Black Box Hosting vs. Glass Box Hosting: An Interview With Judoscale's Adam

Heroku’s value was super simple: git push and you get a URL. No server naming exercises, no AMIs to patch, no cluster ceremony. Buildpacks detected my Rails app and just… did the right thing.

I was building a product nights and weekends; I didn’t want to think about deployment or scaling. The black box let me ignore everything that wasn’t shipping. If I were starting that same kind of small, bootstrapped SaaS today, the black box still buys the same thing: focus.

Whole categories of work. TLS is handled. Rollbacks are boring and reliable. Runtime upgrades don’t feel like heart surgery. Logs show up where I expect them. Scaling from one dyno to a handful doesn’t require a new playbook. You do pay a tax for that, but you’re buying back time. For a solo dev or tiny team, that trade is almost always worth it early on. I just didn’t have that much time to spend.

I think the glass box is going to win if you really need portability and/or really specific resource granularity. Most of the glass-box options right now are built around, or at least support, Docker containers. Docker containers are sort of the common denominator between all of them. But that can be helpful because it means it’s easy to switch from one platform to another — you own the build script and take it with you. That leads to the second point. When you can switch providers fairly seamlessly, you can take advantage of whoever has the best price and/or resource tiers that your specific application needs. Just switch to another platform with your same Docker container and you’ll likely save some money.

Well, it’s more surface area. Images, volumes, networking, health checks — you own more of it. Day-2 operations take more intention. You can absolutely beat Heroku on cost and control, but you’ll pay for it in time. And everything I just described is probably all more time than I’d want to spend on production infrastructure when bootstrapping a new app. I have features I need to build for my customers! But it’s nice that these platforms and strategies are all available right now in case I did want, or need, to go that route.

That one’s changed a bit over time. I now avoid marketplace add-ons whenever I can. Judoscale is a direct customer for almost all of our services: Sentry for exceptions, Scout for monitoring, BetterStack for logs and uptime, etc. Two reasons for that, really. First, it’s usually cheaper. Second, it’s portable. When our third party services are separated from our compute, we don’t have to worry about moving them when we move our compute.

Same with databases: I want a third-party provider, be it CrunchyData, PlanetScale, Tiger Data, etc. The teams behind those database services only care about their database services. It’s not a side-product for them. The UI’s, metrics, and controls are way better than the bolted-on database services offered by most hosting providers.

I think it tends to add an account and a connection string. But at the same time, it removes a migration nightmare if you should ever want to move your compute. If compute and data are decoupled, you can move one without detonating the other. I think that’s worth it.

Granularity. The jump from a $50 dyno to a $250-ish dyno is harsh, and it’s often just to buy memory headroom. Fly/Render give you more intermediate steps. If you’re scaling on thin revenue—which is normal early on—it’s hard to justify that cliff. That’s the moment teams start looking over the fence.

No, it makes Heroku a great early choice and a question later. If you’re pre-revenue and traffic is modest, the black-box dividend (focus) is worth the tax. If you’re high-traffic/low-ARPU (Average Revenue Per User), the math flips fast. That’s when a glass-box platform’s pricing steps feel sane.

Call it whatever… It’s all compute. What I care about is: how much work do I have to do to set up and maintain it?

Heroku’s buildpack approach is still a great default for Rails. Docker is great for portability — especially on platforms that want you to bring an image. All that to say, I don’t obsess over containers or their construction; I optimize for how much developer energy managing them consumes.

Honestly I’m not sure. I really like the “cloud native buildpacks” that seem to be cropping up, and having moved Judoscale across Heroku, Render, Fly, Railway, and ECS, I’ll be the first to tell you that having a Docker file ready to go is extremely handy.

I’d probably recommend just keeping a Docker file ready even if you don’t use it. It feels like a good spare tire.

Two. First is compute granularity, which we already covered. Second: support and enterprise sales have a reputation for being slow and not particularly helpful. We run a small team and prefer transparent, self-serve pricing; I don’t want to talk to sales to get a number… I don’t want an enterprise contract to just use the service. Anecdotally, other teams have had rough experiences there. It’s not a deal-breaker for a small shop on self-serve, but it’s part of the picture.

I don’t have enough firsthand experience with Fly/Render support to compare. What I do know is that the product choices—granular compute, Docker-first—have reduced the number of times I’d need support in the first place.

My default choice is going to be to start on Heroku and optimize for time-to-first-dollar. I want to get the app built and delivering value as soon as possible, and I don’t want to waste time on infrastructure details. The only caveat there is if I know I’m going to have high traffic and thin margins from the start. In that case, I might choose Fly. Either way, the goal is to get to first-dollar fast.

Otherwise I’d unbundle my services: third-party, direct account for DB, logs, error-tracking, etc.

Finally, I’d take a strong stance of YAGNI around most scaling and infra concerns. I wouldn’t build for scaling issues I don’t have yet — I’d flip on a simple autoscaler (like Judoscale!) and move on to my next feature.

Oh, also, no Kubernetes. Hard line here. It’s way too much surface area and a waste of time for small teams just getting their footing.

That’s fine. Complexity makes us feel important as developers. It also makes us slow. Keep it simple until reality—paying customers, not theoretical scale—forces your hand.