New Relic example

newrelic.js

/**
 * New Relic agent configuration.
 *
 * See lib/config.defaults.js in the agent distribution for a more complete
 * description of configuration variables and their potential values.
 */
exports.config = {
  app_name: ['my application'],
  license_key: '<licenese key>', // only thing required (or set NEW_RELIC_LICENSE_KEY env variable)
  logging: {
    level: 'info'
  },
  agent_enabled: true,
  error_collector: {
    enabled: true,
    ignore_status_codes: [404, 405, 418]
  },
  process_host: {
    display_name: 'West 01' // give your server a name
  }
}

// for more options see:
// https://docs.newrelic.com/docs/agents/nodejs-agent/installation-configuration/nodejs-agent-configuration#exports_config

newrelic.txt

Install New Relic and add it to your package.json via:

npm i newrelic --save

In your app.js (your main js file) do:

require("newrelic")

Drop in the "newrelic.js" configuration file to the root of your project and the installed New Relic agent will do the rest. 

For more options and use cases you can see the agent's API: 
https://docs.newrelic.com/docs/agents/nodejs-agent/supported-features/nodejs-agent-api

error_collector.enabled is true by default