This project is the result of an afternoon hackathon we ran where I work, the objectives of which were two fold:
* Learn how to write a NodeJS app and deploy it to Google AppEngine
* Connect the plant I have on my desk to the internet
Since creating it I've migrated the project away from AppEngine and on to [Glitch](https://glitch.com) instead.
How Does It Work?
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The hardware is built around a NodeMCU, which is an Arduino-compatible microcontroller with integrated WiFi. This is connected to a simple analog soil moisture sensor that's inserted into the soil itself. The moisture sensor came with a little circuit to convert the analog signal to a digital one, but it never worked so we threw it away.
The arduino code takes a reading every hour and sends it to the app on Glitch, where it gets stored in a SQLite database. Once a week a cleanup job is triggered by [cron-job.org](https://cron-job.org) to remove readings older than 90 days from the database.
Both the creation of a new reading and the cleanup cronjob expect that a secret key be included in order to authenticate the request.
