.py", line 384, in handle return handle(app, *positional_args, **kwargs) File "/app/.heroku/python/lib/python2.7/site-packages/flask_script/commands.py", line 145, in handle return self.run(*args, **kwargs) File "/app/.heroku/python/lib/python2.7/site-packages/flask_migrate/__init__.py", line 97, in upgrade config = _get_config(directory) File "/app/.heroku/python/lib/python2.7/site-packages/flask_migrate/__init__.py", line 37, in _get_config config.set_main_option('script_location', directory) File "/app/.heroku/python/lib/python2.7/site-packages/alembic/config.py", line 142, in set_main_option self.file_config.set(self.config_ini_section, name, value) File "/app/.heroku/python/lib/python2.7/ConfigParser.py", line 753, in set ConfigParser.set(self, section, option, value) File "/app/.heroku/python/lib/python2.7/ConfigParser.py", line 396, in set raise NoSectionError(section) ConfigParser.NoSectionError: No section: 'alembic' ``` I googled to find what this might be and it looks like the config file can't be opened, however I have no idea what can be done to fix that. How come this works locally but not on Heroku?