feat: Add support for error action on IoT topic rule by cyphercodes · Pull Request #13423 · serverless/serverless · GitHub

Description

This PR adds support for error action configuration on AWS IoT topic rules. This allows users to specify a Lambda function that will be invoked when the IoT rule fails to execute.

Closes #11642

Changes

Added errorAction property to the IoT event schema
Added support for errorAction.lambda.functionArn to specify the error handling Lambda function
Added unit test for the new functionality

Usage Example

functions:
  myFunction:
    handler: handler.main
    events:
      - iot:
          sql: "SELECT * FROM 'my/topic'"
          errorAction:
            lambda:
              functionArn: arn:aws:lambda:us-east-1:123456789012:function:errorHandler

Summary by CodeRabbit

New Features
- Support for configuring IoT rule error actions: specify a Lambda function ARN to handle rule failures; compiled deployment includes the necessary permission for IoT to invoke that Lambda.
Tests
- Added unit tests to validate error-action configuration and correct CloudFormation compilation (including the error-action invocation permission).

- Add errorAction property to IoT event schema - Handle errorAction.lambda.functionArn in compileIoTEvents - Add unit test for errorAction functionality Fixes serverless#11642

✅ Snyk checks have passed. No issues have been found so far.

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✅	Code Security	0	0	0	0	0 issues

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ℹ️ Recent review info ⚙️ Run configuration

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Review profile: CHILL

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Run ID: 445e0e24-920c-4f8a-88f3-58c9abac9d25

📥 Commits

Reviewing files that changed from the base of the PR and between 53c73fc and 902f707.

📒 Files selected for processing (2)

packages/serverless/lib/plugins/aws/package/compile/events/iot.js
packages/serverless/test/unit/lib/plugins/aws/package/compile/events/iot.test.js

🚧 Files skipped from review as they are similar to previous changes (2)

packages/serverless/test/unit/lib/plugins/aws/package/compile/events/iot.test.js
packages/serverless/lib/plugins/aws/package/compile/events/iot.js

📝 Walkthrough

Walkthrough

Added optional errorAction support to AWS IoT event schema and CloudFormation compilation: when event.iot.errorAction.lambda.functionArn is provided, the TopicRulePayload includes ErrorAction.Lambda.FunctionArn and an accompanying AWS::Lambda::Permission resource is generated.

Changes

Cohort / File(s)	Summary
IoT Event Schema & Compilation packages/serverless/lib/plugins/aws/package/compile/events/iot.js	Added errorAction schema (errorAction.lambda.functionArn) and updated TopicRulePayload compilation to include ErrorAction when configured. Also generates a separate AWS::Lambda::Permission resource for the error-action Lambda.
IoT Event Unit Tests packages/serverless/test/unit/lib/plugins/aws/package/compile/events/iot.test.js	Added test asserting TopicRule payload contains ErrorAction: { Lambda: { FunctionArn } } and that a corresponding AWS::Lambda::Permission resource (with iot.amazonaws.com principal and correct FunctionName) is created.

Sequence Diagram(s)

sequenceDiagram
  participant Dev as Developer / serverless.yml
  participant SLS as Serverless Compile Plugin
  participant CF as CloudFormation Template
  participant IoT as AWS::IoT::TopicRule
  participant Lambda as AWS::Lambda::Permission / Function

  Dev->>SLS: define iot event with errorAction.lambda.functionArn
  SLS->>CF: compile TopicRulePayload (include ErrorAction when present)
  SLS->>CF: add AWS::Lambda::Permission resource for errorAction Lambda
  CF->>IoT: create TopicRule with ErrorAction -> Lambda.FunctionArn
  CF->>Lambda: attach permission allowing iot.amazonaws.com to invoke function

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I nibbled code by moonlit beam,
ErrorAction stitched into the stream.
If IoT rules take a tumble,
A Lambda saves the humble.
Hops of joy — CI's green gleam! 🥕✨

🚥 Pre-merge checks | ✅ 5 ✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding support for error action on IoT topic rules, which aligns with the changeset.
Linked Issues check	✅ Passed	The PR successfully implements all coding requirements from issue #11642: errorAction schema property, Lambda ARN support, CloudFormation template generation with ErrorAction, and Lambda::Permission creation for error-handling.
Out of Scope Changes check	✅ Passed	All changes are directly within scope: schema extension for errorAction, CloudFormation compilation logic, Lambda permission generation, and corresponding unit tests. No unrelated modifications detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/serverless/lib/plugins/aws/package/compile/events/iot.js`:
- Around line 43-62: The errorAction schema currently allows an empty object
because it doesn't require any action types; update the errorAction schema (the
errorAction object and its properties) to require at least one action type by
adding required: ['lambda'] under the errorAction definition (so that when
errorAction is present it must include the lambda property), and keep
additionalProperties: false; alternatively, if you intend to support multiple
action types in future, replace the properties + required approach with a oneOf
pattern similar to the redrivePolicy/sns pattern so at least one action variant
is enforced.
- Around line 136-143: The template currently always creates
TopicRulePayload.ErrorAction (event.iot.errorAction) even when no lambda is
configured and it never creates a corresponding AWS::Lambda::Permission for an
error-action lambda; update the logic in the compile step that builds
topicRuleResource (symbols: event.iot.errorAction,
topicRuleResource.Properties.TopicRulePayload.ErrorAction) so that ErrorAction
is only set when event.iot.errorAction.lambda exists, and when you detect an
error-action lambda generate a matching permission resource (same pattern used
for the main action's AWS::Lambda::Permission resource) granting
iot.amazonaws.com invoke rights to that lambda ARN (or alternatively add a
schema warning if you cannot create a static/resolvable ARN); ensure the
permission resource uses a unique logical ID analogous to the existing
permission resource generation code.

ℹ️ Review info ⚙️ Run configuration

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Run ID: 9d1c6359-7a86-47a3-8f5f-86d07adb1045

📥 Commits

Reviewing files that changed from the base of the PR and between 8905d7a and 53c73fc.

⛔ Files ignored due to path filters (1)

package-lock.json is excluded by !**/package-lock.json

📒 Files selected for processing (2)

packages/serverless/lib/plugins/aws/package/compile/events/iot.js
packages/serverless/test/unit/lib/plugins/aws/package/compile/events/iot.test.js

- Add required: ['lambda'] to errorAction schema to prevent empty objects - Only create ErrorAction when event.iot.errorAction.lambda exists - Generate AWS::Lambda::Permission for error-action lambda - Update tests to verify error action Lambda permission creation

feat: Add support for error action on IoT topic rule

53c73fc

- Add errorAction property to IoT event schema - Handle errorAction.lambda.functionArn in compileIoTEvents - Add unit test for errorAction functionality Fixes serverless#11642

coderabbitai Bot reviewed Mar 25, 2026

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Comment thread packages/serverless/lib/plugins/aws/package/compile/events/iot.js

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feat: Add support for error action on IoT topic rule by cyphercodes · Pull Request #13423 · serverless/serverless · GitHub

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feat: Add support for error action on IoT topic rule - #13423

feat: Add support for error action on IoT topic rule#13423
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feat: Add support for error action on IoT topic rule by cyphercodes · Pull Request #13423 · serverless/serverless · GitHub

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feat: Add support for error action on IoT topic rule - #13423

feat: Add support for error action on IoT topic rule#13423cyphercodes wants to merge 2 commits intoserverless:mainserverless/serverless:mainfrom cyphercodes:feat/iot-error-actioncyphercodes/serverless:feat/iot-error-actionCopy head branch name to clipboard

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Description

Changes

Usage Example

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Walkthrough

Changes

Sequence Diagram(s)

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feat: Add support for error action on IoT topic rule#13423
cyphercodes wants to merge 2 commits into
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cyphercodes:feat/iot-error-action

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