---
description: Execute Workers code in reaction to Container status changes
title: Status Hooks
image: https://developers.cloudflare.com/og-docs.png
---

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# Status Hooks

Execute Workers code in reaction to Container status changes

Last updated Aug 28, 2026|Copy as Markdown|[View as Markdown](https://codex-container-api-docs.previews.developers.cloudflare.com/containers/examples/status-hooks/index.md)|[Agent setup](https://codex-container-api-docs.previews.developers.cloudflare.com/agent-setup/)

Use `monitor()` with the Durable Object Container API to run code after the Container exits or errors. The `Container` class adds named lifecycle hooks and an inactivity callback.

```js
import { DurableObject } from "cloudflare:workers";

export class MyContainer extends DurableObject {
	ready;

	constructor(ctx, env) {
		super(ctx, env);
		ctx.blockConcurrencyWhile(() =>
			ctx.container.setInactivityTimeout(5 * 60 * 1000),
		);
	}

	async fetch(request) {
		const container = this.ctx.container;
		if (!container.running) {
			this.ready = undefined;
		}
		this.ready ??= this.startAndMonitor().catch((error) => {
			this.ready = undefined;
			throw error;
		});
		await this.ready;

		return container.getTcpPort(4000).fetch(request);
	}

	async startAndMonitor() {
		const container = this.ctx.container;
		if (!container.running) {
			container.start();
		}

		this.ctx.waitUntil(
			container
				.monitor()
				.then(() => console.log("Container stopped"))
				.catch((error) => console.error("Container error:", error)),
		);

		const port = container.getTcpPort(4000);
		let lastError;
		for (let attempt = 0; attempt < 50; attempt++) {
			try {
				await port.fetch("http://container/");
				console.log("Container successfully started");
				return;
			} catch (error) {
				lastError = error;
				await scheduler.wait(100);
			}
		}
		throw lastError;
	}
}
```

```ts
import { DurableObject } from "cloudflare:workers";

interface Env {}

export class MyContainer extends DurableObject<Env> {
	private ready: Promise<void> | undefined;

	constructor(ctx: DurableObjectState, env: Env) {
		super(ctx, env);
		ctx.blockConcurrencyWhile(() =>
			ctx.container!.setInactivityTimeout(5 * 60 * 1000),
		);
	}

	async fetch(request: Request): Promise<Response> {
		const container = this.ctx.container!;
		if (!container.running) {
			this.ready = undefined;
		}
		this.ready ??= this.startAndMonitor().catch((error: unknown) => {
			this.ready = undefined;
			throw error;
		});
		await this.ready;

		return container.getTcpPort(4000).fetch(request);
	}

	private async startAndMonitor(): Promise<void> {
		const container = this.ctx.container!;
		if (!container.running) {
			container.start();
		}

		this.ctx.waitUntil(
			container
				.monitor()
				.then(() => console.log("Container stopped"))
				.catch((error: unknown) => console.error("Container error:", error)),
		);

		const port = container.getTcpPort(4000);
		let lastError: unknown;
		for (let attempt = 0; attempt < 50; attempt++) {
			try {
				await port.fetch("http://container/");
				console.log("Container successfully started");
				return;
			} catch (error) {
				lastError = error;
				await scheduler.wait(100);
			}
		}
		throw lastError;
	}
}
```

```ts
import { Container } from "@cloudflare/containers";

export class MyContainer extends Container {
	defaultPort = 4000;
	sleepAfter = "5m";

	override onStart() {
		console.log("Container successfully started");
	}

	override onStop(stopParams) {
		if (stopParams.exitCode === 0) {
			console.log("Container stopped gracefully");
		} else {
			console.log("Container stopped with exit code:", stopParams.exitCode);
		}

		console.log("Container stop reason:", stopParams.reason);
	}

	override async onActivityExpired() {
		console.log("Container became idle, stopping it now");
		await this.stop();
	}

	override onError(error: string) {
		console.log("Container error:", error);
	}
}
```

The `monitor()` promise in the raw API does not include an exit code or stop reason. The `setInactivityTimeout()` method does not invoke a callback when the timeout expires. Use the [Container class lifecycle hooks](https://codex-container-api-docs.previews.developers.cloudflare.com/containers/api/container-class/#lifecycle-hooks) when you need those higher-level events.

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