How can I see the file system nature of my Node.js Cloud Function environment?

Question

When I deploy my Cloud Function to GCP (written in Node.js), how can I see my file system environment for debugging purposes? What if I want to know what my current directory is or what files are present alongside my application?

Answer 1

When we deploy a Cloud Function, the full Node.js environment is present. We can run arbitrary Node.js logic within. This includes logging information which will then show in the Stackdriver logs. We can thus log our current working directory path as well as a list of all the files in our current directory. We can use this as a diagnostic aid. Here is an example:

const fs = require('fs');
exports.helloWorld = (req, res) => {
  console.log(`CWD: ${process.cwd()}`);
  fs.readdir('.', function (err, files) {
    if (err) {
        return console.log('Unable to scan directory: ' + err);
    } 
    files.forEach(function (file) {
        console.log(file); 
    });
    res.status(200).send('Done!');
  });
};

You can incorporate this logic in your own apps for testing.

And here is an alternate version which shows a recursive listing of all files and sub directories.

const fs = require('fs');
const walk = function(dir) {
  var results = [];
  var list = fs.readdirSync(dir);
  list.forEach(function(file) {
    file = dir + '/' + file;
    var stat = fs.statSync(file);
    if (stat && stat.isDirectory()) { 
      results = results.concat(walk(file));
    } else { 
      results.push(file);
    }
 });
 return results;
}

exports.helloWorld = (req, res) => {
  let message = req.query.message || req.body.message || 'Hello World!';
  console.log(`CWD: ${process.cwd()}`);
  console.log(`Dir Listing: ${walk('.')}`);
  res.status(200).send('Done!');
};

All credit to the above algorithm to node.js fs.readdir recursive directory search.