validates against environment variables

Gemfile

source 'https://rubygems.org'

gem 'json-schema'

validates_env.rb

#!/usr/bin/env ruby

require 'bundler/setup' unless defined?(Bundler)
require 'json'
require 'json-schema'

schema = JSON.parse(DATA.read)
begin
  JSON::Validator.validate!(schema, ENV.to_h)
rescue JSON::Schema::ValidationError => error
  warn error.message
  exit 1
end

__END__
{
  "title": "Schema of some script's environment variables",
  "$schema": "http://json-schema.org/draft-06/schema#",
  "type": "object",
  "properties": {
    "DEBUG": {
      "type": "string",
      "enum": [
        "1",
        "0"
      ]
    },
    "LOGLEVEL": {
      "type": "string",
      "enum": [
        "0", "1", "2", "3", "4", "5", "6", "7"
      ]
    },
    "PLACK_ENV": {
      "type": "string",
      "enum": [
        "development", "test", "production"
      ]
    },
    "PATH": {
      "type": "string",
      "pattern": "[^:]+(:[^:]+)*"
    }
  },
  "required": [
    "PLACK_ENV"
  ]
}

✘╹◡╹✘ < ruby validates_env.rb
The property '#/' did not contain a required property of 'PLACK_ENV'
✘>﹏<✘ < PLACK_ENV=a ruby validates_env.rb
The property '#/PLACK_ENV' value "a" did not match one of the following values: development, test, production
✘>﹏<✘ < PLACK_ENV=development ruby validates_env.rb
✘╹◡╹✘ <