Baby Connect Project – Design Considerations

Previously, I wrote about my experience creating some automation to keep track of my baby daughter’s diapers and bottles using a service called Baby Connect. This time, I’d like to discuss some of the hurdles I faced and design choices I made. If you haven’t already read the original article, it would be a good idea to check it out first.

Why not 100% cloud?

Ideally, I would’ve loved to have the entire solution live in the cloud. Amazon Lambda is perfect for the small tasks required in this automation. Unfortunately, a Lambda function would not be able to send data to Baby Connect for two main reasons.

Native binaries

My code uses a Node.js library called nightmare to perform browser automation. Now, in general using external node libraries is possible in a Lambda function. First, you would set up a project folder locally and run npm install to load the external module. Next, zip the entire thing and upload it as the source of your Lambda function.

The trick with nightmare is, behind the scenes it uses Electron to run a headless browser session. Most node modules just contain more JavaScript code, but Electron requires the installation of native binaries, which doesn’t exactly translate to a serverless environment like Lambda.

X Window System dependency

As I mentioned, nightmare uses Electron to create a headless browser session. Now, although Electron won’t actually show a browser window, it still requires an X Window display. I got around having to run a full X11 server on my Raspberry Pi by using the X virtual framebuffer (Xvfb) package, and creating a virtual display before launching my node application.

In addition to requiring additional native binaries, this workaround also requires some setup steps before the actual node application code can be executed. Neither of these fit with the way Lambda is designed.

A note on experience

I’ve gained a lot more experience with AWS since I originally tackled this problem. For example, I learned that Lambda functions are run on Amazon Elastic Compute Cloud (EC2) instances running an Amazon Linux image.

With that knowledge, I could probably bundle the correct native binaries for Electron and Xvfb into my Lambda function, and modify my application to have it create the virtual display itself. That would, however, introduce the additional risk of future incompatibility as AWS continues to update the Amazon Linux image Lambda uses.

Also, my daughter has gotten older and we no longer track her diapers and bottles. There is no value in going back and reworking the solution now.

Getting a different slice of Pi

Even after mapping out the flow of events and finding all the tools to use to implement my solution, I spent a good few days frustrated over another issue. The nightmare library in my Node.js application simply wouldn’t work. I had followed the documentation and even tried the most basic examples with no luck.

Eventually, I was able to find this issue on GitHub for a different project that also uses Electron. Apparently, the native Electron binaries did not work properly on a Raspberry Pi B+ (which is the model I was using). I upgraded to a Raspberry Pi 3 and was finally able to get Electron running.

I’m not surprised I ran into issues on this project. There are always hurdles to overcome. Solving these issues was a great distraction for me during the early months of my daughter’s life. I’m glad to share the results with everyone.

I have heard that Baby Connect is planning to release an actual API at some point in the near future. This would make most of my efforts obsolete. Although that is a little frustrating, if they do release an API maybe I will revisit the project. It would be fun to see what kind of improvements I could make.

By | 2017-03-31T11:22:45+00:00 April 3rd, 2017|Cloud|0 Comments

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