Hi! If you set NPM_CONFIG_PRODUCTION=true you should still only install production dependencies, even with NODE_ENV=staging

heroku config:set NPM_CONFIG_PRODUCTION=true

Yes but as I wrote in the description this changes the NODE_ENV, which has effects on the post build script, since the env will now always be production.

I find it a bit strange that the way to get not get dev dependencies is to overwrite the NODE_ENV, instead of just using the --production flag.

My team has also been having this issue as we have a staging dyno that builds our slug before we promote that slug to production. And we didn't want the devDependencies to be included in the slug, so we set NPM_CONFIG_PRODUCTION. But because of this our staging dyno is now being run with NODE_ENV=production, which is causing problems for us.

For now we've had to use a separate environment variable APP_ENV which we've set NODE_ENV to right after booting up.

I've looked through this repo and couldn't immediately find where/how the npm install command is run, but would it be possible to have an env variable that either sets NPM_CONFIG_PRODUCTION only on the install command, or maybe some sort of configuration for the install command itself?