Ensure required environment variables are set when booting up Rails. https://boringrails.com/tips/ensure-rails-env-vars

01_ensure_environment.rb

# config/initializers/01_ensure_environment.rb

if Rails.env.development?
  %w[
    AWS_ACCESS_KEY_ID
    AWS_SECRET_ACCESS_KEY
    S3_BUCKET
    ALGOLIA_ID
    ALGOLIA_API_KEY
    ALGOLIA_SEARCH_KEY
    ALGOLIA_INDEX
    ALGOLIA_CAMPAIGN_INDEX
    TWITTER_API_SECRET
    TWITTER_API_TOKEN
  ].each do |env_var|
    if !ENV.has_key?(env_var) || ENV[env_var].blank?
      raise <<~EOL
      Missing environment variable: #{env_var}

      Ask a teammate for the appropriate value.
      EOL
    end
  end
end