Tile server migration

application/factory.py

@@ -31,6 +31,7 @@
     fact,
     guidance_,
     about_,
+    tiles_,
     osMapOAuth,
 )
 from application.settings import get_settings
@@ -269,6 +270,7 @@ def add_routers(app):
     app.include_router(map_.router, prefix="/map", include_in_schema=False)
     app.include_router(guidance_.router, prefix="/guidance", include_in_schema=False)
     app.include_router(about_.router, prefix="/about", include_in_schema=False)
+    app.include_router(tiles_.router, prefix="/tiles", include_in_schema=False)
 
 
 def add_static(app):
@@ -291,9 +293,9 @@ def add_middleware(app):
     @app.middleware("http")
     async def add_strict_transport_security_header(request: Request, call_next):
         response = await call_next(request)
-        response.headers[
-            "Strict-Transport-Security"
-        ] = f"max-age={SECONDS_IN_TWO_YEARS}; includeSubDomains; preload"
+        response.headers["Strict-Transport-Security"] = (
+            f"max-age={SECONDS_IN_TWO_YEARS}; includeSubDomains; preload"
+        )
         return response
 
     @app.middleware("http")

application/routers/tiles_.py

@@ -0,0 +1,161 @@
+import logging
+
+from fastapi import APIRouter, HTTPException
+from fastapi.responses import StreamingResponse
+
+import psycopg2
+from io import BytesIO
+
+from application.settings import get_settings
+
+router = APIRouter()
+logger = logging.getLogger(__name__)
+
+DATABASE = {"user": "", "password": "", "host": "", "port": "5432", "database": ""}
+
+DATABASE_CONNECTION = None
+
+QUERY_PARAMS = {
+    "table1": "entity t1",
+    "srid": "4326",
+    "geomColumn": "t1.geometry",
+    "attrColumns": "t1.entity, t1.name, t1.reference",
+}
+
+
+# ============================================================
+# Helper Funcs
+# ============================================================
+def get_db_connection():
+    conn_str = get_settings()
+
+    DATABASE["user"] = conn_str.READ_DATABASE_URL.user
+    DATABASE["password"] = conn_str.READ_DATABASE_URL.password
+    DATABASE["host"] = conn_str.READ_DATABASE_URL.host
+    DATABASE["database"] = conn_str.READ_DATABASE_URL.path.split("/")[1]
+
+
+get_db_connection()
+
+
+# Do the tile x/y coordinates make sense at this zoom level?
+def tile_is_valid(tile):
+    if not ("x" in tile and "y" in tile and "zoom" in tile):
+        return False
+
+    if "format" not in tile or tile["format"] not in ["pbf", "mvt"]:
+        return False
+
+    size = 2 ** tile["zoom"]
+
+    if tile["x"] >= size or tile["y"] >= size:
+        return False
+
+    if tile["x"] < 0 or tile["y"] < 0:
+        return False
+
+    return True
+
+
+def build_db_query(tile):
+    qry_params = QUERY_PARAMS.copy()
+    qry_params["dataset"] = tile["dataset"]
+    qry_params["x"] = tile["x"]
+    qry_params["y"] = tile["y"]
+    qry_params["z"] = tile["zoom"]
+
+    query = """
+    WITH
+    webmercator(envelope) AS (
+        SELECT ST_TileEnvelope({z}, {x}, {y})
+    ),
+    wgs84(envelope) AS (
+      SELECT ST_Transform((SELECT envelope FROM webmercator), {srid})
+    ),
+    b(bounds) AS (
+      SELECT ST_MakeEnvelope(-180, -85.0511287798066, 180, 85.0511287798066, {srid})
+    ),
+    geometries(entity, name, reference, wkb_geometry) AS (
+        SELECT
+            {attrColumns},
+            CASE WHEN ST_Covers(b.bounds, {geomColumn})
+                 THEN ST_Transform({geomColumn},{srid})
+                 ELSE ST_Transform(ST_Intersection(b.bounds, {geomColumn}),{srid})
+            END
+        FROM
+            {table1}
+        CROSS JOIN
+            b
+        WHERE
+            {geomColumn} && (SELECT envelope FROM wgs84)
+          AND
+            t1.dataset = '{dataset}'
+    )
+    SELECT
+        ST_AsMVT(tile, '{dataset}') as mvt
+    FROM (
+      SELECT
+        entity,
+        name,
+        reference,
+        ST_AsMVTGeom(wkb_geometry, (SELECT envelope FROM wgs84))
+      FROM geometries
+    ) AS tile
+    """.format(
+        **qry_params
+    )
+
+    return query
+
+
+def sql_to_pbf(sql):
+    global DATABASE_CONNECTION
+
+    # Make and hold connection to database
+    if not DATABASE_CONNECTION:
+        try:
+            DATABASE_CONNECTION = psycopg2.connect(**DATABASE)
+        except (Exception, psycopg2.Error) as error:
+            logger.warning(error)
+            return None
+
+    # Query for MVT
+    with DATABASE_CONNECTION.cursor() as cur:
+        cur.execute(sql)
+        if not cur:
+            logger.warning(f"sql query failed: {sql}")
+            return None
+
+        return cur.fetchone()[0]
+
+    return None
+
+
+# ============================================================
+# API Endpoints
+# ============================================================
+
+
+@router.get("/-/tiles/{dataset}/{z}/{x}/{y}.vector.{fmt}")
+async def read_tiles_from_postgres(dataset: str, z: int, x: int, y: int, fmt: str):
+    tile = {"dataset": dataset, "zoom": z, "x": x, "y": y, "format": fmt}
+
+    if not tile_is_valid(tile):
+        raise HTTPException(status_code=400, detail=f"invalid tile path: {tile}")
+
+    sql = build_db_query(tile)
+
+    pbf = sql_to_pbf(sql)
+
+    pbf_buffer = BytesIO()
+    pbf_buffer.write(pbf)
+    pbf_buffer.seek(0)
+
+    resp_headers = {
+        "Access-Control-Allow-Origin": "*",
+        "Content-Type": "application/vnd.mapbox-vector-tile",
+    }
+
+    return StreamingResponse(
+        pbf_buffer, media_type="vnd.mapbox-vector-tile", headers=resp_headers
+    )