Retrieving SFTP listings asynchorously in Node.js

I'm trying to retrieve SFTP listings using Node, from multiple servers. I'm using the ssh2-sftp-client library, and I'm trying to handle the asynchronous connections using a futzed Promise.all().

The SFTP servers are stored in a config file (servers.config) like this:

{
  "myhost1": {
    "host": "sftp.myhost1.com",
    "port": "22 ",
    "username":  "userid1",
    "password": "password1"
  },
  "myhost2": {
    "host": "sftp.myhost2.com",
    "port": "22 ",
    "username":  "userid2",
    "password": "password2"
  },
  ...
}

My code looks like this...

#!/node
let fs = require('fs');
let Client = require('ssh2-sftp-client');

// which servers should we process?
const serverList = fs.readFileSync('./servers.config', {encoding:'utf8', flag:'r'});
const servers = JSON.parse(serverList);

const servers_to_process = Object.keys(servers);

function getDirectoryListing(config) {
  let sftp = new Client();
  sftp.connect(config)
    .then(() => {
      return sftp.list('/');
    })
    .then(data => {
      console.log('Data retrieved for: ',config.host);
      //console.log(data);  // Line B
      sftp.end();
      return data;
    })
    .catch(err => {
      console.log('Error for: ',config.host);
      return [];
    });
}


const processes_to_run = [];

// generate array of promises to run
servers_to_process.forEach( key => {
    log('==========================');
    log("Provider: "+key+"; "+timestamp);
    processes_to_run.push(getDirectoryListing(servers[key]));
  });


// wait for all the promises to resolve...
Promise.allSettled(processes_to_run).
  then((results) => results.forEach((result) => console.log(result)));

What I'm not getting is any console logged data from line A... but if I uncomment Line B, I get each listing, asynchronously.

The output looks something like this:

JSON file read correctly
==========================
Provider: myhost1; 01/06/2021, 14:57:25
==========================
Provider: myhost2; 01/06/2021, 14:57:25
{ status: 'fulfilled', value: undefined }
{ status: 'fulfilled', value: undefined }
Data retrieved for:  sftp.myhost1.com
Data retrieved for:  sftp.myhost2.com

So, clearly I'm dropping the ball on returning the data from the promises...

Is this the correct approach to getting all the listings into array, prior to processing? Is there a cleaner approach, given the asynchronous nature of the SFTP list fetching?

You need to actually return the promise from your function - getDirectoryListing() isn't returning anything. Thus, you are passing an array full of undefined to Promise.allSettled()

Try this:

function getDirectoryListing(config) {
  let sftp = new Client();
  return sftp.connect(config)
    .then(() => {
    // ...stuff
}