A helping hand to manage your settings among different environments

Intro

Managing application configuration that runs on multiple environments can be tough. So, envelop comes to help you pretend you have only one settings file that magically works whenever you deploy.

Here at Yipit, we use Chef to coordinate the deploy process and to maintain the configuration, using attributes or data bags.

After that, we use envdir to run our applications with variables set in Chef. Then, we use envelop to read those variables and feed the application configuration system.

Production

The system environment is the first place envelop will try to find things. So, when the application runs inside of an environment with the right variables set, it will just work.

So, if you know you have environment variables DATABASE_URI and ALLOWED_IPS like this:

$ export DATABASE_URI=mysql://root@localhost:3306/mydb
$ export ALLOWED_IPS=10.0.0.1,10.0.0.2

The application settings glue code will look like this:

>>> from envelop import Environment
>>> env = Environment()
>>> dburi = env.get_uri('DATABASE_URI')
>>> dburi.host
u'localhost'
>>> dburi.port
3306
>>> env.get_list('ALLOWED_IPS')
['10.0.0.1', '10.0.0.2']

Local

If you just want to load things from a file locally, the Environment.from_file() constructor will help you out.

>>> from envelop import Environment
>>> env = Environment.from_file('/etc/app.cfg')
>>> env.get_bool('BOOL_FLAG')
True
>>> env.get_float('FLOAT_VAL')
3.14

The file app.cfg will look like this:

BOOL_FLAG: True

FLOAT_VAL: 3.14

From a folder

You can also load variables from a folder, where each file will be an environment variable and the file's content will be the value. Just like envdir.

Now, say that you have the folder /etc/envdir/app and this folder contains the file MYSQL_CONN_URI with a database URL inside of it. Just like this one here: mysql://root:secret@localhost:3306/mydb.

To read that directory and load the variable properly, you just have to do the following:

>>> from envelop import Environment
>>> env = Environment.from_folder('/etc/envdir/app')
>>> uri = env.get_uri('MYSQL_CONN_URI')
>>> uri.host
'localhost'
>>> uri.port
3306
>>> uri.user
'root'
>>> uri.password
'secret'

Hacking on it

Install dev dependencies

pip install -r requirements-dev.txt

Run tests

make test

Change it

Make sure you write tests for your new features and keep the test coverage in 100%

Release it

After you already made your commits, run:

make release

follow the instructions and do the harlem shake

Project history

This project was started by Lincoln de Sousa and was called "Milieu". We renamed it to "Envelop" on May 21st, 2014.