如何在 AWS Step Functions 中的 Lambda 函数之间传递参数

Question

我试图浏览互联网，但在 python 中似乎没有一个解决方案对我有用。 Basicly I want to transfer some parameters from one lambda function to the next lambda function in a step function. 我有点惊讶要找到一个简单的例子来说明如何做到这一点有多么困难？

所以我的第一个 lambda function 有一个 output 像：

return {"user_name" : user_name, "region" : region, "instance_id" : instance_id}

我的第二个 lambda function 尝试导入：

user_name = event["user_name"]
region = event["region"]
instance_id = event["instance_id"]

我的 stepfunction 看起来像：

{
         "StartAt": "CreateEC2Instance",
         "States": {
           "CreateEC2Instance": {
             "Type": "Task",
             "Resource": "arn:aws:states:::lambda:invoke",
             "Parameters": {
               "FunctionName": "MY_ARN_1",
               "Payload": {
                  "region": "eu-central-1",
                  "user_name": "MY_USERNAME"
              }},
             "Next": "AttachEFStoEC2"
           },
            "AttachEFStoEC2": {
             "Type": "Task",
             "Resource":"MY_ARN_2",
             "End": true
         }

错误是：

{
  "error": "KeyError",
  "cause": {
    "errorMessage": "'user_name'",
    "errorType": "KeyError",
    "stackTrace": [
      "  File \"/var/task/lambda_function.py\", line 7, in lambda_handler\n    user_name = event[\"user_name\"]\n"
    ]
  }
}

Answer 1

{
         "StartAt": "CreateEC2Instance",
         "States": {
           "CreateEC2Instance": {
             "Type": "Task",
             "Resource": "arn:aws:states:::lambda:invoke",
             "ResultPath": "$.randomstring",
             "Parameters": {
               "FunctionName": "MY_ARN_1",
               "Payload": {
                  "region": "eu-central-1",
                  "user_name": "MY_USERNAME"
              }},
             "Next": "AttachEFStoEC2"
           },
            "AttachEFStoEC2": {
             "Type": "Task",
             "Resource":"MY_ARN_2",
                   "Parameters": {
                       "outputfromearlierfunction.$": "$.randomstring.Payload"
                   },
             "End": true
         }

然后尝试访问 function 之类的内部

receivedinput = event.get('outputfromearlierfunction')
user_name = receivedinput["user_name"]
region = receivedinput["region"]
instance_id = receivedinput["instance_id"]