"unable to get local issuer certificate" Error When Subscribing to MQTT Topic in Serverless Framework

Question

I'm experiencing an issue with my Serverless configuration when subscribing to an MQTT topic that triggers a Lambda function. The function is monitored by Sentry, and I'm encountering an error related to SSL/TLS certificates.

Here’s a snippet of my Serverless configuration:

```
functions:
  updateThingStatus:
    handler: src/locations.updateThingStatus
    events:
      - iot:
          sql: "SELECT * FROM '$aws/events/presence/+/+'"
```
I am subscribing to an MQTT topic to invoke my Lambda function, but I am getting the following error:
**unable to get local issuer certificate**
The stack trace from the error is:
```
node:_tls_wrap in TLSSocket.onConnectSecure at line 1674:34
node:events in TLSSocket.emit at line 519:28
node:domain in TLSSocket.emit at line 488:12
node:_tls_wrap in TLSSocket._finishInit at line 1085:8
node:_tls_wrap in ssl.onhandshakedone at line 871:12
node:internal/async_hooks in TLSWrap.callbackTrampoline at line 130:17
```
It seems the error occurs before my Lambda function is called.

Additional Information:
I am using the Serverless Framework to deploy the function.
The Lambda function is monitored using Sentry.

Any insights or suggestions would be greatly appreciated. Thanks!

Hideki_M · Answer

Hi,

I'm not sure what your specific goal is with Lambda, But if you're looking to perform a simple "**ETL**" process, using the **Rule Engine** might be easier than relying on Event-driven Lambda function.

Here is the **Basic IoT Architecture** from [**The IoT Lens of AWS WAF**](https://docs.aws.amazon.com/wellarchitected/latest/iot-lens)

[Edge Layer] -> [Communication Layer: **AWS IoT Core**] -> [Ingestion Layer: **AWS IoT Rules Engine** with **Rules**] -> [Data Processing and Storage: Timestream / S3] <- [Analytics Layer] - [Application Layer: Lambda]

Note:
- Ingestion Layer : AWS IoT Rules Engine, to process and route incoming data

I hope this helps!

"unable to get local issuer certificate" Error When Subscribing to MQTT Topic in Serverless Framework

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