Skip "Installing dependencies with npm" step when pushing a Node.js app to Heroku

Question

Running git push heroku master always triggers a step that prompts:

Installing dependencies with npm

This step loads and reinstalls all of the dependencies again even it already exists. This is very time consuming and I want to skip this step sometimes when I deploy that I know the dependencies are the same.

Is there any command or options that do this?

Answer 1

Its been a long time since you asked this question, now the Heroku buildpack caches node_modules, so install times will be much faster.

If however you still want to block npm install, here is one solution.

As of when I write this, the default Heroku build pack does not allow skipping npm install entirely. You can see in the dependencies.sh file, this line will always run:

npm install --unsafe-perm --userconfig $build_dir/.npmrc 2>&1

However, if you create a file called .npmrc in your project folder with the following contents:

dry-run

This will cause npm install to not modify your existing node_modules directory.

Note that this change will also apply to the npm prune command that Heroku runs, but WILL NOT apply to the npm rebuild command (which is probably fine).