denv

Run your script with your env

Ultra simple runner that injects vars from the implicit .env file into your commands of choice.

denv COMMAND [ARGS]

Expects a .env file in the current directory of format:

KEY=VALUE
FOO=BAR
AGE=29
host=hostname=foo user=bar password=false

Examples

Create an .env file holding your vars

$ cat .env
CONNECTION_STRING=host=foo user=bar password=baz

Use them in posix commands:

$ denv env | grep CONNECTION_STRING
host=foo user=bar password=baz

Use them when running python scripts:

$ denv python -c 'import os;print(os.environ["host"])'
foo user=bar password=baz

Why?

At Trustpilot we strictly follow the 12-factors of designing software-as-a-service apps, especially the concept of isolating your configuration outside your app.

Using environment vars is the accepted practice for injecting these configs into apps during deployment. But running locally i wanted something very simple to inject these env-vars into the runtime myself.

Looking around you will quickly find many implementations:

• https://direnv.net/
• https://github.com/bkeepers/dotenv
• https://github.com/motdotla/dotenv
• https://github.com/pedroburon/dotenv
• https://github.com/josegonzalez/php-dotenv

But i tend to disagree with them in two ways:

1. They tend to aim for being a replacement for your runtimes default environment lib and just overload with reading from a file
2. Some of them lack support for connection-strings where there can be many ='s per line.

I wanted to seperate it completely so the runtime only cared about env-vars and its standard way of accessing these, and then have the runner inject these vars as the only thing it did.

- sloev