How to install Node modules on app platform in Rails app

Posted October 8, 2020 3.9k views
Ruby on RailsNode.jsDigitalOcean App Platform

Hello. I’m evaluating the app platform to see if we can migrate our Ruby on Rails app to here from Heroku. I tried adding npm install as a build command, and I can see it output in the logs while building the app, but it doesn’t appear to be succeeding as we’re getting an error while precompiling assets. The missing asset is one that gets installed via npm. So, my question is: what is the “correct way” to do an npm install before a Rails app precompiles assets? Do I need to add commands to install nodejs and npm (I’ve tried this to no avail)? Thanks

edited by bobbyiliev

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2 answers

@vianettim 👋

The ruby/rails buildpack will automatically install node modules and run assets:precompile as part of the build process. Currently npm isn’t available by default in that image, just yarn for now, which we’re tracking internally and plan to address. In the meantime, if you need to interact with node, you should use yarn instead of npm.

Alternatively, if you need a more flexible or customized environment, you can build with a Dockerfile.

Thanks for using the App Platform — happy coding!

  • “The ruby/rails buildpack will automatically install node modules and run assets:precompile as part of the build process.”
    It doesn’t seem to be doing this for our app, considering we’re getting an error on precompile that it can’t find the assets that exist in package.json. I tried adding a yarn install to the build commands, but am unsure if it is actually doing anything, since there is no output from the command:

    | 13:00:42 => Configuring custom build command: yarn install
    | 13:00:42 => Configuring custom run command: bundle exec puma -C config/puma.rb
    | 13:00:43 => Running Buildpack detection
    | 13:00:43 
    | 13:00:43 heroku/ruby                 0.0.1
    | 13:00:43 digitalocean/ruby-appdetect 0.0.2
    | 13:00:43 digitalocean/procfile       0.0.3
    | 13:00:43 digitalocean/custom         0.1.0
    | 13:00:43 
    | 13:00:43 => Building Buildpack app
    | 13:00:43 
    | 13:00:43 -----> Installing bundler 2.0.2
    | 13:08:14        Bundle completed (444.37s)
    | 13:08:14        Cleaning up the bundler cache.
    | 13:08:16 -----> Installing node-v12.16.2-linux-x64
    | 13:08:23 -----> Detecting rake tasks
    | 13:08:39 -----> Preparing app for Rails asset pipeline
    | 13:08:39        Running: rake assets:precompile
    | 13:08:42        [tunemygc] not enabled
    | 13:08:51        Yarn executable was not detected in the system.
    | 13:08:51        Download Yarn at
    | 13:08:52        I, [2020-10-14T20:08:52.940164 #2415]  INFO -- : Writing /workspace/public/assets/disable_animations-876051af5339dca677a49984ab565dd4ea5242b646c43b3400b669ddf881688c.css
    | 13:08:52        I, [2020-10-14T20:08:52.942642 #2415]  INFO -- : Writing /workspace/public/assets/disable_animations-876051af5339dca677a49984ab565dd4ea5242b646c43b3400b669ddf881688c.css.gz
    | 13:08:53        I, [2020-10-14T20:08:53.633437 #2415]  INFO -- : Writing /workspace/public/assets/mailer-efd29798b355d7f1ac52cfd32cba0f064e3fbdfa8c2bf5adcc2682969b396bda.css
    | 13:08:53        I, [2020-10-14T20:08:53.634069 #2415]  INFO -- : Writing /workspace/public/assets/mailer-efd29798b355d7f1ac52cfd32cba0f064e3fbdfa8c2bf5adcc2682969b396bda.css.gz
    | 13:08:53        rake aborted!
    | 13:08:53        Sprockets::FileNotFound: couldn't find file 'croppie/croppie' with type 'application/javascript'

    Any ideas as to how to proceed, or would I need to switch to building with a Dockerfile?

I had the same issue and the same hypothesis. Upon further inspection, I noticed a tiny little error in the log.

error Your lockfile needs to be updated, but yarn was run with `--frozen-lockfile`.
info Visit for documentation about this command.

That’ll do it! I tried running yarn install --frozen-lockfile locally and, indeed, it failed. The digital ocean buildpack appears to continue building if that fails, though, and goes on to run rake assets:precompile.

The solution was to run yarn install locally, which updated yarn.lock, then redeploy.