All posts by Steven Uray

Automated Soylent Maker

Final Product:

Motivation:

I enjoy drinking Soylent, the popular nutritional replacement drink. It is efficient in terms of money, nutrition, and time to create/consume/clean. I do not enjoy the process of manually making Soylent, which I found myself doing dozens of times per year. This sparked the motivation to automate the process, ideally with an Arduino, which was a new technology I was interested in exploring in 2017.

General Operation:

The moving platform moves the container between the powder dispensing and mixing stations about once per minute, about 15 times, in a process that completes in about 20 minutes. Once the container is filled with water and the process starts, it can proceed unattended and finishes automatically.

Source Code:

The source code for this project is available on Github:

Notice: I deliberately did not invest a lot of time in writing Clean Code because I wanted to focus on other aspects of the project. Be advised Uncle Bob would not look kindly on the above code.

Lower Level Components:

Here is the powder dispenser, in an inoperable form, taken in a photograph at a later date. The servo is controlled by a different Arduino Uno, which then moves the slider on the powder dispenser back and forth. The LED display is there to help with correctly programming servo motor values, and the big mechanical vibrator is attached front and center to make sure the powder doesn’t bunch up and stop flowing.
The moving platform is intended to move the container between powder dispensing and blending stations. It uses a servo motor controlled by an Arduino to do this.

Major Individual Level Components:

Lessons Learned the Hard Way

1. Fine Soylent powder had a tendency to clump unexpectedly within the dispenser, causing it to stop dispensing entirely on occasion until I knocked the dispenser unit to break it free. This was eventually resolved by installing a strong mechanical vibrator to automatically clear the clumps. This in turn caused issues keeping the screws in place, as the additional vibration had a tendency to knock them out of their sockets over time.

2. Lining up the blender head and the container reliably and accurately proved surprisingly challenging. It became necessary to put screws on the moving platform so that the container would fall into a specific place each time I placed it there. Lining up the moving platform and blender correctly took many iterations, and I eventually strapped on lasers to the blender head so it was easier to visualize exactly where it would drop down.

3. Dispensing too much powder into the container in a single pass could easily create a situation where the blades became completely covered in powder, and additional dunking/spinning would not clear them. This is the primary motivation for so many passes between powder dispensing and mixing stations.

4. Originally I wanted a station in the middle that would dispense water into the container in the right amount automatically during the start of the process. This was later cut because getting the process to work at all proved more time-consuming than originally expected, partly due to the above lessons as well as a general under-scoping of the project at the outset.

Monolith to Dockerlith: Learnings from Migrating a Monolith to Docker

 

Docker Logo

NodeJS Logo

 

Like everyone’s monolith, Earnest’s is complex and was once a little bit out of control. Earnest’s monolith is involved in all major aspects of the business. It is responsible for accepting loan applications from clients, making a decision for each of those applicants, and even supporting clients after loans have been signed. These wide-ranging responsibilities mean that the monolith is really five different applications in one body of code.

Over 100 developers have contributed to its codebase since inception. The complexity of so many revisions and updates made it difficult to set up and maintain. Beyond standard npm libraries, almost a dozen different dependencies from a database to a mock SQS queue to a Hashicorp Vault instance needed to be set up correctly for it to work completely on a developer’s computer. Engineering teams had come to expect that getting this application set up on a new computer would take at least a week, and would require the assistance of multiple developers who had been at the company long enough to acquire the necessary tribal knowledge.

As an engineering team, Earnest needed a way to ensure everyone had a consistent local environment. It needed to be quick and easy to set up. Finally, the local environment should have greater parity with the CI, staging, and production environments. In order to accomplish these objectives, I turned to Docker, Docker Compose, and The Go Script pattern.

Dockerlith Architecture

I started the solution by addressing the shared node_modules folder between all five applications. All application containers shared the same node_modules folder inside a Docker volume. Any of these containers could be started in any order and update the npm dependencies. Therefore it became necessary to ensure only one container could write to node_modules at a time.

While there are many ways to control the start up order of Docker containers, I chose to create a bash script that would lock file descriptors at runtime and then executed this script in the entrypoint of each container. After this script ran, it would invoke the application’s process and the application container would be usable by the developer. An application container’s Docker Compose file looks like this:

Dockerlith Docker Compose 1

Here is the entrypoint script for each application container.

So: the first time a user starts up the application containers, one of them will grab the lock and install the dependencies. The rest of the containers will wait for it to finish, see that the dependencies are valid before turning the control over to the grunt startup tasks. Dependencies are automatically checked and updated, but subsequent start ups will occur quickly and without calls to “npm install” until the dependencies change.

In the event of a container shutdown, networking failure, or Docker daemon shutdown, the lock on the file descriptor is released automatically. Developers can restart the Docker containers and continue with their workflow to recover from this unexpected failure.

In addition to the container startup synchronization system, there is a Docker image that contains the correct versions of node, npm, and other programs. Docker Compose links the application containers, a Postgres container, a mock Amazon SQS queue, and other supporting containers.

I have implemented The Go Script pattern as the last piece of the puzzle to make setting up the application, starting it, and running the tests one-step commands. This pattern is used by almost every project at Earnest, and it’s implementation in this project brings it in line with the rest of Earnest’s tooling. Developers new to the project can become productive quickly, and all developers can keep their focus on high-level goals instead of low-level implementation details.

Accomplishing these goals was time-consuming and difficult, but worth it. Team morale improved as a longstanding pain point in the daily life of Earnest software developers was eliminated. Earnest’s software developers reported that this tool increased their efficiency by an average of 32.5% when working on the monolith. On an average workday, this tool is used around 200 times by the engineering team.

 Dockerlith Usage

This was originally a post on Earnest’s engineering blog, but has been cross posted to my blog as I am the original author and did the work described in the post.

Dino Rampage (Global Game Jam 2015)

I attended Global Game Jam 2015 at the UT Austin. Austin has a thriving game development community, and I estimate at least 60-70 people turned up for the weekend. Corporate sponsors made it rain free Red Bull and pizza at various times, providing welcome refreshment/energy.

I had the pleasure of working with Tom Long, Stuart Imel, Kez Laczin, and Keith McCormic. Our game was Dino Rampage, where the player controls a schoolbus in a doomed attempt to escape a dinosaur park. It can be played here

End Run Version 2

I decided to pivot the End Run project in a new direction. The new goal of the game is to put players in an environment where every major instrument in the song has a visual that appears when it plays. The drums, for example, have fireworks appear if the player moves on a beat when there are drums. The prototype level is complete and ready to play! I recommend downloading the windows version for higher resolution and more responsive controls, but there is also a web version available.

Download Windows

Website Link

End Run

End Run is a rhythm/arcade prototype I created during May 2014 and refined in between my summer travels. Players move once per beat toward the end of the level while dodging obstacles.  After getting settled into Austin, I chose to pivot the game in a direction that would allow players to visualize and interact with the music on a deeper level.

The first three levels are refined and complete, and can be played below!

Download Windows
 
 
Screenshot Gallery: