404human

Service Monitor build log M0 · 0.1

· 2 min read · experiment

Checkpoint 0.1: rules first, code second

An empty project sounds boring. It's also the cheapest moment to decide what the compiler should never let me do.

Goal
Set up the project, and the rules, before writing any real code.
Built
An empty project in nine parts, two pinned libraries, and rules the compiler enforces.
Result
0 warnings · unwanted code left out of the build entirely
Code
aca3990

Nobody gets excited about an empty project.

But it’s the cheapest moment to decide which mistakes you’ll never allow, because there’s no old code to clean up yet.

How I’m building this

Every milestone is cut into small checkpoints. A checkpoint only counts when:

  • its tests pass,
  • Rust’s strict code reviewer (a tool called clippy) has zero complaints,
  • it’s saved in git,
  • and it’s written up here, mistakes included.

What I built

  • An empty Rust project, split into nine parts: checking, scheduling, storage, alerts and so on. Each part has one sentence saying what it does, and what it must never touch.
  • Two libraries, pinned to exact versions: tokio, the engine that lets a program do many things at once, and reqwest, for making web requests.

The trick: leaving a feature out

On day 0 I found that the web library retries some failed requests by itself. There’s a setting to turn that off, and I’ll use it.

But settings get forgotten. So I also left out the part of the library where those retries live (HTTP/2, which a simple health check doesn’t need).

I checked the build afterwards: that code isn’t in there at all. It can’t misbehave if it doesn’t exist.

Rules the compiler now enforces

  • No unsafe code. Rust’s safety checks stay switched on everywhere in my code.
  • No unwrap() outside tests. That’s Rust’s “assume this worked, and crash if it didn’t”. A monitor should report a problem, not fall over.
  • A name-clash check. From my AI Rust exams: give a helper the same name as a built-in method, and Rust can quietly call the wrong one.

And one more choice: if a single check crashes, the monitor writes it down as a gap instead of taking the whole thing down with it.

Numbers

  • 16 seconds to build the web library and its encryption code, using just the standard compiler on this laptop.
  • 0 warnings. 0 tests, because there’s nothing to test yet.

What it doesn’t do yet

Nothing runs. This checkpoint is the foundation, and nothing more.

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