Tip: Ensure required environment variables are set when booting up Rails
It’s common to use environment variables to configure external services or other options in a Rails app. These ENV_VARS usually are not checked into source control, but rather configured per environment.
Rails has the concept of initializers, which is code run during the boot phase of a Rails app.
You can add a custom initializer to check that required environment variables are set to avoid exceptions later on when your code expects a value to exist.
Usage
Create a new initializer in your app and add the required variables:
# 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
Options
Rails initializers are loaded and executed in alphabetical order. So use a name like 01_ensure_environment.rb to control the sort order and make sure this one loads first.
You may wish to check in a sample .env.sample file into git (without any values) to make it easier for new team members to get their environment into a working state.
Additional Resources
Rails Doc: Configuring Rails apps