This code downloads the Docker installer from the Docker website and saves it to the current working directory, notifying a task manager upon completion.

Run example

npm run import -- "Where do I download the Windows Docker installer"

Where do I download the Windows Docker installer

$.async();
var exec = require('child_process').exec;
var http = require('https');
var fs = require('fs');
var dockerLoc = path.join(process.cwd(), 'InstallDocker.msi');
var downloads = http.get('https://download.docker.com/win/stable/InstallDocker.msi', (r) => {
    r.pipe(fs.createWriteStream(dockerLoc)).on('finish', () => {
        $.done('downloaded InstallDocker.msi');
    });
});

// Import required modules and assign them to variables for better readability
const { exec } = require('child_process');
const axios = require('axios');
const fs = require('fs');
const path = require('path');

// Define constants for clarity
const DOCKER_MSI_URL = 'https://download.docker.com/win/stable/InstallDocker.msi';
const DOCKER_MSI_DESTINATION = path.join(process.cwd(), 'InstallDocker.msi');

// Function to download Docker MSI file asynchronously
async function downloadDockerMsi() {
  try {
    // Send GET request to download the MSI file
    const response = await axios.get(DOCKER_MSI_URL, { responseType:'stream' });
    
    // Write the response stream to a file
    const writer = fs.createWriteStream(DOCKER_MSI_DESTINATION);
    response.data.pipe(writer);
    
    // Wait for the write operation to finish
    await new Promise((resolve, reject) => {
      writer.on('finish', resolve);
      writer.on('error', reject);
    });
    
    // Log a message to indicate the download is complete
    $.done('downloaded InstallDocker.msi');
  } catch (error) {
    // Log any errors that occur during the download process
    $.error('Error downloading Docker MSI:', error);
  }
}

// Call the download function
downloadDockerMsi();

This code downloads the Docker installer (InstallDocker.msi) from the official Docker website and saves it to the current working directory.

Here's a breakdown:

1. $.async();:

   • This line likely initializes an asynchronous operation, possibly related to a task runner or workflow manager.

2. var exec = require('child_process').exec;:

   • Imports the exec module from the child_process library, which allows executing shell commands.

3. var http = require('https');:

   • Imports the https module for making HTTPS requests.

4. var fs = require('fs');:

   • Imports the fs module for file system operations.

5. var dockerLoc = path.join(process.cwd(), 'InstallDocker.msi');:

   • Constructs the full path to the downloaded installer file (InstallDocker.msi) by joining the current working directory (process.cwd()) with the filename.

6. var downloads = http.get('https://download.docker.com/win/stable/InstallDocker.msi', (r) => { ... });:

   • Initiates an HTTPS GET request to download the Docker installer from the specified URL.
   • The callback function (r) => { ... } is executed when the response is received.

7. r.pipe(fs.createWriteStream(dockerLoc)).on('finish', () => { ... });:

   • Pipes the downloaded data from the response object (r) to a write stream created for the specified file location (dockerLoc).
   • The on('finish', () => { ... }) event listener is triggered when the writing process is complete.

8. $.done('downloaded InstallDocker.msi');:

   • Signals the completion of the download task, likely to the task runner or workflow manager.

In essence, this code downloads the Docker installer from the internet and saves it to the current working directory, indicating successful completion.