Thomas Cannon

I went to Blue Ridge Ruby, and it was an excellent time! I'm extremely grateful there's a regional Ruby conference (only a 90-minute drive away!) with great speakers and great company to boot.

My apprentice, Josh O'Halloran, got a sponsorship ticket and was immediately welcomed by the community. After 12+ years as a Rubyist, I had forgotten just how quickly & warmly we embrace newcomers. It's something we should continually practice.

Also, we need to make weird projects again! Talking about _why, Tenderlove, conference talks of yore, and other watershed moments in the early days of Ruby made me realize that we've been so focused on legitimizing, optimizing, and working with Ruby that we've stopped making dumb, silly things. If there's one critical thing I took away from my time in Asheville among folks that use the language I love every day, it's that we are better when we're collectively goofing off.

That, and root beer taught me the importance of B2B sales.

I hope the people who invented zip ties are living a nice, comfortable life

tl;dr: The best combination of Hetzner's ARM servers and Crunchy Bridge's regions are:

• Hetzner: nbg1-dc3
• Crunchy Bridge:  AWS eu-central-1
• Benchmarks at the end of the post

I’ve been working on getting the first Practical Computer app out of beta (a dispatcher app for service companies). It, and the rest of our smaller apps, have the following constraints:

• Extremely shoestring budget. $30/month operating budget. Not much to work with!
• Since it’s production data, there’s responsibility for the data to be redundant, safe, and secure.

Given those, I ended up choosing Hetzner’s ARM servers, given the sheer power + cost combination (even with them being in the EU; and this is a US-based project).

I’ve had great experiences with the Crunchy Bridge team, and 18+ years of experience have taught me that I really want someone else to make sure the database is secure for me. So even though it’s 10% of my operating budget here, it’s worth it (because the database is the most crucial part of the app!).

The problem is that the app server & database are on two separate networks; I don’t get the benefit of an internal network, so I had to benchmark what combination of regions would work best.

The previous iteration was completely misconfigured: Hetzner’s Helsinki region for the app, AWS eu-north–1 for Crunchy Bridge. This turned out to be awful for performance. After some benchmarking and experimenting, I found that the following combination gets pretty dang close to good performance given the constraints:

• Hetzner: nbg1-dc3
• Crunchy Bridge: AWS eu-central–1

(I’ve got benchmarks at the end of the blog post, don’t worry!)

Lessons learned

I wanted to write this not only to help other folks find the best combination easily; but to talk about the mistakes I made and lessons I learned.

• Mistake: I should have benchmarked different options & done more research. My first Crunchy Bridge cluster was actually in eu-central–1 , with the Hetzner server in Helsinki; and if I’d benchmarked & explored my options I would have avoided an unnecessary database migration.
• Win: When spooling up the Hetzner server, I did my best to use Ansible to provision the server, and use Dokku for a PaaS-like experience. This made it so that spooling up a new server in nbg1-dc3 was significantly easier. This is why I advocate for “automate as you go”, especially for infrastructure.
• Win: choosing the right vendors. Hetzner allows me to quickly & cheaply spool up a small project, and having Crunchy Bridge’s support & their tooling made spooling up the replicas & promoting them dead-simple.

Alternative solves

To be clear, I had a few other options available to me, some of which I could still choose, and have implemented:

• Application-level caching: This is done, and basically a given for any production app. I ended up using Redis here.
• Making a read replica on the Hetzner instance; use that for reads (a heroically misguided, but technically feasible idea!)
• Move from Hetzner to AWS. This would only make sense for an app that’s actually generating the profit to justify the switch. It’s hard to bear Hetzner’s price & power combo here.
• Move the primary DB back to Hetzner (not ideal. Again, 18+ years of experience have taught me that I don’t want to manage a bunch of databases)

Benchmarks, as promised

# Benchmark script
# x.report("crunchy-eu-central") { ApplicationRecord.connected_to(role: :crunchy-eu-central){ Organization.first.onsites }}
# x.report("crunchy-eu-north-1") { ApplicationRecord.connected_to(role: :crunchy-eu-north-1){ Organization.first.onsites } }
hetzner-helsinki:~$ dokku run dispatcher
rails@aaaaaa:/rails$ ruby script/benchmarks/database_performance.rb
…
ruby 3.3.1 (2024-04-23 revision c56cd86388) +YJIT [aarch64-linux]
Warming up ————————————–
crunchy-eu-central     1.000 i/100ms
crunchy-eu-north-1     1.000 i/100ms
Calculating ————————————-
crunchy-eu-central      9.788 (±10.2%) i/s -     49.000 in   5.031111s
crunchy-eu-north-1     14.124 (± 7.1%) i/s -     71.000 in   5.045164s
Comparison:
crunchy-eu-north-1:       14.1 i/s
crunchy-eu-central:        9.8 i/s - 1.44x  slower
====================================================================================================================
hetzner-nuremberg:~$ dokku run dispatcher
rails@5e9d1df43591:/rails$ ruby script/benchmarks/database_performance.rb
…
ruby 3.3.1 (2024-04-23 revision c56cd86388) +YJIT [aarch64-linux]
Warming up ————————————–
crunchy-eu-central     1.000 i/100ms
crunchy-eu-north-1     7.000 i/100ms
Calculating ————————————-
crunchy-eu-central     20.452 (± 0.0%) i/s -    103.000 in   5.037650s
crunchy-eu-north-1     96.340 (± 2.1%) i/s -    483.000 in   5.016063s
Comparison:
crunchy-eu-north-1:       96.3 i/s
crunchy-eu-central:       20.5 i/s - 4.71x  slower
====================================================================================================================
/// Spot-check of query latency
hetzner-helsinki:~$ dokku run dispatcher
rails@aaaaaa:/rails$ bin/rails c
Loading production environment (Rails 7.1.3.2)
irb(main):001> 10.times { p Benchmark.ms{ ApplicationRecord.connected_to(role: :crunchy-eu-central){ Organization.first.onsites } } }
1637.3784099705517
103.8463581353426
106.55084392055869
105.82964192144573
102.70471591502428
102.40731597878039
107.70620591938496
112.95577604323626
111.48629407398403
105.25572090409696
=> 10
irb(main):002> 10.times { p Benchmark.ms{ ApplicationRecord.connected_to(role: :crunchy-eu-north-1){ Organization.first.onsites } } }
1040.9399520140141
72.33657804317772
73.68614105507731
77.82750786282122
75.32874401658773
73.2035799883306
77.43134815245867
72.01353716664016
71.68629695661366
74.11726214922965
=> 10
====================================================================================================================
hetzner-nuremberg:~$ dokku run dispatcher
rails@aaaaaa:/rails$ bin/rails c
Loading production environment (Rails 7.1.3.2)
irb(main):001> 10.times { p Benchmark.ms{ ApplicationRecord.connected_to(role: :crunchy-eu-central){ Organization.first.onsites } } }
846.7416610001237
54.84945299758692
56.269697000971064
55.53825500101084
54.511651000211714
54.32877099883626
57.52018099883571
59.374027001467766
63.36915899737505
55.06629299998167
=> 10
irb(main):002> 10.times { p Benchmark.ms{ ApplicationRecord.connected_to(role: :crunchy-eu-north-1){ Organization.first.onsites } } }
168.30048900010297
11.614236002060352
12.266477999219205
15.882210002018837
15.326369000831619
11.819797000498511
14.219884997146437
10.650393000105396
11.742956001398852
13.63104199845111
=> 10

Picked up the RadWagon over the weekend and have already checked off much of bike ownership: ✅ the gear I bought didn’t fit & have to reorder parts ✅ “it’ll just take a bit” maintenance turned into an hour+ and wheel disassembly to track down a mystery noise ✅ rained on the planned ride day ✅ immediately helped someone get their lost dog on my first test ride

One of the hardest parts of starting the codebase for the Practical Framework was the continual restraint I had to practice to do stuff that is boring & annoying, but I knew it needed full focus to get done right. Teams & Organizations were a prime example of that; because I knew academically that they should be an MVP feature

Frankly, it took like 1-2 months to get right; and slowed everything down. All boilerplate, nothing fun, no business logic. But imagine the sheer vindication felt when I got this email in the middle of one of the smallest betas I’ve ever worked on:

There is one thing I wanted to let you know, since I think [REDACTED] hasn’t spoken to you about this yet. […], is there a way that we can add a section to say which company has the job? So for example, I’ve been entering jobs for [X] but I know [REDACTED] wants to enter jobs into the dispatcher for [Y]

Teams/organizations are always always gonna show up

Ticket title: fix mobile layout

Finally got the copy “done” (in as much as anything is done on the web) for the Practical Computer site; and I’m really happy with how it all turned out! practical.computer

Famicom Disk System reproduction for transit cards from the Nintendo store in Kyoto + blank NFC Card + custom “meetup” landing page with contact form = digital business card for conferences.

They finally arrived & look great!