Alexander
2347a02fcb
Add tile-proxy/: a small Rust (axum) service behind nginx that serves one
canonical XYZ scheme (/{karte,luftbild,dufour}/{z}/{x}/{y}) and, per tile,
picks the provider by geometry — swisstopo when the tile overlaps a
swisstopo-covered region (Switzerland or Liechtenstein, each simplified +
2 km buffer; tile-bbox ∩ polygon at every zoom), otherwise OpenTopoMap
(schematic) / Esri World Imagery (satellite), with an auto-fallback for
border 404s. Includes the region generator (gen-regions.mjs), a Makefile,
nginx caching-proxy + systemd examples, and a README. Listen address is
env-driven (TILE_PROXY_ADDR).
App side:
- New mapTiles.ts is the single source for the proxy URLs + combined
attribution; HikeMap / HikesOverviewMap / EditMap fetch through
maps.bocken.org instead of swisstopo directly, on-map attribution
controls removed, preconnect + footer credits updated (swisstopo /
OpenStreetMap+OpenTopoMap / Esri).
- Region-aware schematic max zoom (isSwissRegion helper): detail map caps
at z17 abroad and hides the CH/LI-only Dufour layer; overview caps at
z18 when a shown hike is abroad.
- Route-builder: add the satellite layer via the same bottom-right layer
popover as the other maps.
97 lines
4.1 KiB
Markdown
97 lines
4.1 KiB
Markdown
# tile-proxy
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A tiny region-switching map-tile service for the hikes maps. It exposes one
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canonical XYZ scheme and, **per tile**, serves **swisstopo inside Switzerland
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& Liechtenstein** and a **global provider elsewhere** — so a hike anywhere in
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the world gets a good schematic + satellite basemap, while CH/LI hikes keep
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swisstopo quality.
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```
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browser / build script
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│ https://maps.bocken.org/{layer}/{z}/{x}/{y}
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▼
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nginx ── TLS termination + on-disk tile cache (proxy_cache)
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▼ http://$TILE_PROXY_ADDR (default 127.0.0.1:8765)
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tile-proxy (this crate) ── z/x/y → point-in-polygon → pick + fetch upstream
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▼
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swisstopo │ OpenTopoMap │ Esri World Imagery
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```
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The listen address is set entirely by the **`TILE_PROXY_ADDR`** env var
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(`host:port`); pick whatever port you like. nginx, the systemd unit and this
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binary all reference that one value.
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Caching/TLS/rate-limiting live in **nginx** (Arch's stock nginx has no njs, and
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we want a real geometry test anyway). This binary only does routing + fetch and
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is stateless.
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## Layers & providers
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| `{layer}` | swisstopo region (CH + LI) | elsewhere |
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|------------|----------------------------------|-----------------------|
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| `karte` | `ch.swisstopo.pixelkarte-farbe` | OpenTopoMap |
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| `luftbild` | `ch.swisstopo.swissimage` | Esri World Imagery |
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| `dufour` | `ch.swisstopo.hiks-dufour` | — (CH/LI-only) |
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The swisstopo region is **Switzerland + Liechtenstein** (swisstopo has
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high-quality data for both). A tile is served by swisstopo when it **overlaps**
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that region at all — the tile's lat/lng rectangle is intersected against the
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polygons (`src/regions.in`, simplified + a **2 km outward buffer**), so *any*
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tile touching CH/LI gets swisstopo, at every zoom. (A swisstopo tile partly
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outside its data just renders white at the edges, which beats a foreign
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provider drawing over covered ground.) For `karte`/`luftbild`, a swisstopo tile
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that 404s near the edge falls back to the global provider automatically.
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## Build & run
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```sh
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cargo build --release
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TILE_PROXY_ADDR=127.0.0.1:8765 ./target/release/tile-proxy
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# smoke test
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curl -s -o /dev/null -w '%{http_code} %{content_type}\n' \
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http://127.0.0.1:8765/karte/9/266/180 # Bern → swisstopo (jpeg)
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curl -s -o /dev/null -w '%{http_code} %{content_type}\n' \
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http://127.0.0.1:8765/karte/9/255/171 # London → OpenTopoMap (png)
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```
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`TILE_PROXY_ADDR` defaults to `127.0.0.1:8765` but should be set explicitly.
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`GET /healthz` returns `ok`.
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Run it as a service with [`deploy/tile-proxy.service`](deploy/tile-proxy.service)
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and put nginx in front with [`deploy/nginx.conf.example`](deploy/nginx.conf.example).
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## Regenerating the region polygons
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`src/regions.in` is generated — don't hand-edit it. To refresh (or change the
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buffer / simplification, or add a region):
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```sh
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make regions # CH + LI, default 2 km buffer
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BUFFER_KM=2 SIMPLIFY_DEG=0.004 node scripts/gen-regions.mjs
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node scripts/gen-regions.mjs ./ch.geojson ./li.geojson # local files
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```
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It takes each source's largest exterior ring, Douglas–Peucker–simplifies it,
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then pushes every vertex outward by `BUFFER_KM`. Rebuild the binary afterwards
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(the ring is baked in via `include!`). If you move the boundary, purge the nginx
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cache so old tiles aren't served by the previous provider.
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## Attribution (required)
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All three providers require credit — keep these on the page (the hikes pages
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show them in the footer):
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- **© swisstopo** — Swiss tiles.
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- **© OpenStreetMap contributors, SRTM | © OpenTopoMap (CC-BY-SA)** — world schematic.
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- **© Esri, Maxar, Earthstar Geographics** — world satellite.
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## Notes
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- **Max zoom** differs by provider — clamp the client: OpenTopoMap 17,
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Esri imagery ~19, swisstopo 19/20.
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- **OpenTopoMap fair-use:** it's a small volunteer project; the long nginx
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cache + a descriptive `User-Agent` is the mitigation. If traffic grows,
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self-host a renderer.
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- **Dufour** has no world equivalent — the client hides that layer when the
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view leaves Switzerland.
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