by heroku

GitHub Readme.md


This buildpack sets up the necessary machinery to utilize Heroku's Language Metrics feature for Node.js applications.

What Node versions does it support

This buildpack supports all Node versions greater than 8.0.0. All 8.x, 9.x, and 10.x releases are supported.

Including this buildpack with an earlier version of Node will not break the application. It will simply become a no-op.

How does it affect my slug?

This buildpack does two things.

  1. Copies a Node.js module into the slug
  2. Copies a .profile.d/ script into your slug

When $HEROKU_METRICS_URL is set as a result of the runtime-heroku-metrics labs flag, the Node module will be automatically required by your Node app at runtime using the NODE_OPTIONS env var introduced in 8.0.0.

The Node module monitors your application's event loop and garbage collector and forwards metrics to $HEROKU_METRICS_URL for processing.

Future Plans

This buildpack is expected to be rolled into the official Node buildpack before Node metrics are GA.


This buildpack uses Hatchet to run integration tests. To run them locally make sure you have Ruby installed, then execute:

$ bundle install
$ bundle exec rspec

While it takes too long to run on Travis as part of CI, you can validate changes across every supported version of Node locally by running:

$ bundle install
$ TEST_ALL_NODE_VERSIONS=true bundle exec rspec