Custom limits allow you to programmatically enforce limits on your customers' Workers' resource usage. You can set limits for the maximum CPU time and number of subrequests per invocation. If a user Worker hits either of these limits, the user Worker will immediately throw an exception.
Custom limits can be set in the dynamic dispatch Worker:
export default {
async fetch(request, env) {
try {
// parse the URL, read the subdomain
let workerName = new URL(request.url).host.split(".")[0];
let userWorker = env.dispatcher.get(
workerName,
{},
{
// set limits
limits: { cpuMs: 10, subRequests: 5 },
},
);
return await userWorker.fetch(request);
} catch (e) {
if (e.message.startsWith("Worker not found")) {
// we tried to get a worker that doesn't exist in our dispatch namespace
return new Response("", { status: 404 });
}
return new Response(e.message, { status: 500 });
}
},
};