Defining Django App Dependencies

Overview

There are two files that control app dependencies: setup.py and requirements.txt.

setup.py is a list of "abstract" dependencies without a specification as to their source.

requirements.txt is more specific about source and version number.

Packaging dependencies

In the project's root directory:

$ pip freeze > requirements.txt

Creating this file in Windows, even after changing the line endings to Unix-style line endings, caused an error when running pip install on the the production Linux server (in codec.py).

pip freeze will list everything installed via pip in an environment. Some of these thing will not be requirements of the web app, and should be removed from requirements.txt.

psycopg2 will throw an error if PostgreSQL is not installed on the system first.

Lines can be commented out in requirements.txt with the pound (#) character.

Deploying local packages

Upload the package distribution with scp (works on Mac terminal and Windows Powershell)

$ scp -i ~/.ssh/app_aws.pem /path/to/package/dist/package-0.1.zip eb_user@ec2-x.x.x.x.us-west-2.compute.amazonaws.com:package-0.1.zip

Replacing

• ~/.ssh/app_aws.pem with path to .pem file containing key for the AWS app user.
• /path/to/package/dist/package-0.1.zip with the path of the actual python package.
• ec2-x.x.x.x.us-west-2.compute.amazonaws.com with actual Public DNS of the app, from AWS Management Console > Services > EC2 > Intances > Instances > instance-name > Public DNS
• :package-0.1.zip with the name given to the file on the server (required)

Then from the Django project directory:

$ pip install ../package-0.1.zip

Installing dependences

$ pip install -r requirements.txt

Notes

See also

• install_requires vs Requirements files - Python Packaging User Guide