Cheaply running ruby on rails apps (for side projects)

Alex Park — Mon, 02 Jan 2023 22:08:13 +0000

With Heroku's free tier gone, this is my work-in-progress configuration for a new ruby on rails apps that I want to run as cheaply as possible.

Here's the gist of it:

Rails.cache uses :file_store
Use SQLite for a database
Use redis for sidekiq and actioncable
Run Sidekiq in embedded mode
Use disk_storage for ActiveStorage
Run ActionCable's websocket server in embedded mode
Use hatchbox to deploy all of my apps on a single VPS on linode/vultr/aws/digital ocean
Use Cloudflare as a CDN

The main theme here is taking advantage of how cheap disk storage is on VPS providers (~$0.10 per GB) as well as Hatchbox allowing unlimited apps to be deployed on a single machine. The cost per months follows this formula:

cost = ($10 per server + VPS cost) / # of apps

So if I had 10 apps running a single $5 Linode server and each app would cost me $1.50 per month. 100 apps on a $40 server would cost my $50 / 100 apps = $0.50 per app.

Caveats

This stack does make some assumptions about the app ideas I have:

a lot of reads and very few writes
very small chance of going viral
low to medium traffic
wary of every gem you use to manage memory usage

And this stack does nudge coding your app a certain way to squeeze as many apps as possible in a single server:

heavily use russian doll caching
SQLite should be running in WAL mode
Sidekiq workers should not do anything that requires a lot of compute (adding things together, reading files, etc).
Remove cookies from page responses so that they can be cached in a CDN and use lazy turbo frames to fetch user specific content.

Possible further optimizations

This same configuration could be done on fly.io instances in addition to scaling down to 0 after hitting idle timeout. I learned about this here. Although I don't have a lot of experience optimizing rails boot times in order to respond to a waking request fast enough. Given what has happened to heroku, I'd bet that a simple VPS provider would outlast a niche platform-as-a-service.

If anyone is interested in a tutorial, let me know.
Thanks for reading!

I am partially running this stack (sqlite and file_store caching) in production today at reipricetracker. If you are concerned about performance, you can see the top left speed badge be adding ?rails=1 to any URL.

DEV Community: Alex Park

Cheaply running ruby on rails apps (for side projects)

Caveats

Possible further optimizations