valhalla_modal_example.py

import json
import subprocess
import sys
import tempfile

import modal

stub = modal.Stub()
stub.sv = modal.SharedVolume().persist("valhalla")
image = modal.DockerhubImage("valhalla/valhalla:run-latest", setup_commands=["apt-get update", "apt-get install -y python3-pip"])

def run_command(cmd):
    subprocess.run(cmd, shell=True, stdout=sys.stdout, stderr=sys.stderr)


@stub.function(image=image, shared_volumes={"/valhalla": stub.sv})
def install():
    run_command("wget -P /valhalla http://download.geofabrik.de/europe/liechtenstein-latest.osm.pbf")
    run_command("mkdir -p /valhalla/tiles")
    run_command("valhalla_build_config --mjolnir-tile-dir /valhalla/tiles --mjolnir-tile-extract /valhalla/tiles.tar --mjolnir-timezone /valhalla/tiles/timezones.sqlite --mjolnir-admin /valhalla/tiles/admins.sqlite > /valhalla/valhalla.json")
    run_command("valhalla_build_timezones > /valhalla/tiles/timezones.sqlite")
    run_command("valhalla_build_tiles -c /valhalla/valhalla.json /valhalla/liechtenstein-latest.osm.pbf")
    run_command("valhalla_build_extract -c /valhalla/valhalla.json -v")


@stub.function(image=image, shared_volumes={"/valhalla": stub.sv})
def isochrone(payload):
    with tempfile.NamedTemporaryFile() as t:
        with open(t.name, "w") as f:
            json.dump(payload, f)
        p = subprocess.run(f"valhalla_service /valhalla/valhalla.json isochrone {t.name}", shell=True, capture_output=True)
        return json.loads(p.stdout)


if __name__ == "__main__":
    with stub.run():
        # uncomment this if you want to install everything (slow)
        # install()
        payload = {
            "locations": [
                {"lat": 47.1410, "lon": 9.5209},  # vaduz
            ],
            "costing":"pedestrian",
            "contours": [
                {"time": 10, "color": "ff0000"}
            ],
            "show_locations": True
        }

        # Compute a single isochrone
        result = isochrone(payload)
        print(result)

        # Use Modal to parallelize and compute 1000 isochrones
        results = []
        for result in isochrone.map([payload] * 1000):
            results.append(result)
            print(f"got {len(results)} results so far")