Flask Environment Manager

A Flask environment manager for copying parameters from a source into the Flask app config, while also abiding by an override whitelist.

Currently, this packaged supports overriding the config from:

• os.environ via OsEnvironmentManager
• AWS SSM via SsmEnvironmentManager

Installation

Install and update using pip:

pip install -U flask-environment-manager

Getting Started

Before using the Environment Manager, you must ensure the following is set up in your Flask app config:

• ENV_OVERRIDE_WHITELIST

Example

{
    "ENV_OVERRIDE_WHITELIST": [
        "ENV_VAR_1",
        "ENV_VAR_2",
        "ENV_VAR_3",
        "ENV_VAR_4"
    ],
}

The keys stored in the whitelist will be the only keys updated in the config.

Managers

SSM Environment Manager

This manager can be imported with from flask_environment_manager import SsmEnvironmentManager

This manager requires the following to be definied in the Flask app config, in addition the the whitelist:

• AWS_SSM_ACCESS_KEY
• AWS_SSM_ACCESS_SECRET
• AWS_SSM_REGION

This manager will connect to AWS SSM and get parameters from a given path.

The following snippet will load all parameters nested under the /directory path (recursively).

from flask_environment_manager import SsmEnvironmentManager
manager = SsmEnvironmentManager(app, "/directory")
manager.load_into_config()

It is important to note that parameters are stored as their final name in the path. For example, the parameter stored at /directory/params/param will be stored as param.

Local Development

The SSM Manager also provides a way to work with a local config file, instead of SSM. This is useful when working locally or in a way where you don't have access to SSM.

You can access this by passing config_pyfile into the constructor. This will make use of config.from_pyfile when reading the file name passed in.

Example:

from flask_environment_manager import SsmEnvironmentManager
manager = SsmEnvironmentManager(app, "/directory", config_pyfile='local_config.py')
manager.load_into_config()

Where local_config.py looks something like:

KEY1=1
KEY2="2"
KEY3=True

OS Environment Manager

This manager can be imported with from flask_environment_manager import OsEnvironmentManager

This manager will use the os.environ keys and values to update the app.config

from flask_environment_manager import OsEnvironmentManager
manager = OsEnvironmentManager(app)
manager.load_into_config()

Developing

The build pipeline requires your tests to pass and code to be formatted

Make sure you have Python 3.x installed on your machine (use pyenv).

Install the dependencies with pipenv (making sure to include dev and pre-release packages):

pipenv install --dev --pre

Configure your environment:

pipenv shell && export PYTHONPATH="$PWD"

Run the tests:

pytest

Or with logging:

pytest -s

Or tests with coverage:

pytest --cov=./

Format the code with Black:

black $PWD

Releases

Cleanup the (.gitignored) dist folder (if you have one):

rm -rf dist

Notch up the version number in setup.py and build:

python3 setup.py sdist bdist_wheel

Push to PyPi (using the ScholarPack credentials when prompted)

python3 -m twine upload --repository-url https://upload.pypi.org/legacy/ dist/*

Links

• Releases: https://pypi.org/project/flask-environment-manager/
• Code: https://github.com/ScholarPack/flask-environment-manager