Configuration overview

You can configure the New Relic Ruby agent with settings in a configuration file, environment variables, or programmatically with server-side configuration. This document summarizes the configuration options available for the Ruby agent.

If the default value for a configuration option is (Dynamic), this means the Ruby agent calculates the default at runtime. The value for the config setting defaults to the value of another setting as appropriate.

Configuration methods and precedence

The primary (default) method to configure the Ruby agent is via the configuration file (newrelic.yml) in the config subdirectory. To set configuration values using environment variables:

1. Add the prefix NEW_RELIC_ to the setting's name.
2. Replace any periods . with underscores _.

You can also configure a few values in the UI via server-side configuration.

The Ruby agent follows this order of precedence for configuration:

1. Environment variables
2. Server-side configuration
3. Configuration file (newrelic.yml)
4. Default configuration settings

In other words, environment variables override all other configuration settings and info, server-side configuration overrides the configuration file and default config settings, and so on.

View and edit config file options

The Ruby agent's newrelic.yml is a standard YAML configuration file. It typically includes a Defaults section at the top, plus sections below for each application environment (Development, Test, Staging, and Production).

The Ruby agent determines which section of the newrelic.yml config file to read from by looking at certain environment variables to derive the application's environment. This can be useful when you want to use info for the log_level config setting in your production environment, and you want more verbose log_level config settings (such as debug) in your development environment.

Here is an example newrelic.yml config file:

common: &default_settings
  license_key: 'YOUR_LICENSE_KEY'
  app_name: 'My Application Name'
production:
  <<: *default_settings
  log_level: info
development:
  <<: *default_settings
  log_level: debug

The Ruby agent looks for the following environment variables, in this order, to find the application environment:

1. NEW_RELIC_ENV
2. RUBY_ENV
3. RAILS_ENV
4. APP_ENV
5. RACK_ENV

If the Ruby agent doesn't detect values for any of those environment variables, it will default the application environment to development and read from the development section of the newrelic.yml config file.

When running the Ruby agent in a Rails app, the agent first looks for the NEW_RELIC_ENV environment variable to find the application environment and which section of the newrelic.yml to use. If NEW_RELIC_ENV is not present, the agent uses the Rails environment (RAILS_ENV).

When you edit the config file, be sure to:

• Indent only with two spaces.
• Indent only where relevant, in sections such as error_collector.

If you do not indent correctly, the agent may throw an Unable to parse configuration file error on startup.

To view the most current list of available Ruby agent configuration options, use the rake newrelic:config:docs command. This document describes the most common options.

Update the config file

This documentation applies to the Ruby agent's latest release. For details on earlier versions, refer to the comments in newrelic.yml itself.

To update newrelic.yml file after a new release, use the template in the base directory of the agent gem. When you update to new gem versions, examine or diff config/newrelic.yml and newrelic.yml in the installation directory to take advantage of new configuration options.

Settings reference

All configuration settings are documented in the sub-pages below. Each setting shows its type, default value, and environment variable equivalent.