UPDATE: I decided to leave my apps on Heroku, thanks to a convo I had with @zspencer. I've reproduced our conversation below - hope it helps someone!

ARIT: Hi Zee. You recently provided a beautifully-detailed answer to my devTo question about migrating Rails from Heroku to VPS. I built these Rails apps while in coding bootcamp; their storage is linked to AWS S3 buckets and my AWS free year is coming to a close. I'd like to migrate the apps so they can use local storage on the server. Although they are client-facing, they dont use up too many resources, so I figure hosting them all on the same VPS would save me a bit of money.
I followed Oliver's migration tutorial on GoRails.com today; I got through it okay, but upon loading the server's IP, I'm getting a error:

Error ID: 35090cd9
Details: Web application could not be started by the Phusion Passenger application server.

Don't know where to go from here, and my head hurts.

ZEE: Did you run the numbers to figure out how much S3 would cost if you left the apps on Heroku? I store a few gigabytes of data in S3 and it's pennies a month.
My guess is that you'll want to try and find the logs for nginx and/or phusion passenger to figure out why the application is refusing to start.
Further, there is a risk that if you rely on your server to provide storage capacity for your application, you no longer have the uptime and redundancy that S3 provides; s3 is a really good tool for storing files very very inexpensively and making sure that you can access it later.
If you do wind up storing the data on your web server, and then the web-server starts running out of space, you'll need to upgrade the storage capacity of the web-server, which will involve taking the server down for a period of time, duplicating the disk image, and re-inflating it on a larger virtual disk.
Also it's totally OK to ask these questions on devTo :) Someone else is probably in a very similar boat and would benefit from you exposing your uncertainty!

ARIT: You've convinced me Zee :) I'll stay with S3. I'll update my devTo post.

ZEE: I mean, I don't know if that's the right call, but I am supremely lazy and I'm happy to exchange dollars for time, especially if it's pennies on the hour or day.

ARIT: Lol. No, you've really convinced me - especially your argument about scaling. And you're right - S3 isn't that expensive for low storage use and queries. Plus, the process of migrating just 1 of my apps was so headache-inducing! 😫

ZEE: Wait until you have customers on the app and it goes down at 3am on a Tuesday and you thought adding a "call me when it goes down" alert was a good idea and you wake up to a phone screeching and you have to re-figure out what the hell is going on while groggy.

ARIT: 😆

Old Post Follows Below:

Hello DevTo Fam! I need some help.
I'd like to migrate my Rails apps from Heroku to a VPS on Vultr. There are several guides on how to do this for one Rails app. However, I would like to host all 5 of my apps on the same VPS, utilizing a name-based hosting approach to resolve all their domains. This is where I'm not finding much online that is helpful. One guide makes use of the Passenger server, but I understand that Puma is considered better. For a web server, I'm partial to Nginx.
I would really appreciate any help in mapping out how to accomplish this. Thank you so much in advance! 🙏🏾