Use Queues to store data in R2

The following Worker will catch JavaScript errors and send them to a queue. The same Worker will receive those errors in batches and store them to a log file in an R2 bucket.

wrangler.jsonc

{
  "$schema": "./node_modules/wrangler/config-schema.json",
  "name": "my-worker",
  "queues": {
    "producers": [
      {
        "queue": "my-queue",
        "binding": "ERROR_QUEUE"
      }
    ],
    "consumers": [
      {
        "queue": "my-queue",
        "max_batch_size": 100,
        "max_batch_timeout": 30
      }
    ]
  },
  "r2_buckets": [
    {
      "bucket_name": "my-bucket",
      "binding": "ERROR_BUCKET"
    }
  ]
}

wrangler.toml

"$schema" = "./node_modules/wrangler/config-schema.json"
name = "my-worker"

[[queues.producers]]
queue = "my-queue"
binding = "ERROR_QUEUE"

[[queues.consumers]]
queue = "my-queue"
max_batch_size = 100
max_batch_timeout = 30

[[r2_buckets]]
bucket_name = "my-bucket"
binding = "ERROR_BUCKET"

TypeScript

interface ErrorMessage {
  message: string;
  stack?: string;
}

interface Env {
  readonly ERROR_QUEUE: Queue<ErrorMessage>;
  readonly ERROR_BUCKET: R2Bucket;
}

export default {
  async fetch(req, env, ctx): Promise<Response> {
    try {
      return doRequest(req);
    } catch (e) {
      const error: ErrorMessage = {
        message: e instanceof Error ? e.message : String(e),
        stack: e instanceof Error ? e.stack : undefined,
      };
      await env.ERROR_QUEUE.send(error);
      return new Response(error.message, { status: 500 });
    }
  },
  async queue(batch, env, ctx): Promise<void> {
    let file = "";
    for (const message of batch.messages) {
      const error = message.body;
      file += error.stack ?? error.message;
      file += "\r\n";
    }
    await env.ERROR_BUCKET.put(`errors/${Date.now()}.log`, file);
  },
} satisfies ExportedHandler<Env, ErrorMessage>;

function doRequest(request: Request): Response {
  if (Math.random() > 0.5) {
    return new Response("Success!");
  }
  throw new Error("Failed!");
}