Working, non-working, Incremental Static Regeneration on Heroku

[u840903]

Hey!

I've got a project with incremental static regeneration. If I locally boot-up next using next start and hit the URL http://localhost:3000/products/123 the files /.next/server/pages/products/123.html and /.next/server/pages/products/123.json are created and everything feels nice and speedy.

If I deploy the very same application on Heroku and hit the URL http://my-app.heroku.com/products/123, login in to my environment using the heroku cli, heroku run bash, cd /.next/server/pages/products/ there are no files created, but it still feels nice and speedy.

Why is that?

1. Are the files created, but I can't see them?
2. Does Next use some kind of in-memory store if it does not have file-write-access?
3. Does ISR not work out-of-the-box on Heroku, but my server is fast enough anyway.
4. Should I use Vercel to get the most out of Next?

Thanks in advance,
Jan

[birdcar]

Hi @u840903 👋

The reason you're not seeing the files when you log into your environment using the Heroku CLI (my guess is using heroku run bash or something similar) is because all processes in a Heroku application run in their own Dyno, and each Dyno is a sandboxed container.

As a result, the files generated by your web process's Dyno are likely created just as you expect them to be, but you can't see them because when you run heroku run bash you actually spin up a totally separate Dyno that hasn't generated those files.

Hopefully that clarifies things!

[u840903]

Oh! I see. Thank you!