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Comment by alin23 | Hacker News Reader

I did the licensing server for Lunar (https://lunar.fyi/) in Crystal.

It’s been a joy to work with it! The standard library for working with strings, JSON, YAML and XML is top notch. Type safe and extremely fast, very important characteristics for a licensing server that is queried hundreds of times a second.

I used the super simple Kemal HTTP server library which I like for APIs where most of the logic happens on the backend.

I have 8 years of experience as a Python developer and 5 as a Swift developer but after all that time I still like the terseness and type inference of Crystal.

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Crystal is great!

After ~10 years with Ruby, I decided to try out Crystal for my latest weird hobby project (a modern style bbs) and I have enjoyed it so much!

Considering the relatively short lifespan of Crystal, I was positively surpriced how good the documentation was and how fast, easy and stable the language it already is :)

Did you know Ruby before learning Crystal? I've been looking into it on and off, but it seems the documentation is mostly written as an "on top of Ruby docs" thing, as in it seems to assume you mostly already know the Ruby way of doing things and mentions only where things are different. That makes it harder to figure things out in the language, having to search the Crystal docs and then Ruby docs and figure out which one applies where. (I mean this for the very basic syntax and semantics of the language, nothing fancy yet.)

I didn’t know Ruby, and yes, some things had to be figured out through old Ruby knowledge. But that wasn’t as much of a barrier.

Every language that gets a little creative will have these features that you probably never saw, have no idea what to do with them and when is a best practice to use them.

Things like fibers, or the ways to do iteration without a for-loop, or the do…end closure syntax. They’re new and weird for non-Ruby devs, but they have their advantages, and you just have to try and use them a few times and they’ll become as common as your previous language.

I recently tried out Crystal (on a project that went nowhere very quickly) and liked what I got out of it. However, I feel the language is very complex in terms of operators and language constructs and found myself quickly completely forgetting language features even exist. There's a balance somewhere of "neatly fitting in your head" and "too simple" and Crystal firmly falls in the former for me.

Yes, the language is definitely much more complex than I expected. I’m still getting the hang of some syntax choices like the `with … yield` and the myriad ways of using closures: https://crystal-lang.org/reference/1.3/syntax_and_semantics/...

But I really miss some of Crystal’s features in other languages I work with:

1. Being able to declare union types when ingesting some not-so-normalized data

    alias UserID = String | Int32 | UUID

2. Macros and meta-programming

For example here I have a `storedprop` macro which I can use to define propertied that get saved automatically to a YAML config when they are changed: https://f.lunar.fyi/uRW69B/settings.cr

  class Settings
    include YAML::Serializable

    storedprop host : String = "ddcutil-server.local"
    storedprop port : UInt16 = 3485
  end

The good thing is you’re not really required to learn this stuff if you don’t want. But they surely can make the language fit to your style better if you invest the time to understand them.

Can I ask 2 questions?

1) Would you consider open sourcing the licensing server in Crystal? 2) What's your revenue with Lunar? :)

Thanks!

1. Yes, I’ve been working on generalizing the Lunar specific code for open sourcing it next month. Still WIP because I’m still getting busy with new monitor edge cases.

Last month I’ve also found out about Keygen (https://keygen.sh/) which has a really nice offering, and I would have probably chosen it instead of building my own solution if I’d known about it. I’m concerned about uptime with my own solution, I don’t have the means to provide enough redundancy in case of a network or data center failure.

2. I’m earning about $3.5k per month on Lunar Pro licenses (on average, some months can be 5-6k, some 2k). Doing quality macOS apps is a nice market to be in. You get to do tools for your own usage and also share them with others for some side revenue.

I’ve also created The low-tech guys (https://lowtechguys.com/) and each new app published there is also bringing about $200-$600 per month.

Little by little, I’m hoping to get to a continuous revenue of $8k per month so I can build a home for my family and have more time to pursue my other hobbies (woodworking: https://reddit.com/r/DIY/comments/t1l4rk/_/hyhvjix/?context=...) and (instrumental music: https://soundcloud.app.goo.gl/Dv8AT2JgNWrzFtLa8)

You sir are a big inspiration to me! As someone also born in EE I can very much appreciate your courage and dedication doing a side gig like this.

I would say 3500 a month is even a median salary for an IT position in WE. From your resume I take it you still work full time? I wonder if that's even worth it at this point unless you make a lot more from your FTE position.

Anyway props!

Thank you for the kind words! I haven’t updated my resume for a while because I don’t have a job anymore and I’m serious about not having to get hired ever again.

I’ve written about how I quit my job in March last year and started turning Lunar into a revenue generating project here: https://alinpanaitiu.com/blog/journey-to-ddc-on-m1-macs/

There’s a lot more info in the article that you might not be interested in though. For the 1 year anniversary of this decision I’m writing another article with everything I tried with Lunar and other apps in the last year. That might be more relevant because I’ll share user stats, real numbers on revenue, trial and error with paid advertising etc.

Yes, $3.5k sounds pretty good for Eastern Europe, but the truth is that prices have also skyrocketed. I’ve been trying to get away from my current matchbox sized rented apartment and build a house with my wife. I’ve reached the conclusion that I need like $200k in savings to do it and I’m nowhere near that.

I know it's an interesting problem and you probably learned a lot along your way but dont you feel like it was a hard problem to tackle and the ROI is rather low?

Oh no, not at all!

Sure, dealing with the problems of less knowledgeable users is sometimes annoying, because 99% of the problems stem from non-compliant monitors/hubs/docks etc.

But nowadays I get weeks at a time where I can do 0 work on Lunar and dive into my own curiosities (that's how I got to the idea of lowtechguys.com), or simply go on multi-city long trips with my bike without thinking that I have to ask for time off from a boss.

I don't look forward to being forced into long video calls where my time is simply wasted so that higher-ups can hear me saying "we're working on it".

The ROI is much higher than you think, time is far more valuable than money.

Founder of keygen.sh here. Thanks for the mention. Bummer you didn't know of it before, but I'm really working on improving SEO so hopefully that'll change for the next person. I actually checked out the source code for Lunar awhile back while digging around seeing how devs use Sparkle, since I've been working on an integration there for auto upgrades, along with a Swift SDK. Let me know if you ever hit a point with your licensing server where you want to check Keygen out. I'd be happy to chat.

Also curious -- from your OP re: Crystal:

> It’s been a joy to work with it! The standard library for working with strings, JSON, YAML and XML is top notch. Type safe and extremely fast, very important characteristics for a licensing server that is queried hundreds of times a second.

You said you're doing ~$3.5k/mo in licenses for Lunar. Where's the licensing volume coming from here? Keygen handles licensing for hundreds of products and millions of devices and I very rarely hit 100 RPS even on a busy day, so kind of curious how your licensing is setup to produce that much volume. :)

Nice to meet you!

I’m already looking into using Keygen for my next non-AppStore app. I’ll definitely reach out if I have any concern. Although from what I saw, your site explains everything well, and the dev tier will be helpful in testing.

I’m not getting 100 RPS constantly. It happens rarely, mostly when releasing updates. When an update is detected, Lunar has to check if the period of free updates hasn’t ended. Then the server is contacted again when the new version is launched.

With 3000 pro users (some received licenses for free because they donated when Lunar was free), 100 RPS can happen for short bursts and the server has to cope well with this even if it happens rarely.

i love Crystal too!

one downside for me is the development speed, compile time is definitely noticeable if you come from an interpreted language

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