Why Greengrass?

Each ESP32-S3ESP32-S3
Espressif ESP32-S3 — Wi‑Fi microcontroller used here as the Greengrass client device (not a second core). has an IoT certificate. You can publish straight to IoT CoreIoT Core
AWS IoT Core — cloud MQTT and device identity service. Client devices use it for discovery; the MQTT bridge forwards zone topics here, where IoT rules route them to other AWS services., or connect to a local Greengrass core first. This lab uses the hub.

Topologies

Direct IoT Core

ESP32

ESP32

→

IoT Core

Each board talks to the cloud; decisions run in the cloud or on every MCU.

Greengrass hubthis lab

ESP32

ESP32

→

NUC core

⇢

IoT Core

Boards decide on the LAN via the core; cloud mirror is optional.

• Direct: fewer moving parts; no local decisions if the cloud is unreachable.
• Hub: closed loop on the LAN, shared components — but the core is a single point of failure.

Tradeoffs

Need	Direct IoT Core	Greengrass hub
Local decide with cloud down / high RTT	Fails or needs on-device logic	Closed loopClosed loop Sense → decide → actuate on the LAN — zone sensor events on gg-edge/sensor become actuator commands on gg-edge/actuator via a custom component. on the LAN
Many boards, one place for policy / ML	Logic in cloud or on every MCU	Components on the corecore Greengrass core device — the Linux host running Nucleus (this lab: Intel NUC6CAY). Client devices discover and connect to it.
Cloud-managed edge software versions	Device OTA only	ComponentComponent Greengrass component — a versioned unit of software on the core (AWS public components or custom recipes such as GgEdgeLoop / ZoneAnomaly). deployments + config merge
Simplest cloud MQTT telemetry	Fewer moving parts	Extra Nucleus + broker stack
Hub host dies	Boards can still reach cloud (if online)	Local path through that core is a single point of failure

Single point of failure

One NucleusNucleus
Greengrass Nucleus — the edge runtime on the core device. Installs components, talks to AWS, and hosts the local client-device stack. + MoquetteMoquette
aws.greengrass.clientdevices.mqtt.Moquette — local MQTT broker on the core. Not Mosquitto; client devices connect here over mTLS. on one NUC is a SPOF for local MQTT and for components that decide there. This walkthrough does not build multi-core HA.

Nucleus lite

AWS also offers Nucleus lite for constrained hosts. This lab uses classic Nucleus on Ubuntu x86. See the developer guide if you need lite later.

Next: Identities.