@travetto/command

Command

Support for executing complex commands at runtime.

Install: @travetto/command

npm install @travetto/command

# or

yarn add @travetto/command

The command module provides the necessary foundation for calling complex commands at runtime. Additionally special attention is provided to running docker containers.

Docker Support

Docker provides a unified way of executing external programs with a high level of consistency and simplicity. For that reason, the framework leverages this functionality to provide a clean cross-platform experience. The docker functionality allows you to interact with containers in two ways:

• Invoke a single operation against a container
• Spin up a container and run multiple executions against it. In this format, the container, once started, will be scheduled to terminate on Shutdown of the application.

Code: Launching nginx and wait for connect

import { DockerContainer, CommandUtil } from '@travetto/command';

export class NginxServer {
  #port: number;
  container: DockerContainer;

  constructor(
    port = Math.trunc(Math.random() * 40000) + 10000
  ) {
    this.#port = port;
    this.container = new DockerContainer('nginx:latest')
      .exposePort(this.#port, 80)
      .forceDestroyOnShutdown();
  }
  start() {
    this.container.run();
    CommandUtil.waitForPort(this.#port);
    console.log('Ready!');
  }

  async stop() {
    await this.container.stop();
    console.log('Stopped');
  }
}

Command Service

While docker containers provide a high level of flexibility, performance can be an issue. CommandOperation is a construct that wraps execution of a specific child program. It allows for the application to decide between using docker to invoke the child program or calling the binary against the host operating system. This is especially useful in environments where installation of programs (and specific versions) is challenging.

Code: Command Service example, using pngquant

import { createWriteStream, createReadStream } from 'node:fs';
import { pipeline } from 'node:stream/promises';

import { CommandOperation } from '@travetto/command';
import { ExecUtil } from '@travetto/runtime';

export class ImageCompressor {
  converter = new CommandOperation({
    containerImage: 'agregad/pngquant:latest',
    localCheck: ['pngquant', ['-h']]
  });

  async compress(img: string) {
    const proc = await this.converter.exec('pngquant', '--quality', '40-80', '--speed 1', '--force', '-');
    const out = `${img}.compressed`;

    await Promise.all([
      // Feed into process
      pipeline(createReadStream(img), process.stdin),
      // Write output
      pipeline(proc.stdout!, createWriteStream(out))
    ]);

    await ExecUtil.getResult(proc);
  }
}

CLI - service

The module provides the ability to start/stop/restart services as docker containers. This is meant to be used for development purposes, to minimize the effort of getting an application up and running. Services can be targeted individually or handled as a group.

Terminal: Command Service

$ trv service --help

Usage: service [options] <action:restart|start|status|stop> [services...:string]

Options:
  -h, --help  display help for command

Available Services
--------------------
 * dynamodb@2.0.0
 * elasticsearch@8.9.1
 * firestore@latest
 * mongodb@7.0
 * mysql@8.0
 * postgresql@15.4
 * redis@7.2
 * s3@3.1.0

A sample of all services available to the entire framework:

Terminal: All Services

$ trv service status

Service          Version    Status
-------------------------------------------------
dynamodb           2.0.0    Running 93af422e793a
elasticsearch      8.9.1    Running ed76ee063d13
firestore         latest    Running feec2e5e95b4
mongodb              7.0    Running 5513eba6734e
mysql                8.0    Running 307bc66d442a
postgresql          15.4    Running e78291e71040
redis                7.2    Running 77ba279b4e30
s3                 3.1.0    Running fdacfc55b9e3

Defining new Services

The services are defined as plain typescript files within the framework and can easily be extended:

Code: Sample Service Definition

import type { CommandService } from '@travetto/command';

const version = process.env.MONGO_VERSION || '4.4';

export const service: CommandService = {
  name: 'mongodb',
  version,
  port: 27017,
  image: `mongo:${version}`
};