lein-with-env-vars

A Leiningen plugin for performing a task with environment variable settings loaded from project.clj

Installation

Add the following line into the :plugins vector of an appropriate profile.

Usage

First, add :env-vars map to specify the environment variable settings in your project.clj like the following:

(defproject foo-bar

  ...

  :env-vars {:ENV_VAR_FOO "foo/bar/baz"}

  ...  )

And then, run a task with with-env-vars to set the environment variables according to the settings:

$ lein with-env-vars repl
...
user=> (System/getenv "ENV_VAR_FOO")
"foo/bar/baz"
user=>

You can also specify a string or a vector of strings instead of a map to the :env-vars key. In that case, those will be interpreted as the name of files containing environment variable settings.

For instance, say you have a file named .env-vars whose content is as follows:

{:ENV_VAR_FOO "foo/bar/baz"}

And if you specify [".env-vars"] to the :env-vars key in project.clj, then lein with-env-vars repl will work exactly as the above example:

(defproject foo-bar

  ...

  :env-vars [".env-vars"]

  ...  )

Leiningen hooks

This plugin also provides Leiningen hooks to inject environment variables automatically.

To enable the hook, add leiningen.with-env-vars/auto-inject to :hooks key:

(defproject foo-bar

  ...

  :hooks [leiningen.with-env-vars/auto-inject]

  ... )

Once you specify the hook, no need to use the with-env-vars higher-order task explicitly. Every time you run a Leiningen task, the specified environment variables will be injected automatically.

Note This hook mechanism is useful, but could also be problematic in some cases. If the hook is enabled and a file name is specified to the :env-vars key, the hook always checks whether the file exists (and if not, it will fail) every time you run a Leiningen task.

See also the example project to see how to use the plugin in a practical project.

Why not use Environ?

Environ (or lein-environ) is another tool for managing environment settings.

Though it supports environment variables as one of its setting sources, Environ does NOT actually set environment variables when starting a task process. So, for example, if you want to use a library that requires a certain environment variable to be set, it wouldn't work suitably.

License

Copyright © 2016 OHTA Shogo

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.