github_pulse

A Cloudflare Worker, written in Rust with workers-rs, that serves a live SVG styled like dmesg -T --follow. It shows what you're listening to on Spotify, recent GitHub activity, local weather and daylight, and a career "uptime". It's meant to be embedded in a GitHub profile README:

<img src="https://pulse.example.com/dmesg.svg" alt="Live dmesg feed" width="100%" />

/dmesg.svg always returns 200. If a source fails, its line becomes a yellow WARN line, or its last good value is shown dimmed.

Endpoints

Route	Returns
GET /dmesg.svg	image/svg+xml: the card. Always 200.
GET /health	text/plain: ok.
GET /	text/plain: a description of these endpoints and an embed snippet.

Layout

Crate	What it is
crates/core (pulse-core)	Config, line model, SVG renderer and API parsers. No I/O; tested natively.
crates/worker (pulse-worker)	The Worker: HTTP, KV, Cache API and the cron.
crates/cli (pulse)	Local tooling: config sync, Spotify auth and previews.

Setup

1. Run npm install. This installs a pinned wrangler locally.

2. Run cp config.example.toml config.toml && chmod 600 config.toml, then fill it in. config.toml is gitignored and holds both settings and secrets.

3. Run npx wrangler login, then npx wrangler kv namespace create PULSE. Put the namespace id in worker.kv_namespace_id.

4. Create a Spotify app at developer.spotify.com with the redirect URI http://127.0.0.1:8888/callback. Put its id and secret in [secrets], then run:

   cargo run -p pulse-cli -- auth spotify

5. Create a fine-grained GitHub token (public repositories, read-only) and put it in secrets.github_token.

6. Run cargo run -p pulse-cli -- sync. It generates wrangler.toml and .dev.vars, both gitignored.

Develop

cargo test --workspace
cargo run -p pulse-cli -- render > preview.svg          # preview from fixtures
npx wrangler dev --test-scheduled                       # http://localhost:8787/dmesg.svg
curl "localhost:8787/__scheduled?cron=*/10+*+*+*+*"     # run the cron once

Renderer snapshots use insta. After an intended change, run INSTA_UPDATE=always cargo test -p pulse-core and review the diff.

Deploy

cargo run -p pulse-cli -- sync --push-secrets   # uploads [secrets] via `wrangler secret bulk`
npx wrangler deploy

If worker.domain is set, the Worker is served on that custom domain. The domain's zone must be on your Cloudflare account.

How data flows

Source	Refreshed	Stored
Weather (Open-Meteo, no key)	cron, every 10 min	KV src:weather
GitHub events + recent repos	cron, every 10 min	KV src:github
Spotify now playing / last played	on request	Cache API, 30 s
Uptime	computed per request	none

The cron writes a key only when its content changed, or once an hour so an unchanged value can prove it's still fresh. A value that hasn't refreshed in 90 minutes renders dimmed.

On *.workers.dev, the Cache API is a no-op, so every request fetches Spotify. A custom domain gets the 30-second cache.

KV write budget (free plan: 1,000/day)

Key	Writes/day
src:weather	≤ 96 changes (Open-Meteo updates every 15 min) + ≤ 24 hourly rewrites; at most 144
src:github	changes plus ≤ 24 hourly rewrites; usually ~25, at most 144
spotify:access_token	~24 (one-hour tokens), a few more if isolates race
spotify:refresh_token	only when Spotify rotates it; rare
Total	about 150 typical, about 320 worst case