HOWTO run Flask under uwsgi on Opalstack

Here's how to spin up a basic Flask app using uwsgi on your Opalstack server:

(This example uses myuser as the shell user name and myapp as the app name.)

1. Create a new shell user via your Opalstack dashboard. You can use an existing shell user if you want.
2. Create a new uwsgi app via your Opalstack dashboard and attach it to whatever website.
3. SSH to the server as your shell user and run the following commands to install flask:

cd ~/apps/myapp
source env/bin/activate
pip install flask

4. Upload your flask project directory into ~/apps/myapp. The rest of this example assumes the project directory name is "myproject" containing an empty __init__.py file and a hello.py containing the Flask app:

# myproject/hello.py

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

5. Edit your `uwsgi.ini to change this part...

# adjust the following to point to your project
wsgi-file = /home/myuser/apps/myapp/myproject/wsgihandler.py
touch-reload =  /home/myuser/apps/myapp/myproject/wsgihandler.py

... to this:

# adjust the following to point to your project
python-path = /home/myuser/apps/myapp/myproject/
wsgi = hello:app

6. Stop the app and restart it:

~/apps/myapp/stop
sleep 2
~/apps/myapp/start

That's it, you're done :-)

The only tricky part here is figuring out the wsgi directive in your uwsgi.ini for your own project, but it will usually be projectdir:app.

If your Flask app isn't organized like the example above then feel free to post here to let me know what you've got and I'll help you wire it up.

Danos2000 No, there have been no changes on your server that would cause this.

To troubleshoot, do a full stop/start cycle of the app then immediately open your uwsgi log to see what errors are logged immediately before the most recent "no python application found" error. That should give you an indication of the module that can't be found and you can then adjust your python-path in uwsgi.ini accordingly.

If you're unsure how to proceed after viewing the log then please email our support team with the details and we'll look into it further.