How do I run a Python script that is part of an application I uploaded in an AWS SSH session?

Question

I'm trying to run a Python script I've uploaded as part of my AWS Elastic Beanstalk application from my development machine, but can't figure out how to. I believe I've located the script correctly, but when I attempt to run it under SSH, I get an import error.

For example, I have a Flask-Migrate migration script as part of my application (pretty much the same as the example in the documentation), but after successfully SSHing to my EB instance with

> eb ssh

and locating the script with

$ sudo find / -name migrate.py

when I run in the directory (/opt/python/current) where I located it with

$ python migrate.py db upgrade

at the SSH prompt I get

Traceback (most recent call last):
  File "db_migrate.py", line 15, in <module>
    from flask.ext.script import Manager
ImportError: No module named flask.ext.script

even though my requirements.txt (present along with the rest of my files in the same directory) has flask-script==2.0.5.

On Heroku I can accomplish all of this in two steps with

> heroku run bash
$ python migrate.py db upgrade

Is there equivalent functionality on AWS? How do I run a Python script that is part of an application I uploaded in an AWS SSH session? Perhaps I'm missing a step to set up the environment in which the code runs?

Answer 1

To migrate your database the best is to use container_commands, they are commands that will run every time you deploy your application. There is a good example in the EBS documentation (Step 6) :

container_commands:
  01_syncdb:    
    command: "django-admin.py syncdb --noinput"
    leader_only: true

The reason why you're getting an ImportError is because EBS installs your packages in a virtualenv. Before running arbitrary scripts in your application in SSH, first change to the directory containing your (latest) code with

cd /opt/python/current

and then activate the virtualenv

source /opt/python/run/venv/bin/activate

and set the environment variables (that your script probably expects)

source /opt/python/current/env