Environator

About

Environator is a tool for running commands against specific environment variables, as per the 12-factor app model. Environment variables are specified via simple bash syntax profile files. Plus, you can import environment variables from outside environments like a Heroku app, which allows you to run local commands against the same configuration as your remotely deployed apps!

Installation

go get github.com/dailymuse/environator
pushd $GOPATH/src/github.com/dailymuse/environator
make install
popd

Example Usage

# All your profiles will be stored in the `env` directory
mkdir -p env

# Let's make an example profile
echo 'DATABASE_URL=postgres://user:pass@127.0.0.1:5432/db' > env/example_profile.env

# Now we can run a command against this profile. For example, to print the new value of DATABASE_URL:
e example_profile printenv DATABASE_URL

# Let's create a new profile, that inherits from `example_profile.env` and
# adds new environment variables:
echo '{{ source "example_profile" nil }}' > env/example_profile_2.env
echo 'REDIS_URL=redis://localhost:6379/0' >> env/example_profile_2.env

# Now we can use that file. Let's print the overall environment:
e example_profile_2 env

# Let's make a third profile, this time pulling from a Heroku app!
echo '{{ heroku "my_heroku_app_name" }}' > env/my_heroku_app_name.env

# At run-time, environator will import the environment variables from
# `my_heroku_app_name`; you can now print its env like so:
e my_heroku_app_name env

Profiles

You define profiles in the env directory of your project repo. Each profile is a simple bash file specifying environment variables to export.

Environator parses these profiles using golang's text/template library, so you can use that to add special logic to the profiles.

These functions are exposed for profiles:

• {{ source "profile_name" args }} - Imports the profile located at env/profile_name.env, passing in args as the template args.
• {{ heroku "app_name" }} - Imports the environment variables from the heroku app app_name.
• {{ vault "path/to/keys" }} - Imports all of the keys in a vault directory as environment variables. Note that you'll need existing environment variables defined either in the profile or elsewhere to configure the vault location and authorization.

These variables are additionally accessible for profiles:

• debug - Whether debug mode is enabled.
• dir - The directory from which the command will be executed.
• source - The profile that was passed into environator.
• cmd - The command name and arguments.

Because profiles compile to just bash, you can do arbitrary manipulation of environment variables. For example, at The Muse we use python with virtualenv and go. The profiles that are tied to our Heroku apps look something like this:

source venv/bin/activate
GOPATH=`pwd`/muselytics:$GOPATH
{{ heroku "app-name" }}

Then we simply store that in env/app-name.env, so that the Heroku app name is the same as the profile name.