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This commit is contained in:
Joe Ardent
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title = "Hitman: another fine essential sundry service from Nebcorp Heavy Industries and Sundries"
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slug = "hitman"
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date = "2024-03-31"
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draft = true
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[taxonomies]
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tags = ["software", "sundry", "proclamation", "90s", "hitman", "web"]
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+++
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# Hitman counts your hits, man.
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Recently, someone in a community I'm part of asked the following:
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> I was thinking about how we used to have website hit counters in the 2000s and I was wondering --
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> has anyone put a hit counter on your personal website?
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## The dream
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Some people had, it turns out, but many had not. Among the had-nots was me, and I decided to do
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something about it. The bottom line up front is that you can see it in action right now at the
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bottom of this very page, and if you want, check out the code
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[here](https://git.kittencollective.com/nebkor/hitman); it's called Hitman!
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## The reality
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## What's the problem?
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Back in the day[^web1.0], there was basically only one way to have a website: you have a Linux box,
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running the Apache webserver, with PHP enabled, and a MySQL database to hold state; this is your
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classic LAPM stack, obviously. If this is your website, adding a visible counter is trivial: you
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just use PHP to do server side rendering of the count after a quick SQL query. And because this was
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basically the only way to have a website, lots of "website operators" put hitcounters on their site,
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because why not?
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But this is the year 2024, and we do things differently these days. This blog, for example, is built
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with a "static site generator" called [Zola](https://www.getzola.org/), which means that there's no
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server side rendering, or any other kind of dynamic behavior from the backend. It's served by a
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small Linux VPS that's running the [Caddy](https://caddyserver.com/) webserver, and costs about five
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bucks a month to run. If I wanted to have a hitcounter, I'd have to do something non-traditional.
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## What's the solution?
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For me, it turned out to be a sidecar microservice for counting and reporting the hits. As usual
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these days, my first instinct is to reach for [Axum](https://docs.rs/axum/latest/axum/), a framework
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for building servers in Rust, and to use [SQLite](https://sqlite.org/) for a database. Caddy proxies
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all requests to the hit-counting URL to Hitman, which is listening only on localhost.
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### That sounds simple
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Ha ha, it does, doesn't it? And in the end, it actually kinda is. But there are a few nuances to
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consider.
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### Privacy
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The less I know the better, as far as I'm concerned, and I didn't see any reason to know more than I
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already did with this, but I'd need to track the IP of the client that was doing the request in order to
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de-duplicate views. Someone linked to [this
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post](https://herman.bearblog.dev/how-bear-does-analytics-with-css/) about how the author uses a
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notional CSS load to register a hit, and also how they hash the IP with the date to keep the counts
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down to one per IP per day. They're doing quite a bit more actual "analytics" than I'm interested
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in, but I liked the other idea. They mention scrubbing the hashes from their DB every night in order to
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pre-emptively satisfy an overzealous GDPR regulator[^logs], but I had a better idea, which was to hash the
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IP+date with a random number that is not disclosed, and is regenerated every time the server
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restarts.
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I wound up [hashing with the date +
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hour](https://git.kittencollective.com/nebkor/hitman/src/commit/1617eae17448273114ca1b1d9277b3465986e9f1/src/main.rs#L79-L94),
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along with the page, IP, and the secret. This buckets views to one per IP per page per hour, vs the
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once per day from the bearblog.
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### Security?
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I spent some time on this, but ultimately realized that there's
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- not much I can do, but
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- not much they can do, either.
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The server [rejects remote
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origins](https://git.kittencollective.com/nebkor/hitman/src/commit/1617eae17448273114ca1b1d9277b3465986e9f1/src/main.rs#L45-L48),
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but the `Origin` headers can be trivially forged. On the other hand, the worst someone could do is
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add a bunch of junk to my DB, and I don't care about the data that much; this is all just for
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funsies, anyway!
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## The front end
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I mentioned that this blog is made using Zola, a static site generator. Zola has a built-in
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templating system, so the [following
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bit](https://git.kittencollective.com/nebkor/blog/commit/87afa418b239419f551459e9cc5e838f9fac7ed6)
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of HTML with inlined JavaScript is enough to register a hit and return the latest count:
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``` html
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<div class=hias-footer>
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<p>There have been <span id="hitman-count">no</span> views of this page.</p>
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</div>
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<script defer>
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const hits = document.getElementById('hitman-count');
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fetch("/hit/{{ page.slug }}").then((resp) => {
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if (resp.ok) {
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return resp.text();
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} else {
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return "I don't even know how many";
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}
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}).then((data) => {
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hits.innerHTML = data;
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});
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</script>
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```
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## Putting it all together
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OK, all the pieces are laid out, but here's the actual setup on the backend:
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### Caddy
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The Caddy configuration has the following:
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```
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proclamations.nebcorp-hias.com {
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handle /hit/* {
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reverse_proxy localhost:5000
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}
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handle {
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<all the other routes on the site>
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}
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}
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```
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This means that requests to, eg, `https://proclamations.nebcorp-hias.com/hit/hitman` will register a
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hit for this post, and return the number of views so far.
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### systemd
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I created a system user for the service, `hitman`, with a homedir in `/var/lib/hitman`, and added
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the following systemd unit file into `/etc/systemd/system/hitman.service`:
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```
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Description=Hitman
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After=network.target network-online.target
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Requires=network-online.target
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[Service]
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Type=exec
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User=hitman
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Group=hitman
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ExecStart=/var/lib/hitman/hitman -e /var/lib/hitman/.env
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TimeoutStopSec=5s
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LimitNOFILE=1048576
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LimitNPROC=512
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PrivateTmp=true
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ProtectSystem=full
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[Install]
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WantedBy=multi-user.target
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```
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This will ensure the hitman service is running after boot, and will be restarted if it crashes:
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```
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$ systemctl status hitman.service
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● hitman.service - Hitman
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Loaded: loaded (/etc/systemd/system/hitman.service; enabled; preset: enabled)
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Active: active (running) since Sun 2024-03-31 12:12:14 PDT; 4h 0min ago
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Main PID: 46338 (hitman)
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Tasks: 2 (limit: 1018)
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Memory: 948.0K
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CPU: 53ms
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CGroup: /system.slice/hitman.service
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└─46338 /var/lib/hitman/hitman -e /var/lib/hitman/.env
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```
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### Hitman
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Inside the `/var/lib/hitman` directory there's a `.env` file with the following content:
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```
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DATABASE_URL=sqlite:///${HOME}/.hitman.db
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DATABASE_FILE=${HOME}/.hitman.db
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LISTENING_ADDR=127.0.0.1
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LISTENING_PORT=5000
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HITMAN_ORIGIN=https://proclamations.nebcorp-hias.com
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```
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# Coda
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When I got this working, a friend said, "Drat, that means I need to follow through on my goal to
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write a little web-ring server." Something like two hours later, she had [a working
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webring](https://erikarow.land/notes/gleam-webring), and indeed, if you look at the bottom of this
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very page, you'll see the webring links; as she says, this Web 1.0 stuff is fun!
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---
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[^web1.0]: I think of the hitcounter era as the 90s, but that's because I'm older than the person
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who asked the question.
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[^logs]: They don't mention scrubbing IPs from their logs, but they do mention having logs, so clearly
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the job to scrub the hit DB of hashes is just privacy kabuki.
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