Use Fabric to manage envdir compatible configuration data

config.py

"""
Remote environment variable configuration using envdir

This should be set up using a `fabfile/` module rather than
an individual `fabfile.py` file.

$ fab <env> config -- list environment variables (incl. values)

$ fab <env> config.set:DEBUG=False -- set a single variable
$ fab <env> config.set:DEBUG=False,SECRET=jdkjkjk -- set multiple variables

$ fab <env> config.remove:DEBUG -- remove a single variable
$ fab <env> config.remove:DEBUG,SECRET -- remove multiple variables

Requires that `env.config_dir` is set prior to running.

:author: Ben Lopatin
:license: BSD
"""
from fabric.api import task, run
from fabric.context_managers import cd, hide
from fabric.state import env


@task(default=True)
def list():
    """Lists the environment variables for the app user"""
    with hide('running', 'stdout'):
        with cd(env.config_dir):
            environment = {
                var: run("cat {}".format(var))
                for var in run("ls").split()
            }

    longest_key = max([len(i) for i in environment.keys()]) + 1
    padding = 30 if longest_key < 30 else longest_key
    print_str = "{{:<{}}} {{}}".format(padding)
    # Why not use an OrderedDict?? Because an OrderedDict only orders based on
    # the input, and the input even from `ls` was oddly not sorted
    # alphabetically.
    for var in sorted(environment.keys()):
        print print_str.format(var, environment[var])


@task
def set(**kwargs):
    """Add one or more shell variables to the app environment"""
    with hide('running', 'stdout'):
        with cd(env.config_dir):
            for var, value in kwargs.items():
                run("echo '{0}' > {1}".format(value, var))


@task
def remove(*args):
    """Remove configuration variables from the app environment"""
    with hide('running', 'stdout'):
        with cd(env.config_dir):
            envvars = [var for var in run("ls").split()]
            for env_key in args:
                if env_key not in envvars:
                    print("No such variable {0}".format(env_key))
                    continue
                run("rm {0}".format(env_key))

Application restart is a second distinct step. Would ideally be added via a decorator, optionally naming services to be restarted.

@task
@restart_services('gunicorn', 'celery')
def set(**kwargs):
    """Add one or more shell variables to the app environment"""
    with hide('running', 'stdout'):
        with cd(env.config_dir):
            for var, value in kwargs.items():
                run("echo '{0}' > {1}".format(value, var))
    return True  # Use a boolean to flag restarting or not