Send emails once AWS Step Functions definition

emails-once-definition.json

{
  "Comment": "Send emails only once",
  "StartAt": "CreateHashFromEmail",
  "States": {
    "CreateHashFromEmail": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "InputPath": "$.email",
      "ResultSelector": {
        "value.$": "$.Payload"
      },
      "Parameters": {
        "Payload.$": "$",
        "FunctionName": "arn:aws:lambda:eu-central-1:000000000000:function:CreateHash:$LATEST"
      },
      "Next": "PutHashInDatabase",
      "ResultPath": "$.hash"
    },
    "PutHashInDatabase": {
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:putItem",
      "InputPath": "$.hash",
      "Parameters": {
        "TableName": "emails",
        "Item": {
          "PK": {
            "S.$": "$.value"
          }
        },
        "ConditionExpression": "attribute_not_exists(PK)"
      },
      "Next": "SendEmail",
      "Catch": [
        {
          "ErrorEquals": [
            "States.TaskFailed"
          ],
          "Next": "IsConditionalCheckFailedException"
        }
      ],
      "ResultPath": null
    },
    "IsConditionalCheckFailedException": {
      "Type": "Choice",
      "Choices": [
        {
          "Variable": "$.Error",
          "StringEquals": "DynamoDB.ConditionalCheckFailedException",
          "Next": "Pass",
          "Comment": "ConditionalCheckFailedException"
        }
      ],
      "Default": "Fail"
    },
    "Pass": {
      "Type": "Pass",
      "End": true
    },
    "Fail": {
      "Type": "Fail"
    },
    "SendEmail": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "OutputPath": "$.Payload",
      "InputPath": "$.email",
      "Parameters": {
        "Payload.$": "$",
        "FunctionName": "arn:aws:lambda:eu-central-1:000000000000:function:SendEmail:$LATEST"
      },
      "End": true
    }
  }
}