Of course the larger your project is, the more hassle, but that's not specific to Rails.
It is not simple. Python or Node.Js suffer the same issues, though.
Compared to dropping a go-binary or rust build somewhere and firing that up, Rails/Ruby (Rack, Sintra, Rails etc) are a mess.
In no particular order, the issues I had to deal with in the last three months:
* asset pipelines crashed randomly; turned out the ~2GB build VPS had too little memory to run the asset pipeline.
* puma and unicorn and phusion cannot be ran and configgured easily on one server.
* rbenv builds are hard to manage.
* getting the correct gems on your server is a mess. There is bundler, rbenv, vendored, rubygems.org, gem, Gemfile, Gemfile.lock, ruby-version in gemfile, ruby version .ruby-version, all of which can -and will- conflict at some point.
Add to that, that a typical Rails app requires at least redis, postgresql/mysql, quite some lib-x headers to build native gems, and imagemagick etc, and you have a very complex setup.
This isn't more complex than your typical Django, Laravel or ExpressJs setup. But it is far more complex than deploying a go, rust, or Java bundle.
I know things get simpler when you keep "one app/thread - one server". But price-wise that doesn't make sense, especially since many common Rails apps hardly run on a the cheapest VPS (a throttled dual-core 500MB server). If you run ten tiny services, ten servers add up quickly.
I also host some larger apps on their own server, some loadbalanced over multiple servers.
But throwing 10+ ruby services on a VPS is hard. Especially if you don't want to, or cannot constrain their ruby-versions, app-server, etc.
It is hard for the exact same reason why setting up a local env may be hard. I recently had to help a co-worker on an old MacOS machine who broke her entire mac-desktop because she installed RVM because somehow that was in the tutorial for getting the app locally.
Anything with a runtime is harder than anything without that runtime. This is too obvious, but does warrant some highlighting. Ruby's runtime is one of the hardest of all runtimes because it comes with so many moving parts. Python is a close second, and on Ubuntu (my main driver) probably worse than Ruby, because fing up Node is fine, but fing up Python can render your machine unusable, unrecoverable so without good understanding of all python things.
Some things I'd note-- * Don't use puma or unicorn. Phusion Passenger and Apache is just fine performance-wise and is much more robust IMO. * To avoid ruby version conflicts use .ruby_version as your sole source of versioning. I use this in all my Gemfiles: `ruby File.read('.ruby-version').strip` * RVM isn't as popular as rbenv but it's amazing and you won't run into the issues you mentioned. It integrates with Capistrano and Passenger+Apache really well. * 2GB might be a bit light for a production app even with light load. We start our new VMs at 8GB and then adjust up or down as makes sense.
We still do a single Ubuntu LTS VM for each app rather than anything fancy. Once you've added the stuff you need via apt it just works. Our sysops folks use Ansible playbooks that automate everything so there's no mystery when we need to do an OS upgrade or spin up a new VM.
And please don't try to tell us that a real-world Java web application is simpler than, well, anything. ;-)
Execjs, libreadline, libsqlite3, lib-postgres, (older)nokogiri etc. Quite a lot of the headers keep being a problem. Not major, often a mere ddg+apt-get away, but still annoying. It does get problematic when you have multiple apps depend on different libreadlines, for example.
And I'm not often deploying java, but at least the runtime and tooling has become omnipresent. The latest deploys were a mere "move all files there, and restart the service". With Rails you at least need to rebuild the gems.
Often java-services are an `apt get jenkins` away. There is no equivalent apt-get gitlab or apt-get mastodon that just sets up the stack entirely. But that is probably due to their popularity more than technology.
Tongue in cheek, but honestly, that's probably debatable.
Under the hood, Java apps (at least in my experience) are Eldritch horrors with hundreds of beans/proxies/servlets/God knows what, needless layers upon layers of abstractions and dangerous amounts of reflection and dynamic behavior, all to launch and initialize a web application in a "simple" manner. I've always seen the exact same horror, be it working with Spring Boot, Spring, JavaEE, Struts, or even something like Dropwizard (though it seemed a bit more sane). Only the microframeworks seemed decent in comparison, something like Vert.X (has a different paradigm, though), or Quarkus/Helidon.
But when it comes to running them... well, historically they were still a nightmare, if packaged with .war and relying on certain application servers/JDK versions being present. But packaging them as executable .jar files (think Spring Boot) makes them similarly easy to Go, at least as long as you have the JDK version that you need. You just drop the file in a folder and if you have some configuration (which your Go app would also need in one way or another), you can probably launch it.
> I have never had the sort of problems you say you're having trying to keep gems sorted.
Ruby suffers from the same problem that Python, Node, PHP and other non-statically compiled technologies suffer from - messing around with dependencies. If i develop on Ruby locally against version X.Y.Z, but only X.Y.W is available on the server due to Debian packaging older versions, then i'll run into problems because of the project refusing to build/run. I've also run into situations where building the native stuff (DB drivers in this case) will fail, for example, when libpq-fe.h headers were missing and pg couldn't been installed, so the gem native extension couldn't build. Also, on Windows, Ruby 2.7 downloaded the sqlite gem with 3 different trojans (Win64.Alien.eg, Win64.Alien.ef, Win32.Agent.xahigh) in the extensions (btreeinfo.dll, memstat.dll, memvfs.dll), as picked up by Kaspersky. No idea how that happened, or whether that could have been a false positive, but i didn't appreciate that much either.
That said, i have a folder that has about 112 images of all sorts of software breaking in various ways to date, and the number is only so low because i don't screenshot things on my work computer and not even every small instance of something breaking. In my experience, all of the technologies out there are bad in some ways, it's just about identifying and managing these tradeoffs towards whatever is suitable for your circumstances.
