Help! Serverless offline failing to start with serverless-offline-sns

Question

Hello!

I am getting this error trying to run serverless offline:

> Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/home/mypc/Downloads/textai/src/functions/processExpenseAnalysisJob.js' imported from /home/mypc/Downloads/textai/node_modules/serverless-offline-sns/dist/index.js

I was trying to add serverless-offline-sns to work in local, but I can't seem to start the app if I put it in plugins, if I remove it, it works. I already deleted node_modules and a npm install. Do I need to use something additional like working with serverless-offline-sqs which I needed elastiqmq?  I am using SNS with from:

```
    const command = new StartExpenseAnalysisCommand({
      DocumentLocation: {
        S3Object: {
          Bucket: fileObj.s3.bucket.name,
          Name: fileObj.s3.object.key,
        },
      },
      NotificationChannel: {
        SNSTopicArn: process.env.SNS_TOPIC_ARN,
        RoleArn: process.env.ROLE_ARN,
      },
    });
```

Which will trigger processExpenseAnalysisJob handler, before I was testing deploying and it works there perfectly.

My serverless.yml
```
service: ${env:APP_SERVICE_NAME}
useDotenv: true
configValidationMode: warn

plugins:
  - serverless-offline-sqs
  - serverless-offline-sns
  - serverless-offline
  - serverless-plugin-typescript
  - serverless-plugin-optimize

provider:
  name: aws
  runtime: nodejs18.x
  memorySize: 128
  region: ${env:AWS_REGION}
  stage: ${opt:stage,'dev'}
  environment:
    # APP
    APP_STAGE: ${env:APP_STAGE}
    APP_SERVICE_NAME: ${env:APP_SERVICE_NAME}
    AWS_ACCOUNT_ID: ${env:AWS_ACCOUNT_ID}
    DEVELOPMENT_PATH: ${env:DEVELOPMENT_PATH}
    EXCHANGE_RATE_API: ${env:EXCHANGE_RATE_API}
    SNS_TOPIC_ARN: !GetAtt TextractTriggerTopic.TopicArn
    ROLE_ARN: ${env:ROLE_ARN}

iam:
    role:
      statements:
        - Effect: Allow
          Action:
            - sqs:SendMessage
            - sqs:ReceiveMessage
            - sqs:DeleteMessage
          Resource: !GetAtt MySQSQueue.Arn
        - Effect: Allow
          Action:
            - textract:StartExpenseAnalysis
            - textract:GetExpenseAnalysis
          Resource: "*"
        - Effect: Allow
          Action:
            - s3:GetObject
            - s3:PutObject
          Resource: "*"
        - Effect: Allow
          Action:
            - sns:Publish
          Resource: !GetAtt TextractTriggerTopic.TopicArn
        - Effect: Allow
          Action:
            - lambda:InvokeFunction
          Resource: "*"

functions:
  startExpenseAnalysisJob:
    handler: src/functions/startExpenseAnalysisJob.handler
    timeout: 180
    maximumRetryAttempts: 1
    events:
      - sqs:
          arn: !GetAtt MySQSQueue.Arn
  processExpenseAnalysisJob:
    handler: src/functions/processExpenseAnalysisJob.handler
    events:
      - sns:
          arn: !GetAtt TextractTriggerTopic.TopicArn
          topicName: TextractTriggerTopic-${self:provider.stage}

resources:
  Resources:
    MySQSQueue:
      Type: AWS::SQS::Queue
      Properties:
        QueueName: TextractTriggerQueue-${self:provider.stage}
        VisibilityTimeout: 360

TextractTriggerTopic:
      Type: AWS::SNS::Topic
      Properties:
        TopicName: TextractTriggerTopic

custom:
  serverless-offline-sqs:
    autoCreate: true
    apiVersion: "2012-11-05"
    endpoint: http://0.0.0.0:9324
    region: ${self:provider.region}
    accessKeyId: root
    secretAccessKey: root
    skipCacheInvalidation: false

serverless-offline-sns:
    port: 4002
    debug: false
    host: 0.0.0.0
    endpoint: http://localhost:4001

```

And this is my package.json

```
  "devDependencies": {
    "@types/aws-lambda": "^8.10.134",
    "dotenv": "^16.4.5",
    "prettier": "^3.2.5",
    "serverless": "^3.38.0",
    "serverless-offline": "^13.3.3",
    "serverless-offline-sns": "^0.77.2",
    "serverless-offline-sqs": "^8.0.0",
    "serverless-plugin-optimize": "^4.2.1-rc.1",
    "serverless-plugin-typescript": "^2.1.5",
    "ts-node": "^10.9.2",
    "typescript": "^5.3.3"
  },
  "dependencies": {
    "@aws-sdk/client-s3": "^3.525.0",
    "@aws-sdk/client-sqs": "^3.525.0",
    "@aws-sdk/client-textract": "^3.525.0",
    "amazon-textract-response-parser": "^0.4.0",
    "axios": "^1.6.7"
  }
```

Accepted Answer

I found the solution for anyone wondering...

The error was the order for my serverless.yml plugins, which should be the following:

```
plugins:
  - serverless-plugin-typescript  # Must be before transpilation plugins
  - serverless-plugin-optimize    # Can be before or after transpilation
  - serverless-offline-sns       # Can be in any order
  - serverless-offline-sqs       # Can be in any order
  - serverless-offline           # Must be last
```

*  serverless-plugin-typescript: This plugin transpiles your TypeScript code to JavaScript. It needs to be placed before any plugins that modify the JavaScript code, thats why I was getting Error [ERR_MODULE_NOT_FOUND] as I had issue with my ts files, as serverless-offline plugin cannot find equivalent js file it throws error module not found as stated here serverless-plugin-typescript.
*  serverless-offline: This plugin requires all the other plugins to be loaded first, so it should be placed last.

Following this order ensures that the plugins are executed in the correct sequence to achieve the desired outcome: transpiling TypeScript, potentially optimizing the code, and then setting up the offline environment.

Answer

Is there anyone that knows?  I can't seem to find the problem.  But the part that gives me that error is this section of my serverless.yml:

```
functions:
  ......
  processExpenseAnalysisJob:
    handler: src/functions/processExpenseAnalysisJob.handler
    events:
      - sns:
          arn: arn:aws:sns:${self:provider.region}:${aws:accountId}:TextractTriggerTopic
  .....
```
When I add the sns event to my lambda function, if I remove the event it works, but I can't seem to find what's wrong following this: https://www.serverless.com/plugins/serverless-offline-sns#configure. Before I had `!GetAtt TextractTriggerTopic.TopicArn` but changed it as serverless-offline-sns doesn't recognize !GetAtt when running serverless offline.

Help! Serverless offline failing to start with serverless-offline-sns

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