From 9fa252a6aff033e33a841d9069416d3892b6918c Mon Sep 17 00:00:00 2001
From: Shautvast <shautvast@gmail.com>
Date: Tue, 31 Mar 2026 21:53:52 +0200
Subject: [PATCH] seed tiles

---
 backend/docker-compose.yml    |  14 ++++
 backend/scripts/seed_tiles.py | 122 ++++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)
 create mode 100644 backend/scripts/seed_tiles.py

diff --git a/backend/docker-compose.yml b/backend/docker-compose.yml
index c75d332..ae1bb59 100644
--- a/backend/docker-compose.yml
+++ b/backend/docker-compose.yml
@@ -31,6 +31,20 @@ services:
       - osrm-walking
       - osrm-cycling
 
+  tile-seeder:
+    image: python:3-slim
+    networks:
+      - maps-net
+    volumes:
+      - ./scripts:/scripts:ro
+    environment:
+      BACKEND_URL: "http://backend:8080"
+      SEED_WORKERS: "4"
+    command: python3 /scripts/seed_tiles.py
+    restart: "no"
+    depends_on:
+      - backend
+
   postgres:
     build:
       context: .
diff --git a/backend/scripts/seed_tiles.py b/backend/scripts/seed_tiles.py
new file mode 100644
index 0000000..2cfa2be
--- /dev/null
+++ b/backend/scripts/seed_tiles.py
@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+"""
+Pre-warm the Redis tile cache by fetching all tiles for a bounding box.
+
+Tiles are fetched through the backend, which caches them in Redis automatically.
+Run this in the background after starting the stack:
+
+  nohup python3 scripts/seed_tiles.py &
+
+Usage:
+  python3 seed_tiles.py [min_lon] [min_lat] [max_lon] [max_lat] [min_zoom] [max_zoom]
+
+Defaults to the Netherlands at zoom levels 0-12.
+"""
+
+import math
+import sys
+import time
+import urllib.request
+import urllib.error
+from concurrent.futures import ThreadPoolExecutor, as_completed
+
+import os
+
+BACKEND_URL = os.environ.get("BACKEND_URL", "http://localhost:8080")
+LAYERS = ["planet_osm_polygon", "planet_osm_line", "planet_osm_point", "planet_osm_roads"]
+WORKERS = int(os.environ.get("SEED_WORKERS", "4"))
+
+
+def wait_for_backend():
+    """Wait until the backend health endpoint responds."""
+    url = f"{BACKEND_URL}/health"
+    print(f"Waiting for backend at {url}...")
+    while True:
+        try:
+            with urllib.request.urlopen(url, timeout=5) as resp:
+                if resp.status == 200:
+                    print("Backend is up.")
+                    return
+        except Exception:
+            pass
+        time.sleep(3)
+
+
+def lon_to_x(lon, zoom):
+    return int((lon + 180.0) / 360.0 * (1 << zoom))
+
+
+def lat_to_y(lat, zoom):
+    lat_r = math.radians(lat)
+    return int((1.0 - math.log(math.tan(lat_r) + 1.0 / math.cos(lat_r)) / math.pi) / 2.0 * (1 << zoom))
+
+
+def tiles_for_bbox(min_lon, min_lat, max_lon, max_lat, zoom):
+    max_coord = (1 << zoom) - 1
+    x_min = max(0, min(lon_to_x(min_lon, zoom), max_coord))
+    x_max = max(0, min(lon_to_x(max_lon, zoom), max_coord))
+    y_min = max(0, min(lat_to_y(max_lat, zoom), max_coord))  # max_lat → smaller y
+    y_max = max(0, min(lat_to_y(min_lat, zoom), max_coord))  # min_lat → larger y
+    for x in range(x_min, x_max + 1):
+        for y in range(y_min, y_max + 1):
+            yield zoom, x, y
+
+
+def fetch_tile(layer, z, x, y):
+    url = f"{BACKEND_URL}/tiles/{layer}/{z}/{x}/{y}.pbf"
+    try:
+        with urllib.request.urlopen(url, timeout=120) as resp:
+            return resp.status == 200
+    except urllib.error.HTTPError:
+        return False
+    except Exception:
+        return False
+
+
+def main():
+    wait_for_backend()
+
+    min_lon  = float(sys.argv[1]) if len(sys.argv) > 1 else 3.3
+    min_lat  = float(sys.argv[2]) if len(sys.argv) > 2 else 50.7
+    max_lon  = float(sys.argv[3]) if len(sys.argv) > 3 else 7.2
+    max_lat  = float(sys.argv[4]) if len(sys.argv) > 4 else 53.6
+    min_zoom = int(sys.argv[5])   if len(sys.argv) > 5 else 0
+    max_zoom = int(sys.argv[6])   if len(sys.argv) > 6 else 12
+
+    # Build full task list
+    tasks = []
+    for zoom in range(min_zoom, max_zoom + 1):
+        coords = list(tiles_for_bbox(min_lon, min_lat, max_lon, max_lat, zoom))
+        tile_count = len(coords)
+        print(f"  z{zoom}: {tile_count} tiles × {len(LAYERS)} layers = {tile_count * len(LAYERS)} requests")
+        for z, x, y in coords:
+            for layer in LAYERS:
+                tasks.append((layer, z, x, y))
+
+    total = len(tasks)
+    print(f"\nTotal: {total} requests — starting with {WORKERS} workers...\n")
+
+    done = 0
+    errors = 0
+    start = time.time()
+
+    with ThreadPoolExecutor(max_workers=WORKERS) as executor:
+        futures = {executor.submit(fetch_tile, *t): t for t in tasks}
+        for future in as_completed(futures):
+            ok = future.result()
+            done += 1
+            if not ok:
+                errors += 1
+            if done % 50 == 0 or done == total:
+                elapsed = time.time() - start
+                rate = done / elapsed if elapsed > 0 else 0
+                eta = (total - done) / rate if rate > 0 else 0
+                pct = 100 * done // total
+                print(f"  {done}/{total} ({pct}%) | {errors} errors | {rate:.1f} req/s | ETA {eta:.0f}s")
+
+    elapsed = time.time() - start
+    print(f"\nDone: {total - errors}/{total} tiles seeded in {elapsed:.0f}s")
+
+
+if __name__ == "__main__":
+    main()