How to deploy node app that uses grunt to heroku


I'm using grunt and also grunt plugins like grunt-contrib-copy, grunt-contrib-mincss (that listed as npm dependencies for my application).

Also I don't commit npm_modules folder and public folder, where all generated files are. And I can't figure out how to build my app (I have grunt build command) after deploy and setup my server (it's already looking for public folder).

I saw some stuff like grunt-heroku-deploy, but it seems me a bad idea to commit before upload. Maybe there are some gentle decisions... Any thoughts?

12/9/2012 12:30:18 PM

Accepted Answer

npm has a support for a postinstall step (among many others) that might be just what you're looking for.

The node.js heroku buildpack runs this command when you push to heroku to resolve build dependencies:

$ npm install --production

If you take a look at the npm documentation, you can setup a series of scripts to run either before or after anyone runs npm install for your package. It's configured in the scripts property of package.json. The scripts property allows to run custom scripts (including grunt) when certain things happen in a package's lifecycle.

For example, to echo some text and run the grunt command whenever anyone (including Heroku) runs npm install, add this to your package.json:

  "scripts": {
    "postinstall": "echo postinstall time; ./node_modules/grunt-cli/bin/grunt <your task name>"

Important caveats:

  • You might have to change the path to the grunt binary in the postinstall script, check the error output if the grunt command doesn't execute.
  • grunt and grunt-cli must be listed as a dependency in your package.json so it gets installed by Heroku. Listing them under devDependencies is not sufficient since Heroku won't install those. Also, note that Heroku won't install it as a global package so to execute it on Heroku you're going to have to use a relative path (as it is configured above).

If this doesn't work (you'll probably need to fiddle with the relative paths a bit), then you might want to consider writing your own custom buildpack for Heroku.


As of 0.4, the grunt package no longer contains the grunt binary, which is now part of the grunt-cli package. The answer has been updated to reflect this.

6/4/2014 6:23:12 PM

This looks like it will largely be solved when the Heroku Platorm API slug and release features make it into the mainline. At that point, you can build your code locally (or on a ci server), package it up and send it to heroku via an API call and release it from there.

This is still in the beta period and was only announced on December 19, 2013.

I was never super happy with how many people seemed ok with checking in your generated code into git or the NPM postinstall hook. :(

Plus from a philosophical stance, doing a build during a release is simply another potential failure point.

Just for fun: Since that's not finalized yet, here's a bash script I threw together you can use for the time being to build your code on a deployment branch, commit it, deploy it to heroku and then remove the deployment branch. (I really am not a fan of bash deployment scripts, so I'm really looking forward to the platform API additions)

set -e 

# Delete current deploy branch
git branch -D deploy
# Create new deploy branch based on master
git checkout -b deploy
# Grunt comands to build our site
grunt build:production
# the dist/ directory is in my .gitignore, so forcibly add it
git add -f dist/
git commit -m "Deploying to Heroku"
# Push it up to heroku, the -f ensures that heroku won't complain
git push heroku -f deploy:master
# Switch it back to master
git checkout master

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