exec() now available for Containers

exec() is now available for Containers. Use this.ctx.container.exec() to start processes inside a running Container, stream standard input and output, inspect exit codes, and signal each process.

Call exec() from a class extending Container, or from another Durable Object through this.ctx.container. The associated Container must already be running.

This example starts the Container when needed, then reads its Node.js version:

src/index.jsjs

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

export class MyContainer extends Container {
	async readVersion() {
		if (!this.ctx.container.running) {
			await this.start();
		}

		const process = await this.ctx.container.exec(["node", "--version"]);
		const output = await process.output();
		const decoder = new TextDecoder();

		return {
			exitCode: output.exitCode,
			stdout: decoder.decode(output.stdout),
			stderr: decoder.decode(output.stderr),
		};
	}
}

src/index.tsts

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

export class MyContainer extends Container {
	async readVersion() {
		if (!this.ctx.container.running) {
			await this.start();
		}

		const process = await this.ctx.container.exec(["node", "--version"]);
		const output = await process.output();
		const decoder = new TextDecoder();

		return {
			exitCode: output.exitCode,
			stdout: decoder.decode(output.stdout),
			stderr: decoder.decode(output.stderr),
		};
	}
}

The command array starts an executable directly, without an implicit shell. Invoke a shell explicitly for pipes, redirects, or variable expansion.

One RPC method can coordinate multiple exec() calls in one caller-to-Durable Object round trip. It can also pass byte-oriented ReadableStream input or return streamed output with flow control.

For options and streaming examples, refer to Execute commands.