This code checks for the presence of Docker on the system by executing the docker ps command and signals completion with a message indicating whether Docker is installed or not.

Run example

npm run import -- "install Docker on Mac"

install Docker on Mac

$.async();
var exec = require('child_process').exec;
var installed = false;
var docker = exec('docker ps', (err, stdout, stderr) => {
    if (stdout.indexOf('not found') > -1) {
        $.done('Docker not found, installing');
    } else {
        installed = true;
        $.done('Docker is already installed');
    }
});

// Import required modules
const { fork } = require('child_process');
const $ = require('./common');

// Function to check Docker installation
async function checkDockerInstallation() {
  // Use child_process to execute the 'docker ps' command
  const dockerProcess = fork('docker ps', [], {
    env: process.env,
    stdio: ['pipe', 'pipe', 'pipe'],
  });

  // Wait for the process to finish
  return new Promise((resolve, reject) => {
    dockerProcess.on('message', (message) => {
      if (message.includes('not found')) {
        resolve('Docker not found, installing');
      } else {
        resolve('Docker is already installed');
      }
    });

    dockerProcess.on('error', (err) => {
      reject(err);
    });
  });
}

// Check Docker installation and return the result
async function main() {
  try {
    const result = await checkDockerInstallation();
    $.done(result);
  } catch (err) {
    $.done(`An error occurred: ${err}`);
  }
}

// Call the main function
main();

This code snippet checks if Docker is installed on the system and signals completion based on the result.

Breakdown:

1. $.async();:

   • This line likely initializes an asynchronous operation using a variable $ (possibly a custom function or library).

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

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

3. var installed = false;:

   • Initializes a boolean variable installed to false, assuming Docker is not installed initially.

4. var docker = exec('docker ps', (err, stdout, stderr) => { ... });:

   • Executes the command docker ps (which lists running Docker containers) using exec().
   • The callback function handles the result:
     • err: Error object if any occurred during execution.
     • stdout: Standard output from the command (the list of containers).
     • stderr: Standard error output (if any).

5. Inside the callback:

   • if (stdout.indexOf('not found') > -1) { ... }:
     • Checks if the output contains the string "not found", indicating Docker is not installed.
     • If found, calls $.done('Docker not found, installing') to signal the asynchronous operation with a message.
   • else { ... }:
     • If "not found" is not found, it means Docker is installed.
     • Sets installed to true.
     • Calls $.done('Docker is already installed') to signal completion with a success message.