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Router worker performs free tier limiting #9360

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Router worker performs free tier limiting #9360

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4ef1858
WC-3584 Refactor routing to asset or user worker
matthewdavidrodgers May 23, 2025
0da20d4
WC-3584 Add eyeball routing config
matthewdavidrodgers May 23, 2025
6405344
WC-3584 Deny requests to the user worker when over free tier limits
matthewdavidrodgers May 23, 2025
7ceb1f2
WC-3584 Add changeset
matthewdavidrodgers May 23, 2025
a1cd3f8
WC-3584 Move the limited response page to be inlined
matthewdavidrodgers Jun 13, 2025
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5 changes: 5 additions & 0 deletions .changeset/tidy-bobcats-lose.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"@cloudflare/workers-shared": minor
---

Limit free tier requests in the Router worker
3 changes: 3 additions & 0 deletions packages/workers-shared/router-worker/src/analytics.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,8 @@ type Data = {
userWorkerAhead?: boolean;
// double6 - Routing performed based on the _routes.json (if provided)
staticRoutingDecision?: STATIC_ROUTING_DECISION;
// double7 - User worker invocation denied due to free tier limiting
userWorkerFreeTierLimiting?: boolean;

// -- Blobs --
// blob1 - Hostname of the request
Expand Down Expand Up @@ -88,6 +90,7 @@ export class Analytics {
? -1
: Number(this.data.userWorkerAhead),
this.data.staticRoutingDecision ?? STATIC_ROUTING_DECISION.NOT_PROVIDED, // double6
this.data.userWorkerFreeTierLimiting ? 1 : 0, // double7
],
blobs: [
this.data.hostname?.substring(0, 256), // blob1 - trim to 256 bytes
Expand Down
14 changes: 12 additions & 2 deletions packages/workers-shared/router-worker/src/configuration.ts
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
import type { RouterConfig } from "../../utils/types";
import type { EyeballRouterConfig, RouterConfig } from "../../utils/types";

export const applyConfigurationDefaults = (
type RequiredEyeballRouterConfig = Required<Exclude<EyeballRouterConfig, null>>;

export const applyRouterConfigDefaults = (
configuration?: RouterConfig
): Required<RouterConfig> => {
return {
Expand All @@ -15,3 +17,11 @@ export const applyConfigurationDefaults = (
},
};
};

export const applyEyeballConfigDefaults = (
eyeballConfiguration?: EyeballRouterConfig
): RequiredEyeballRouterConfig => {
return {
limitedAssetsOnly: eyeballConfiguration?.limitedAssetsOnly ?? false,
};
};
145 changes: 83 additions & 62 deletions packages/workers-shared/router-worker/src/worker.ts
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Expand Up @@ -3,19 +3,46 @@ import { PerformanceTimer } from "../../utils/performance";
import { setupSentry } from "../../utils/sentry";
import { mockJaegerBinding } from "../../utils/tracing";
import { Analytics, DISPATCH_TYPE, STATIC_ROUTING_DECISION } from "./analytics";
import { applyConfigurationDefaults } from "./configuration";
import {
applyEyeballConfigDefaults,
applyRouterConfigDefaults,
} from "./configuration";
import type AssetWorker from "../../asset-worker";
import type {
EyeballRouterConfig,
JaegerTracing,
RouterConfig,
UnsafePerformanceTimer,
} from "../../utils/types";
import type { ColoMetadata, Environment, ReadyAnalytics } from "./types";

const limitedResponse = `<html>
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@GregBrimble GregBrimble Jun 18, 2025

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styling and wording approved now? It's a bit of a departure from our usual styling.

<head>
<title>This website is temporarily limited</title>
</head>
<body>
<h1>This website has been temporarily rate limited</h1>
<p>
You cannot access this site because the owner has reached their plan
limits. Check back later once traffic has gone down.
</p>
<p>
If you are owner of this website, prevent this from happening again by
upgrading your plan on the
<a
href="https://dash.cloudflare.com/?account=workers/plans"
target="_blank"
>Cloudflare Workers dashboard</a
>.
</p>
</body>
</html>`;

export interface Env {
ASSET_WORKER: Service<AssetWorker>;
USER_WORKER: Fetcher;
CONFIG: RouterConfig;
EYEBALL_CONFIG: EyeballRouterConfig;

SENTRY_DSN: string;
ENVIRONMENT: Environment;
Expand Down Expand Up @@ -55,7 +82,8 @@ export default {
);

const hasStaticRouting = env.CONFIG.static_routing !== undefined;
const config = applyConfigurationDefaults(env.CONFIG);
const config = applyRouterConfigDefaults(env.CONFIG);
const eyeballConfig = applyEyeballConfigDefaults(env.EYEBALL_CONFIG);

const url = new URL(request.url);

Expand All @@ -77,6 +105,54 @@ export default {

const maybeSecondRequest = request.clone();

const routeToUserWorker = async ({
asset,
}: {
asset: "static_routing" | "none";
}) => {
if (!config.has_user_worker) {
throw new Error(
"Fetch for user worker without having a user worker binding"
);
}
if (eyeballConfig.limitedAssetsOnly) {
analytics.setData({ userWorkerFreeTierLimiting: true });
return new Response(limitedResponse, {
status: 429,
headers: {
"Content-Type": "text/html",
},
});
}
analytics.setData({ dispatchtype: DISPATCH_TYPE.WORKER });
userWorkerInvocation = true;
return env.JAEGER.enterSpan("dispatch_worker", async (span) => {
span.setTags({
hasUserWorker: true,
asset: asset,
dispatchType: DISPATCH_TYPE.WORKER,
});
return env.USER_WORKER.fetch(maybeSecondRequest);
});
};

const routeToAssets = async ({
asset,
}: {
asset: "static_routing" | "found" | "none";
}) => {
analytics.setData({ dispatchtype: DISPATCH_TYPE.ASSETS });
return await env.JAEGER.enterSpan("dispatch_assets", async (span) => {
span.setTags({
hasUserWorker: config.has_user_worker,
asset: asset,
dispatchType: DISPATCH_TYPE.ASSETS,
});

return env.ASSET_WORKER.fetch(maybeSecondRequest);
});
};

if (config.static_routing) {
// evaluate "exclude" rules
const excludeRulesMatcher = generateStaticRoutingRuleMatcher(
Expand All @@ -89,18 +165,9 @@ export default {
) {
// direct to asset worker
analytics.setData({
dispatchtype: DISPATCH_TYPE.ASSETS,
staticRoutingDecision: STATIC_ROUTING_DECISION.ROUTED,
});
return await env.JAEGER.enterSpan("dispatch_assets", async (span) => {
span.setTags({
hasUserWorker: config.has_user_worker,
asset: "static_routing",
dispatchType: DISPATCH_TYPE.ASSETS,
});

return env.ASSET_WORKER.fetch(maybeSecondRequest);
});
return await routeToAssets({ asset: "static_routing" });
}
// evaluate "include" rules
const includeRulesMatcher = generateStaticRoutingRuleMatcher(
Expand All @@ -118,19 +185,9 @@ export default {
}
// direct to user worker
analytics.setData({
dispatchtype: DISPATCH_TYPE.WORKER,
staticRoutingDecision: STATIC_ROUTING_DECISION.ROUTED,
});
return await env.JAEGER.enterSpan("dispatch_worker", async (span) => {
span.setTags({
hasUserWorker: true,
asset: "static_routing",
dispatchType: DISPATCH_TYPE.WORKER,
});

userWorkerInvocation = true;
return env.USER_WORKER.fetch(maybeSecondRequest);
});
return await routeToUserWorker({ asset: "static_routing" });
}

analytics.setData({
Expand All @@ -143,53 +200,17 @@ export default {
// User's configuration indicates they want user-Worker to run ahead of any
// assets. Do not provide any fallback logic.
if (config.invoke_user_worker_ahead_of_assets) {
if (!config.has_user_worker) {
throw new Error(
"Fetch for user worker without having a user worker binding"
);
}

analytics.setData({ dispatchtype: DISPATCH_TYPE.WORKER });
return await env.JAEGER.enterSpan("dispatch_worker", async (span) => {
span.setTags({
hasUserWorker: true,
asset: "ignored",
dispatchType: DISPATCH_TYPE.WORKER,
});

userWorkerInvocation = true;
return env.USER_WORKER.fetch(maybeSecondRequest);
});
return await routeToUserWorker({ asset: "static_routing" });
}

// If we have a user-Worker, but no assets, dispatch to Worker script
const assetsExist = await env.ASSET_WORKER.unstable_canFetch(request);
if (config.has_user_worker && !assetsExist) {
analytics.setData({ dispatchtype: DISPATCH_TYPE.WORKER });

return await env.JAEGER.enterSpan("dispatch_worker", async (span) => {
span.setTags({
hasUserWorker: config.has_user_worker,
asset: assetsExist,
dispatchType: DISPATCH_TYPE.WORKER,
});

userWorkerInvocation = true;
return env.USER_WORKER.fetch(maybeSecondRequest);
});
return await routeToUserWorker({ asset: "none" });
}

// Otherwise, we either don't have a user worker, OR we have matching assets and should fetch from the assets binding
analytics.setData({ dispatchtype: DISPATCH_TYPE.ASSETS });
return await env.JAEGER.enterSpan("dispatch_assets", async (span) => {
span.setTags({
hasUserWorker: config.has_user_worker,
asset: assetsExist,
dispatchType: DISPATCH_TYPE.ASSETS,
});

return env.ASSET_WORKER.fetch(maybeSecondRequest);
});
return await routeToAssets({ asset: assetsExist ? "found" : "none" });
} catch (err) {
if (userWorkerInvocation) {
// Don't send user Worker errors to sentry; we have no way to distinguish between
Expand Down
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