Watcher for NodeJS

Learn how to configure Watcher for NodeJS for use with Filebase.

What are Watchers for NodeJS?

Watcher for NodeJS are modules or tools that allow developers to monitor changes in files or directories and execute code in response to those changes.

NodeJS provides a built-in module called "fs" (file system) that allows developers to interact with the file system. Watchers for NodeJS use the "fs" module to monitor changes in files or directories by continuously checking for modifications, deletions, and additions.

Read below to learn how to use Watcher for NodeJS with Filebase.

Prerequisites:

• Install Node.js and npm.

• Download and install an IDE of your choice, such as VSCode.

• Sign up for a free Filebase account.

• Have your Filebase Access and Secret Keys. Learn how to view your access keys here.

1. First, we need a Filebase IPFS bucket.

To do this, navigate to console.filebase.com. If you don’t have an account already, sign up, then log in.

2. Select ‘Buckets’ from the left sidebar menu, or navigate to console.filebase.com/buckets.

Select ‘Create Bucket’ in the top right corner to create a new bucket.

3. Enter a bucket name and choose the IPFS storage network to create the bucket.

Bucket names must be unique across all Filebase users, be between 3 and 63 characters long, and can contain only lowercase characters, numbers, and dashes.

4. Next, download and install S3FS-FUSE on a Linux or macOS system.

5. Set up an Access Key file for use with S3FS-FUSE.

Set up a credentials file for S3FS at ${HOME}/.passwd-s3fs. You will need to save your Filebase Access and Secret keys to this file and give it owner permissions. You can do so with the following commands:

echo ACCESS_KEY_ID:SECRET_ACCESS_KEY > ${HOME}/.passwd-s3fs

chmod 600 ${HOME}/.passwd-s3fs

ACCESS_KEY_ID is your Filebase Access key, and SECRET_ACCESS_KEY is your Filebase Secret key. For more information on Filebase access keys, see here.

6. Mount your bucket.

You can mount a Filebase IPFS bucket with the command:

s3fs mybucket /path/to/mountpoint -o passwd_file=${HOME}/.passwd-s3fs -o url=https://s3.filebase.com

• mybucket: name of your Filebase bucket

7. Next, install the following packages:

npm install chokidar fs-extra

8. Next, create the following directory structure:

9. In the services directory, create a new file called observer.js.

Insert the following code into this file:

const chokidar = require('chokidar');
const EventEmitter = require('events').EventEmitter;
const fsExtra = require('fs-extra');

class Observer extends EventEmitter {
  constructor() {
    super();
  }

  watchFolder(folder) {
    try {
      console.log(
        `[${new Date().toLocaleString()}] Watching for folder changes on: ${folder}`
      );

      var watcher = chokidar.watch(folder, { persistent: true });

      watcher.on('add', async filePath => {
        if (filePath.includes('error.log')) {
          console.log(
            `[${new Date().toLocaleString()}] ${filePath} has been added.`
          );

          // Read content of new file
          var fileContent = await fsExtra.readFile(filePath);

          // emit an event when new file has been added
          this.emit('file-added', {
            message: fileContent.toString()
          });

          // remove file error.log
          await fsExtra.unlink(filePath);
          console.log(
            `[${new Date().toLocaleString()}] ${filePath} has been removed.`
          );
        }
      });
    } catch (error) {
      console.log(error);
    }
  }
}

module.exports = Observer;

10. Then, create a new file called server.js that contains the following code:

const Obserser = require('./services/observer');

var obserser = new Obserser();

const folder = '/path/to/watch';

obserser.on('file-added', log => {
  // print error message to console
  console.log(log.message);
});

obserser.watchFolder(folder);

Replace /path/to/watch with the file path of your mounted Filebase bucket.

11. Then, in the project’s root directory, run the following command:

node src/server.js

12. Now, move a folder or file into your mounted Filebase bucket directory.

The move will be logged by the watcher script:

[2/21/2023, 11:01:51 AM] Watching for folder changes on: /Users/jessiemongeon/filebase-bucket

[2/21/2023, 11:01:51 AM] /Users/jessiemongeon/filebase-bucket/image.png has been added.