trigger lambda function from DynamoDB-CodePudding

Every time a new item arrives in my dynamo table, I want to run a lambda function trigger_lambda_function. This is how I define my table and trigger. However, the trigger does not work as expected.

resource "aws_dynamodb_table" "filenames" {
  name           = local.dynamodb_table_filenames
  billing_mode   = "PROVISIONED"
  read_capacity  = 1000
  write_capacity = 1000
  hash_key       = "filename"

  #range_key      = ""

  attribute {
    name = "filename"
    type = "S"
  }

  tags = var.tags
}


resource "aws_lambda_event_source_mapping" "allow_dynamodb_table_to_trigger_lambda" {
  event_source_arn  = aws_dynamodb_table.filenames.stream_arn
  function_name     = aws_lambda_function.trigger_stepfunction_lambda.arn
  starting_position = "LATEST"
}

Upon terraform apply, I get an error that:

│ Error: error creating Lambda Event Source Mapping (): InvalidParameterValueException: Unrecognized event source.
│ {
│   RespMetadata: {
│     StatusCode: 400,
│     RequestID: "5ae68da6-3f6d-4adb-b104-72ae584dbca7"
│   },
│   Message_: "Unrecognized event source.",
│   Type: "User"
│ }
│ 
│   with module.ingest_system["alpegatm"].aws_lambda_event_source_mapping.allow_dynamodb_table_to_trigger_lambda,
│   on ../../modules/ingest_system/dynamo.tf line 39, in resource "aws_lambda_event_source_mapping" "allow_dynamodb_table_to_trigger_lambda":
│   39: resource "aws_lambda_event_source_mapping" "allow_dynamodb_table_to_trigger_lambda" {

I also tried .arn instead of stream_arnbut that threw an error too. What else could I try?

I followed the documentation for the trigger: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/lambda_event_source_mapping

CodePudding user response：

From the aws_dynamodb_table docs, stream_arn is only available if stream_enabled is set to true. You might want to add stream_enabled = true to your DynamoDB table definition.

By default stream_enabled is set to false. You can see all the default values here for aws_dynamodb_table.