heroku: error Command "webpack" not found.

Hello,

I spent the day migrating an old rails 4 app with the gem react_rails to a new rails 5.1 app with webpacker.

Everything works perfectly well, except when I try to deploy the app on heroku.

[gauravtiwari]

@tchret Hey, did you move dependencies under devDependencies inside package.json?

@gauravtiwari: Hi, thanks for your answer.
I just did and I've always the same error when Webpacker start the compilation:

yarn run v0.22.0
error Command "webpack" not found.

[gauravtiwari]

@tchret Sorry, I should have been more clear. Basically all dependencies needs to live under dependencies key except webpack-dev-server. Also when deloying to heroku is it running yarn install? Could you please share full log please (atleast the relevant parts)?

Logs + package.json

@gauravtiwari Ok got it! I think it's good on this side (see gist)
there is no yarn install during the deployment

[gauravtiwari]

@tchret Ahh there we go - Are you using any heroku buildpacks?

@gauravtiwari No, nothing. Am i supposed to?

[gauravtiwari]

@tchret No, I was just checking if that's overriding the default one. The default ruby buildpacks now takes care of this with webpacker gem. BTW, could you please add these two buildpacks and try deploying again -

heroku buildpacks:add --index 1 heroku/nodejs
heroku buildpacks:add --index 2 heroku/ruby

@gauravtiwari: haaaa the nodejs one was missing :)
I guess it was because the production setup was an old one (created under rails 4)

Thank you so much man 🙏🏼

[gauravtiwari]

@tchret Great 👍 no worries, glad it's working

[gauravtiwari]

FYI - https://devcenter.heroku.com/changelog-items/1114

[gauravtiwari]

@tchret Hey, seems like I found the main issue - Do you a yarn binstub inside bin folder?

[gauravtiwari]

Seems like the yarn install task is invoked but there is no yarn binstub present since you were using Rails 4 earlier. Please regenerate them - bundle install --binstubs