ESP32 and Programming – Part 2

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Jun 262017
 

Reading all this nice stuff about TDD. Using the Espruino GUI suddenly feels limiting. It’s great for testing and small things less than 1000 lines, but once you want modules and testing, it fails as it’s simply not made for that.

But there’s a fix, at least for me: https://github.com/haraldkubota/esp32

In short:

  • browserify to make a single JavaScipt file out of modules
  • Jest for testing
  • make to bundle it all together (ok, I do use npm too, but make it nicer IMHO)
  • netcat to upload the code

ESP32 with BME280, showing its measured data with sparklines

The sparkline as well as the circular buffer code it uses was attempted to be written via TDD. I think I failed partially here, but I still have plenty tests. When restructuring the code I was happy about the tests as they confirmed all is still working! Hooray for tests!

Google Cloud, Authentication, Storage and NodeJS

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Jun 042017
 
Google Cloud, Authentication, Storage and NodeJS

How to use Cloud Storage from NodeJS? It’s actually easy once you found the libraries to use and a sample which works. But finding this was a long journey which took most of a day. Here was the most useful article of Sebastien having had the same problem. Shortly later I found this: https://googlecloudplatform.github.io/google-cloud-node/#/docs/storage/1.1.0/storage which helped a lot.

The short summary here in the hope that someone might read this and get a simple working example of NodeJS+Google Cloud Storage.

Pre-Requisite: Access

On the Google Cloud Console, go to IAM & Admin, create a Service Account, and create a key for it. Keep this key. It’s the JSON key in the keyFilename. This plus the projectID plus permissions is all you need to get access.

Under IAM you change the role of the new service account to Storage Admin to see all buckets. if you only want to connect to one bucket, use Storage Object Admin. Or less depending on what you need.

BTW updating permissions is almost instantly.

Task 1: See Buckets

This is the NodeJS program running on my home PC. I split it into 3 parts, but it’s really one file

The service accounts needs Storage Object Admin permississions for this.

var gcs = require('@google-cloud/storage')({
 projectId: 'some-thing-12345',
 keyFilename: './KEY.json'  // absolute path ok too
});
// GOOGLE_APPLICATION_CREDENTIALS=$keyFilename was not needed
// contrary to some documentation

gcs.getBuckets(function(err, buckets) {
 if (!err) {
  buckets.forEach(function(value){
  console.log("name: "+value.metadata.name);
  console.log("location: "+value.metadata.location);
  }); 
 } else {
  console.log(err);
 }
});

2. Look Inside Buckets

Service account needs Storage Object Viewer (read-only) resp. Creator (read/write).

// List contents of bucket 'some-test-1'

var wt1 = gcs.bucket('some-test-1');

wt1.getFiles(function(err, files) {
 if (!err) {
  files.forEach(x=>{console.log("Name: "+x.name)});
  // files is an array of File objects.
 } else {
  console.log(err);
 }
});

3. Access Files in a Bucket

Service account needs Storage Object Viewer (read-only) resp. Creator (read/write)

// Download a file (resp. create a read-stream)

var fs = require('fs');
var remoteFile = wt1.file('f1/a1.sh');
var localFilename = 'test-a1.sh';

remoteFile.createReadStream()
 .on('error', function(err) {
  console.log(err);
  })
 .on('response', function(response) {
 // Server connected and responded with the specified status and headers.
  })
 .on('end', function() {
  // The file is fully downloaded.
  })
 .pipe(fs.createWriteStream(localFilename));