README.md

Heroku Buildpack for Node.js

This is the official Heroku buildpack for Node.js apps.

Documentation

For more information about using this Node.js buildpack on Heroku, see these Dev Center articles:

• Heroku Node.js Support
• Getting Started with Node.js on Heroku
• Troubleshooting Node.js Deploys

For more general information about buildpacks on Heroku:

• Buildpacks
• Buildpack API

Locking to a buildpack version

In production, you may want to lock dependencies - including buildpacks - to a specific version.

First, find the version you want from the list of buildpack versions. Then, specify that version with buildpacks:set:

heroku buildpacks:set https://github.com/heroku/heroku-buildpack-nodejs#v170 -a my-app

If you have trouble upgrading to the latest version of the buildpack, please open a support ticket at help.heroku.com so we can assist.

Chain Node with multiple buildpacks

This buildpack automatically exports node, npm, and any node_modules binaries into the $PATH for easy use in subsequent buildpacks.

Feedback

Having trouble? Dig it? Feature request?

• help.heroku.com
• @adamzdanielle
• GitHub issues

Development

Prerequisites

For local development, you may need the following tools:

• Docker
• Go 1.14
• upx

Deploying an app with a fork or branch

To make changes to this buildpack, fork it on GitHub. Push up changes to your fork, then create a new Heroku app to test it, or configure an existing app to use your buildpack:

# Create a new Heroku app that uses your buildpack
heroku create --buildpack <your-github-url>

# Configure an existing Heroku app to use your buildpack
heroku buildpacks:set <your-github-url>

# You can also use a git branch!
heroku buildpacks:set <your-github-url>#your-branch

Downloading Plugins

In order to download the latest plugins that have been released, run the following:

plugin/download.sh v$VERSION

Make sure the version is in the format v#, ie. v7.

Tests

The buildpack tests use Docker to simulate Heroku's stacks.

To run the test suite:

make test

Or to just test a specific stack:

make heroku-16
make heroku-18
make heroku-20

The tests are run via the vendored shunit2 test framework.

Debugging

To display the logged build outputs to assist with debugging, use the "echo" and "cat" commands. For example:

test() {
  local log_file var

  var="testtest"
  log_file=$(mktemp)
  echo "this is the log file" > "$log_file"
  echo "test log file" >> "$log_file"

  # use `echo` and `cat` for printing variables and reading files respectively
  echo $var
  cat $log_file

  # some cases when debugging is necessary
  assertEquals "$var" "testtest"
  assertFileContains "test log file" "$log_file"
}

Running the test above would produce:

testtest
this is the log file
test log file

The test output writes to $STD_OUT, so you can use cat $STD_OUT to read output.