Dockerode Utils

Set of useful functions for working with dockerode.

TOC

• Installation
• API
  • pullImageAsync pull docker image and wait to finish download. You can track progress.
  • execCommand execute shell command inside a running container, returns output.
  • waitForOutput wait for specific string to appear in running container's stdout.
  • imageExists check if image with imageName already exists.
• Contribution

Installation

npm

npm install dockerode-utils --save

yarn

yarn add dockerode-utils

API

pullImageAsync(dockerode, imageName, onProgress?)

pullImageAsync(dockerode: Dockerode, imageName: string, onProgress?: (output: string) => void): void

Will pull docker image, you can wait for finish or track a progress. If you forget to specify :tag, it'll download :latest

/**
 * Example how to pull alpine:latest image from dockerhub
 */
import * as Dockerode from 'dockerode';
import { pullImageAsync } from 'dockerode-utils';
 
const dockerode = new Dockerode();
await pullImageAsync(dockerode, 'alpine:latest');

execCommand(container, cmd)

execCommand(container: Dockerode.Container, cmd: string[]): string[]

Execute shell command in container and returns output as string[].

/**
 * Print list of env from docker container
 */
import * as Dockerode from 'dockerode';
import { execCommand } from 'dockerode-utils';
 
// first, we need to create a container
const dockerode = new Dockerode();
const alpineContainer = await dockerode.run('alpine', [], {}, null);
 
const envList = execCommand(alpineContainer, ['env']);
console.log(envList);
 
// command with argument
const envList2 = execCommand(alpineContainer, ['env', '--help']);
console.log(envList2);

waitForOutput(container, predicate, timeout = 15000)

waitForOutput(container: Dockerode.Container, predicate: (output: string) => boolean, timeout: number = 15000)

Wait for specific output from container. Useful, when you're working with container, in which is running daemon and you have to wait for specific output/line to appears in container.

/**
 * Example with waiting for specific output.
 * Here, we're waiting for 'InnoDB: 5.7.18 started' to appears in mysql container
 * only after that, we know that mysql container is fully initialized and we can
 * continue executing commands
 */
 import * as Dockerode from 'dockerode';
 import { waitForOutput } from 'dockerode-utils';
 
const dockerode = new Dockerode();
const mysqlContainer = await dockerode.run('mysql:5.7.18', [], {}, null);
 
await waitForOutput(mysqlContainer, (line) => line === 'InnoDB: 5.7.18 started');
console.log('MySql db started');

imageExists(dockerode, ...imageNames)

imageExists(dockerode: Dockerode, ...imageNames: string | string[]): boolean

Check if images with imageNames exist. You can check more than one image at once, like imageExists(dockerode, ['mongo', 'mysql']) or only one imageExists(dockerode, 'mongo'). In case, you won't define :tag it'll check if any image with imageName prefix exists.

Contribution

Feel free to contribute with useful function that you're using daily and it can be helpful for others.