Restroom hacks

Datadog built an office bathroom-availability monitor to reduce contention without compromising privacy or existing door functionality. Raspberry Pi 2 devices, GPIO-connected sensors, and simple Unix tools provided a low-maintenance way to report whether bathrooms were occupied. The project showed that the hardest parts were adapting to varied real-world hardware, mounting sensors cleanly, and dealing with unreliable Wi-Fi—not writing software.

Project Goals

• Avoid intrusive monitoring:
  • No cameras or sensors that could feel invasive.
• Provide reliable occupancy information with minimal false positives and negatives.
• Use door-lock status where possible as the occupancy signal.
• Avoid interfering with existing locks and doors.
• Keep devices secure, professional-looking, easy to maintain, and remotely updateable.
• Treat the project as a fun hardware experiment.

Adapting to Different Bathrooms

• Bathrooms differed significantly in:
  • Lock styles, including push-button handles and rotary stall locks.
  • Number of rooms or stalls.
  • Availability and location of power outlets.
  • Wi-Fi quality, especially near concrete walls and older electrical equipment.
• These variations required different sensor designs rather than one universal installation.

Raspberry Pi and Sensor Hardware

• Raspberry Pi 2 Model Bs served as the project’s controllers because they:
  • Ran Linux.
  • Supported Wi-Fi and SSH administration.
  • Were compact enough to conceal.
• The team used several sensor types:
  • Magnetic reed switches for detecting door position.
  • Pin switches for detecting sliding stall-lock positions.
  • Photoresistors were purchased as a possible way to detect darkness but were not needed in the MVP.
• For push-button locks, reed switches detected whether the door was open or closed. Although this could theoretically misreport a closed but unoccupied bathroom, it worked reliably in practice.
• Stall-lock sensors were hidden inside hollow metal panels. Automotive-style pin switches were mounted using simple carved wooden blocks that contacted the sliding lock without obstructing it.
• Wiring was concealed in wiremolding, with Raspberry Pis placed inside outlet boxes where possible.

GPIO and Unix-Based Monitoring

• Raspberry Pi GPIO pins were accessed through files in /sys/class/gpio/.

• A Python script read sensor values and translated them into bathroom availability.

• Configuration handled differences between normally open and normally closed sensors.

• The service was exposed through tcpserver and managed with daemontools.

• A basic command-line client could query status with Netcat, for example:

  nc 11.bathrooms.datadog-internal.com 50
  

Making Availability Easy to Use

• Employees could check status from the command line.
• Some added bathroom availability to TextBar.
• Datadog dashboards displayed bathroom status throughout the New York office.
• The implementation required very little code; most effort went into sensor selection, physical installation, and network troubleshooting.

The project demonstrates that inexpensive, hackable hardware combined with simple Linux tools can solve a practical office problem. For similar systems, prioritize non-intrusive sensors, flexible installation designs, and secure remote management; the resulting software can remain remarkably small.