All posts

MinIO server gauge with Raspberry Pi

Today we’ll take a look at an IoT pressure gauge for your MinIO server. This is a cool hack built by Alex Ellis with the Raspberry Pi, Docker and MinIO.

After contributing code to the Open-Source MinIO project to enable webhooks Alex wanted visualize the traffic passing through his server. His hack shows the rate that objects get uploaded to a live server.

In this post we give a live demo, then go over the bill of materials, a high-level diagram and finally link out to the source-code on Github so you can try this for yourself.

Live demo:

Here is a video of the Pressure Gauge in action.

Bill of materials

  • 1x Raspberry Pi Zero with 40-pin male header
  • 1x 8GB class 10 micro-SD card
  • 1x Pimoroni Blinkt! 8-LED add-on
  • USB-OTG to USB-A cable
  • MinIO server running in the cloud, on-prem or on your laptop.

The Blinkt! costs around 5USD and was created by Pimoroni in the UK as a cheap and effective output for IoT projects. Through a simple Python or Golang library you can program 8 RGB LEDs and build fun projects.

Alex put together a talk and demo for Dockercon last year called Protecting the Datacenter with IoT. It consisted of half a dozen Raspberry Pi sensors and Blinkts all connected through Docker and Redis to provide real-time alerts about thermal issues and tampering straight from your server room. You can see a live video of the demo and talk from Container Camp, London here.

Technical overview:

  • Any compatible S3 client (such as the MinIO CLI) uploads files to an S3 bucket
  • The MinIO server (running on the cloud, on-prem, your laptop or an RPi) generates a webhook over HTTP/s
  • A Node.js/Express.js microservice running on the RPi picks up the webhook and increments a live Redis counter objects_put
  • A Python program polls Redis constantly and updates the colors on the Pi depending on how high the objects_put rate is


  • How does the pressure drop? Redis has an auto-expiry command called EXPIRE — this is used to turn the counter into a rolling rate.
  • How is the code deployed on the RPi? The three moving parts — Node.js, Python and Redis are all containerized with Docker and can be setup in one shot with Docker Compose.
  • How do you enable webhooks on MinIO? See the introductory blog post on MinIO webhooks.
  • Can I run the MinIO server directly on my Raspberry Pi? MinIO is available through Docker or as a stand-alone binary for most common platforms including all current models of the Raspberry Pi, Pine64 and other System-on-Chip boards (SoCs).

Next steps:

Head over to the MinIO quickstart guide and get up and running with Docker in one command.