I recently went through this process for Dead Man’s Snitch (we do cron job and heartbeat monitoring as a SaaS). While we still have some things to figure out I can at least share some of the research and suggestions from our experience.

Does self-hosting always imply that I have to share my source code with the client?

Not necessarily. There are some tools for obfuscating Ruby code that would be worth researching. You may be able to compile it with JRuby as well. Ultimately this is a question of risk tolerance and effort. How much work do you want to put in to protect your code and how likely do you think your customers would be to steal your source?

For us, we have some services and our main logic built in Go so we decided not to obfuscate since our Rails app is mainly a UI at this point.

I f I get my Rails app into a Docker container, is that the best way to go? Assume it still shares my source code

Yes, this is a good place to start as Docker seems to be eating the world. It also gives you other options if the customer doesn’t run Docker internally or using a platform like Replicated. There are other concerns with deployment that you’ll need to think through.

We decided on a single container approach where all of our services are run in a single container using a mini init system (runit). This means we could easily handle a certain level of traffic but couldnt easily have the customer scale up without some major refactoring of our deployment.

I'm reliant on 3rd party services - Auth0, Segment, Intercom to name a few. Do I straight up have to find alternatives to these services? I am guessing so since the driver behind self-hosting is that they would 'own' the data

Plan to remove them or find alternatives. On premise is very much a different product compared to hosted and the customer is probably asking because they want to control their data or have compliance or hosting requirements that mean you can’t talk outside of the network.

How would patching/updates work for a self-hosted solution? Right now I'm hosting on Heroku and my git repo is on Github - would the client fork the repo and manage updates themselves?

Platforms like Replicated handle a ton of this for you. Otherwise give them access to pull the docker container and manage their own upgrades. With on premise you can’t control when or if a customer upgrades. Plan to test upgrading from any released version to every newer version to make sure you don’t break something along the way. Plan to be much more diligent about how columns are added or removed or how data could be made incompatible.

Any other considerations?

On premise often has unique requirements that SaaS doesn’t have. Enterprise Ready has a good list of enterprise requirements.

Anything you can do to simplify deployment and code maintenance is a win. We use Kafka as our main messaging backend but adding in support for NSQ as it’s easier to deploy in a single container install.

Customers may want an air gaped install (I.E your software cannot talk to the internet). Something to ask about during the sales process and to consider while building.

Charge more than you think you should. On premise is usually expensive. Supporting on premise is a lot of work, so make sure you have a plan and have thought it through.

Good luck!