Nitro

name: tasks description: On-demand and scheduled (cron) tasks in Nitro, defineTask, runTask, and platform support

Tasks

Tasks are one-off runtime operations (migrations, cleanups, cache refresh). Experimental — enable the flag first. Tasks are scanned from serverDir, which must also be set.

import { defineConfig } from "nitro";

export default defineConfig({
  serverDir: "./server",
  experimental: { tasks: true },
});

Defining tasks

Files in <serverDir>/tasks/[name].ts. Nested dirs join with : (e.g. tasks/db/migrate.ts → db:migrate). Import defineTask from nitro/task (no auto-imports in v3).

import { defineTask } from "nitro/task";

export default defineTask({
  meta: {
    name: "db:migrate",
    description: "Run database migrations",
  },
  run({ payload, context }) {
    console.log("Running DB migration...");
    return { result: "Success" };
  },
});

run receives a TaskEvent with name, payload (Record<string, unknown>), and context (may include waitUntil). Return { result }.

Tasks can also be registered in config (config handler wins over a scanned file of the same name):

import { fileURLToPath } from "node:url";

export default defineConfig({
  serverDir: "./server",
  experimental: { tasks: true },
  tasks: {
    "db:migrate": { description: "Describe a scanned task" },
    // A config handler is imported as-is (NOT resolved against rootDir) — use an absolute path:
    "db:seed": {
      handler: fileURLToPath(new URL("scripts/seed.ts", import.meta.url)),
      description: "Seed the database",
    },
  },
});

Scheduled tasks (cron)

Map cron expressions to task name(s). Multiple tasks under one expression run in parallel; scheduled runs get a payload.scheduledTime timestamp.

import { defineConfig } from "nitro";

export default defineConfig({
  scheduledTasks: {
    "* * * * *": ["cms:update"],        // every minute
    "0 0 * * *": "db:cleanup",          // daily (string shorthand)
    "*/5 * * * *": ["health:check", "metrics:collect"],
  },
});

Platform support:

• dev, node_server, node_cluster, node_middleware, bun, deno_server → croner engine.

• cloudflare_module / cloudflare_pages → native Cron Triggers (wrangler config auto-generated).

• vercel → native Cron Jobs (config auto-generated; secure with CRON_SECRET).

Running tasks programmatically

import { defineHandler } from "nitro";
import { runTask } from "nitro/task";

export default defineHandler(async (event) => {
  // IMPORTANT: authenticate and validate before running!
  const payload = Object.fromEntries(event.url.searchParams);
  const { result } = await runTask("db:migrate", { payload });
  return { result };
});

runTask throws a 404 if the task doesn't exist, 501 if it has no handler; errors from run propagate to the caller.

Background work with waitUntil

import { defineTask } from "nitro/task";

export default defineTask({
  run({ context }) {
    const promise = fetch("https://api.example.com/sync");
    context.waitUntil?.(promise);
    return promise.then(() => ({ result: "ok" }));
  },
});

Dev server tools

While nitro dev runs:

• GET /_nitro/tasks — list available tasks + scheduled tasks.

• GET|POST /_nitro/tasks/:name — execute (payload from query and/or JSON body under "payload").

• CLI: nitro task list and nitro task run db:migrate --payload "{}".

Key Points

• Requires experimental.tasks: true and serverDir set; defineTask and runTask both come from nitro/task (no auto-imports in v3).

• Each task has one running instance — parallel calls of the same name share a single run/result.

• scheduledTasks cron config is translated to native triggers on Cloudflare and Vercel automatically.

<!-- Source references: - https://nitro.build/docs/tasks -->