Revert "feat(lambda-tiler): return 204 no content instead of a empty images (#2829)" (#2836)

This reverts commit db3ff1b.

Research documentation suggest to use 200 Transparent Image.
https://github.com/linz/basemaps/blob/master/docs/api/empty-tiles.md

Author: Wentao-Kuang

packages/lambda-tiler/src/__tests__/config.data.ts

@@ -20,7 +20,6 @@ export const TileSetAerial: ConfigTileSetRaster = {
   description: 'aerial__description',
   title: 'Aerial Imagery',
   category: 'Basemap',
-  background: { r: 0xff, g: 0x00, b: 0xff, alpha: 0.5 },
   layers: [
     {
       2193: 'im_01FYWKAJ86W9P7RWM1VB62KD0H',

packages/lambda-tiler/src/routes/__tests__/attribution.test.ts

@@ -309,12 +309,12 @@ o.spec('/v1/attribution', () => {
 
   o('should 304 with etag match', async () => {
     const request = mockUrlRequest(`/v1/attribution/aerial/EPSG:3857/summary.json`, 'get', {
-      [HttpHeader.IfNoneMatch]: '3un15yA8o1ZDiyYpHXwUQHYXPxd5uGtzHS3R8gug9Nn1',
+      [HttpHeader.IfNoneMatch]: 'E5HGpTqF8AiJ7VgGVKLehYnVfLN9jaVw8Sy6UafJRh2f',
     });
 
     const res = await handler.router.handle(request);
 
-    if (res.status === 200) o(res.header('etag')).equals('3un15yA8o1ZDiyYpHXwUQHYXPxd5uGtzHS3R8gug9Nn1');
+    if (res.status === 200) o(res.header('etag')).equals('E5HGpTqF8AiJ7VgGVKLehYnVfLN9jaVw8Sy6UafJRh2f');
 
     console.log(res.header('etag'));
     o(res.status).equals(304);

packages/lambda-tiler/src/routes/__tests__/xyz.test.ts

@@ -100,16 +100,6 @@ o.spec('/v1/tiles', () => {
     o(resB.status).equals(404);
   });
 
-  o('should 204 if a tile is outside of the bounds', async () => {
-    const fakeTileSet = FakeData.tileSetRaster('🦄 🌈');
-    fakeTileSet.background = undefined;
-    config.put(fakeTileSet);
-    const res = await handler.router.handle(
-      mockRequest('/v1/tiles/🦄 🌈/global-mercator/0/0/0.png', 'get', Api.header),
-    );
-    o(res.status).equals(204);
-  });
-
   o('should support utf8 tilesets', async () => {
     const fakeTileSet = FakeData.tileSetRaster('🦄 🌈');
     config.put(fakeTileSet);

packages/lambda-tiler/src/routes/tile.xyz.raster.ts

@@ -10,7 +10,7 @@ import pLimit from 'p-limit';
 import { ConfigLoader } from '../util/config.loader.js';
 import { Etag } from '../util/etag.js';
 import { filterLayers } from '../util/filter.js';
-import { NoContent, NotFound, NotModified } from '../util/response.js';
+import { NotFound, NotModified } from '../util/response.js';
 import { CoSources } from '../util/source.cache.js';
 import { TileXyz } from '../util/validate.js';
 
@@ -106,25 +106,14 @@ export const TileXyzRaster = {
     const tiler = new Tiler(xyz.tileMatrix);
     const layers = await tiler.tile(assets, xyz.tile.x, xyz.tile.y, xyz.tile.z);
 
-    const background = tileSet.background ?? DefaultBackground;
-
     const res = await TileComposer.compose({
       layers,
       format: xyz.tileType,
-      background,
+      background: tileSet.background ?? DefaultBackground,
       resizeKernel: tileSet.resizeKernel ?? DefaultResizeKernel,
       metrics: req.timer,
     });
 
-    // If no layers are used and the tile is going to be transparent
-    // return 204 no content instead of a empty image
-    if (res.layers === 0 && background.alpha === 0) {
-      const response = NoContent();
-      response.header(HttpHeader.ETag, cacheKey);
-      response.header(HttpHeader.CacheControl, 'public, max-age=604800, stale-while-revalidate=86400');
-      return response;
-    }
-
     req.set('layersUsed', res.layers);
     req.set('bytes', res.buffer.byteLength);