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ESP32 + AWS IoT + Terraform + GenAI: Building a Smart Home Inventory System in One Night

ESP32 + AWS IoT + Terraform + GenAI: Building a Smart Home Inventory System in One Night

How I built a smart pantry inventory system with ESP32 + AWS IoT Core + Lambda + DynamoDB in one Monday night — from first breadboard to live dashboard. Zero cloud cost, full serverless, real-time MQTT.

Ricardo Gulias

AWS Golden Jacket | Kiro Ambassador 🟣 | Founder & Global Lead — Golden Jackets

From Zero to AWS IoT in One Night — Building a Smart Pantry with ESP32

How I went from "I don't know how to put this on a breadboard" to seeing real-time messages on AWS IoT Core — in a single Monday night.

The Problem

I buy groceries. I forget what I have at home. I buy duplicates. My wife gets annoyed.
Sound familiar?
I wanted a system that tracks everything entering and leaving my pantry — automatically. Scan a barcode when you put something in, scan when you take it out. The system keeps count and tells you what to buy.
Simple concept. But I wanted it serverless, IoT-native, and AI-powered — running on AWS for less than $1/month.

The Stack

  • ESP32 — $8 microcontroller with WiFi + Bluetooth
  • AWS IoT Core — MQTT broker with mutual TLS authentication
  • Lambda — processes scan events
  • DynamoDB — single-table design for inventory
  • Bedrock (coming soon) — generates smart shopping lists
  • Terraform — infrastructure as code
  • GitHub Actions — CI/CD
Total AWS cost: $0/month (free tier covers everything).

The Journey

8:50 PM — Unboxing

I had never touched a microcontroller before. The ESP32 arrived in an antistatic bag. The breadboard was a white plastic board with holes. I had no idea which end was up.

9:00 PM — First Signs of Life

Plugged the ESP32 into the breadboard (straddling the center channel — I had to ask what that meant). Connected a micro-USB cable. A red LED turned on. The computer recognized it as COM3 (CH9102 chip).

9:15 PM — Blink!

Compiled a simple blink firmware using PlatformIO on WSL, flashed it via esptool on Windows PowerShell (WSL can't access USB directly — lesson learned). The blue LED started blinking. First microcontroller ever programmed. ✅

9:40 PM — WiFi Connected

Updated the firmware to connect to my home WiFi. Serial monitor showed:
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Connecting to Lippi... connected!
WiFi connected! IP: 192.168.15.17

9:50 PM — AWS IoT Core Connected

Created an X.509 certificate via AWS CLI, embedded the certs in the firmware, established mutual TLS connection to AWS IoT Core. The serial monitor showed:
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Connecting to AWS IoT... connected!
Published to stockhome/dev01/status

9:55 PM — The Magic Moment

Opened the MQTT Test Client in the AWS Console, subscribed to stockhome/#, and there it was:
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{
"status": "online",
"device": "stockhome-dev01"
}
A message from the ESP32 sitting on my desk, arriving in the AWS cloud in real-time. From zero to cloud in one hour.

10:15 PM — End-to-End Flow

Fixed the IoT Rule permission (the Lambda couldn't be invoked — classic missing lambda:InvokeFunction permission). Published a test scan message. Checked DynamoDB:
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{
"PK": "HOUSEHOLD#h001",
"SK": "PRODUCT#7891234567890",
"name": "Banana",
"current_stock": 1,
"mode": "IN"
}
Full pipeline working: ESP32 → IoT Core → IoT Rule → Lambda → DynamoDB ✅

11:00 PM — Live Dashboard

Created a Lambda Function URL serving both HTML and API endpoints over HTTPS. The dashboard pulls real data from DynamoDB — products, stock levels, alerts. The admin panel shows a Leaflet map with my device's location and real-time status.

Architecture

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ESP32 (WiFi + Certs)
│
│ MQTT over TLS (port 8883)
▼
AWS IoT Core
│
│ IoT Rule (SELECT * FROM 'stockhome/+/scan')
▼
Lambda ─ process_scan
│
│ PutItem / UpdateItem
▼
DynamoDB ─ Single-Table Design
│
│ Query (PK = HOUSEHOLD#h001)
▼
Lambda Function URL ─ API + Dashboard
│
│ HTTPS
▼
Browser

Lessons Learned

  1. WSL can't access USB serial ports — use esptool directly on Windows PowerShell
  2. Always flash bootloader + partitions + firmware — flashing only the app binary causes boot loops
  3. IoT Rule → Lambda needs explicit permission — lambda:InvokeFunction from iot.amazonaws.com
  4. Lambda Function URLs need TWO permissions — InvokeFunctionUrl AND InvokeFunction
  5. Mixed content kills you — serve HTML and API from the same HTTPS endpoint

What's Next

  • Barcode scanner (GM67 module arriving from China) — real product scanning
  • Load cell (HX711 + 5kg cell) — weight-based inventory tracking
  • Bedrock AI — smart shopping list generation based on consumption patterns
  • WhatsApp alerts — "You're out of coffee!" via Z-API

Open Source

The full project is on GitHub: ricardogulias/stockhome 
Stack: ESP32 (C++) + Python 3.12 + Terraform + DynamoDB + IoT Core + Lambda
Built in one night with an ESP32, a breadboard, and AWS. Total cost: R$40 in hardware + $0/month in cloud. Sometimes the best projects start at midnight on a Monday. 🚀
# aws-iot# aws-iot-core# serverless# ai-for-developers# aws-iot-device-management
Any opinions in this article are those of the individual author and may not reflect the opinions of AWS.
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