Watermarks

Enable Workers Cache so repeat requests for the same watermarked image are served from cache without re-running the Worker or re-transforming the image:

{
	"cache": {
		"enabled": true,
	},
}

[cache]
enabled = true

Then set Cache-Control headers on your response to control the cache lifetime:

export default {
	async fetch(request, env) {
		const watermarkKey = "my-watermark";
		const sourceKey = "my-source-image";

		const watermark = await env.NAMESPACE.get(watermarkKey, "stream");
		const source = await env.BUCKET.get(sourceKey);

		if (!watermark || !source) {
			return new Response("Not found", { status: 404 });
		}

		const result = await env.IMAGES.input(source.body)
			.draw(watermark)
			.output({ format: "image/jpeg" });

		const response = result.response();

		return new Response(response.body, {
			headers: {
				...Object.fromEntries(response.headers),
				"Cache-Control": "public, max-age=3600, stale-while-revalidate=86400",
			},
		});
	},
};

interface Env {
	BUCKET: R2Bucket;
	NAMESPACE: KVNamespace;
	IMAGES: ImagesBinding;
}
export default {
	async fetch(request, env): Promise<Response> {
		const watermarkKey = "my-watermark";
		const sourceKey = "my-source-image";

		const watermark = await env.NAMESPACE.get(watermarkKey, "stream");
		const source = await env.BUCKET.get(sourceKey);

		if (!watermark || !source) {
			return new Response("Not found", { status: 404 });
		}

		const result = await env.IMAGES.input(source.body)
			.draw(watermark)
			.output({ format: "image/jpeg" });

		const response = result.response();

		return new Response(response.body, {
			headers: {
				...Object.fromEntries(response.headers),
				"Cache-Control": "public, max-age=3600, stale-while-revalidate=86400",
			},
		});
	},
} satisfies ExportedHandler<Env>;