System packages

Cortex looks for a file named dependencies.sh in the top level Cortex project directory (i.e. the directory which contains cortex.yaml). For example:

./my-classifier/
├── cortex.yaml
├── predictor.py
├── ...
└── dependencies.sh

dependencies.sh is executed with bash shell during the initialization of each replica (before installing Python packages in requirements.txt or conda-packages.txt). Typical use cases include installing required system packages to be used in your Predictor, building Python packages from source, etc.

Here is an example dependencies.sh, which installs the tree utility:

apt-get update && apt-get install -y tree

The tree utility can now be called inside your predictor.py:

# predictor.py
import subprocess

class PythonPredictor:
    def __init__(self, config):
        subprocess.run(["tree"])
    ...