ENVied

Canonical Repository: https://gitlab.com/envied/envied/tree/master#envied

TL;DR ensure presence and type of your app's ENV-variables.

For the rationale behind this project, see this blogpost.

Features

• check for presence and correctness of ENV-variables
• access to typed ENV-variables (integers, booleans etc. instead of just strings)
• check the presence and correctness of a Heroku config

Non-features

• provide or load ENV-values

Contents

• Quickstart
• Installation
• Configuration
  • Types
  • Key alias
    • env-type
  • Groups
• Command-line interface
• Best Practices
• FAQ
• Testing
• Development
• Contributing

Quickstart

1) Configure

After successful installation, define some variables in Envfile:

# file: Envfile
variable :FORCE_SSL, :boolean
variable :PORT, :integer

2) Check for presence and coercibility

# during initialization
ENVied.require

This will throw an error if:

• one of ENV['FORCE_SSL'], ENV['PORT'] is absent.
• or: their values cannot be coerced (resp. to boolean and integer).

3) Use coerced variables

Variables accessed via ENVied are of the correct type:

ENVied.PORT # => 3001
ENVied.FORCE_SSL # => false

Installation

Add this line to your application's Gemfile:

gem 'envied'

...then bundle:

$ bundle

...then for Rails applications:

$ bundle exec envied init:rails

...or for non-Rails applications:

$ bundle exec envied init

Configuration

Types

The following types are supported:

• :array (e.g. 'tag1,tag2' becomes ['tag1', 'tag2'])
• :boolean (e.g. '0'/'1', 'f'/'t', 'false'/'true', 'off'/'on', 'no'/'yes' for resp. false and true)
• :date (e.g. '2014-3-26')
• :env (similar to :string, but accessible via ENV - see Key alias for details)
• :float
• :hash (e.g. 'a=1&b=2' becomes {'a' => '1', 'b' => '2'})
• :integer
• :string (implied)
• :symbol
• :time (e.g. '14:00')
• :uri (e.g. 'http://www.google.com' becomes result of URI.parse('http://www.google.com'))

Key alias (unreleased)

By default the value for variable FOO should be provided by ENV['FOO']. Sometimes though it's convenient to let a different key provide the value, based on some runtime condition. A key-alias will let you do this.

Consider for example local development where REDIS_URL differs between the development and test environment. Normally you'd prepare different shells with different values for REDIS_URL: one shell you can run tests in, and other shells where you'd run the console/server etc. This is cumbersome and easy to get wrong.

With a key alias that's calculated at runtime (e.g. Rails.env) you'd set values for both REDIS_URL_TEST and REDIS_URL_DEVELOPMENT and the right value will be used for test and development.

Full example:

# file: Envfile
key_alias! { Rails.env }

variable :REDIS_URL, :uri

Source the following in your environment:

# file: .envrc
export REDIS_URL_DEVELOPMENT=redis://localhost:6379/0
export REDIS_URL_TEST=redis://localhost:6379/1

Now commands like rails console and rails test automatically point to the right redis database.

Note that ENV['REDIS_URL'] is still considered but REDIS_URL_<key_alias> takes precedence.
Also: any truthy value provided as key_alias is converted to an upcased string.
Finally: this setting is optional.

env-type (unreleased)

Variables of type :env take the key alias into account when accessing ENV['FOO'].

Say, your application uses ENV['DATABASE_URL'] (wich you can't change to ENVied.DATABASE_URL). Normally this would mean that the key alias has no effect. For env-type variables however, the key alias is taken into account:

# file: Envfile

key_alias! { Rails.env }

variable :DATABASE_URL, :env

The following now works:

$ DATABASE_URL_DEVELOPMENT=postgres://localhost/blog_development rails runner "p ENV['DATABASE_URL']"
"postgres://localhost/blog_development"

Note: this also works for ENV.fetch('FOO').
Also: no coercion is done (like you would expect when accessing ENV-values directly).

This means that for Rails applications when you set values for DATABASE_URL_DEVELOPMENT and DATABASE_URL_TEST, you no longer need a config/database.yml.

Groups

Groups give you more flexibility to define when variables are needed. It's similar to groups in a Gemfile:

# file: Envfile
variable :FORCE_SSL, :boolean

group :production do
  variable :SECRET_KEY_BASE
end

group :development, :staging do
  variable :DEV_KEY
end

# For local development you would typically do:
ENVied.require(:default) #=> Only ENV['FORCE_SSL'] is required
# On the production server:
ENVied.require(:default, :production) #=> ...also ENV['SECRET_KEY_BASE'] is required

# You can also pass it a string with the groups separated by comma's:
ENVied.require('default, production')

# This allows for easily requiring groups using the ENV:
ENVied.require(ENV['ENVIED_GROUPS'])
# ...then from the prompt:
$ ENVIED_GROUPS='default,production' bin/rails server

# BTW the following are equivalent:
ENVied.require
ENVied.require(:default)
ENVied.require('default')
ENVied.require(nil)

Command-line interface

For help on a specific command, use envied help <command>.

$ envied help
Commands:
  envied check                   # Checks whether you environment contains required variables
  envied check:heroku            # Checks whether a Heroku config contains required variables
  envied check:heroku:binstub    # Generates a shell script for the check:heroku-task
  envied extract                 # Grep code to find ENV-variables
  envied help [COMMAND]          # Describe available commands or one specific command
  envied init                    # Generates a default Envfile in the current working directory
  envied init:rails              # Generate all files needed for a Rails project
  envied version, --version, -v  # Shows version number

Best Practices

Some best practices when using ENVied or working with env-configurable applications in general.

include a .envrc.sample

While ENVied will warn you when you start an application that is 'under-configured', it won't tell users what good default values are. To solve this add a file to the root of your project that contains sane defaults and instructions:

# file: .envrc.sample
# copy this file to .envrc and adjust values if needed
# then do `source .envrc` to load

export DATABASE_URL=postgres://localhost/blog_development
# export FORCE_SSL=true # only needed for production

# you can find this token on the Heroku-dashboard
export DEPLOY_TOKEN=1234-ABC-5678

let direnv manage your environment

direnv will auto-(un)load values from .envrc when you switch folders.

As a bonus it has some powerful commands in it's stdlib.
For example:

# this adds the project's bin-folder to $PATH
PATH_add bin
# so instead of `./bin/rails -h` you can do `rails -h` from anywhere (deep) in the project

# the following will use the .envrc.sample as a basis
# when new variables are introduced upstream, you'll automatically use these defaults
if [ -f .envrc.sample ]; then
  source_env .envrc.sample
fi
...your overrides

# a variant of this is source_up
# an .envrc in a subfolder can load the .envrc from the root of the project and override specific values
# this would allow e.g. for a specific test-environment in the subfolder:
# in my-project/test/.envrc
source_up .envrc
export DATABASE_URL=the-test-db-url

FAQ

How to find all ENV-variables my app is currently using?

$ bundle exec envied extract

This comes in handy when you're not using ENVied yet. It will find all ENV['KEY'] and ENV.fetch('KEY') statements in your project.

It assumes a standard project layout (see the default value for the globs-option).

How to check the config of a Heroku app?

The easiest/quickest is to run:

$ heroku config --json | bundle exec envied check:heroku

This is equivalent to having the heroku config as your local environment and running envied check:heroku --groups default production.

You want to run this right before a deploy to Heroku. This prevents that your app will crash during bootup because ENV-variables are missing from heroku config.

You can turn the above into a handy binstub like so:

$ bundle exec envied check:heroku:binstub
# created bin/heroku-env-check

This way you can do stuff like:

$ ./bin/heroku-env-check && git push live master

What happened to default values??

The short version: simplicity, i.e. the best tool for the job.

In the early days of ENVied it was possible to provide default values for a variable.
While convenient, it had several drawbacks:

• it would introduce a value for ENVied.FOO, while ENV['FOO'] was nil: confusing and a potential source of bugs.
• it hides the fact that an application can actually be configged via the environment.
• it creates an in-process environment which is hard to inspect (as opposed to doing printenv FOO in a shell, after or before starting the application).
• there are better ways: e.g. a sample file in a project with a bunch of exports (ie export FOO=sane-default # and even some documentation) that someone can source in their shell (see Best Practices).
• made the code quite complex.

As an alternative include a file .envrc.sample in the root of your project containing default values (ie export FOO=bar) that users can source in their shell. See also Best Practices.

Development

$ ./bin/setup

# run tests
$ ./bin/rspec

# hack with pry
$ ./bin/console

# run CLI:
$ ./bin/envied

There's a .envrc.sample included that can be used in combination with direnv.

Contributing

To suggest a new feature, open an Issue before opening a PR.

1. Fork it: https://gitlab.com/envied/envied/-/forks/new
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Create a new pull request for your feature branch