amazon-web-services - 内联 Lambda CFT "Fn::Join"错误 - JSON

Question

我正在编写一个 JSON 格式的云形成模板。该模板具有一个类型为 FSx 文件系统 ID 的 CommaDelimitedList 的参数和一个 Lambda 函数资源，该资源引用 FSx 文件系统 ID 的参数并检查其状态。我正在模板中内联编写此 Lambda 函数。

我收到以下错误:

Template error: every Fn::Join object requires two parameters, (1) a string delimiter and (2) a list of strings to be joined or a function that returns a list of strings (such as Fn::GetAZs) to be joined.

这是我的模板:

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Parameters": {
    "FSIds": {
      "Type": "CommaDelimitedList",
      "Description": "Enter the file system IDs separated by commas"
    }
  },
  "Resources": {
    "FSxStatusLambdaFunction": {
      "Type": "AWS::Lambda::Function",
      "Properties": {
        "FunctionName": "test-FSx",
        "Architectures": [ "x86_64" ],
        "Description": "Lambda function that checks FSx file systems status and sends notification",
        "Handler": "index.handler",
        "Code": {
          "ZipFile": {
            "Fn::Join": [
              "\n",
              [
                  "import boto3",
                  "fsx = boto3.client('fsx')",
                  "#Publish message to SNS topic",
                  "def publish_message(FS_ID , status):",
                  "    sns = boto3.client('sns')",
                  "    topic = \"arn:aws:sns:us-east-1:123456789:FSx-Notification\"",
                  "    msg = \"{FS_ID} is in {status} state\".format(FS_ID=FS_ID , status=status)",
                  "    response = sns.publish(",
                  "        TopicArn = topic,",
                  "        Message = msg",
                  "        )",
                  "#Lambda handler function",
                  "def lambda_handler(event, context):",
                  "    res = fsx.describe_file_systems(",
                  "        FileSystemIds = ",
                  {
                    "Ref": "FSIds"
                  },
                  "        )",
                  "    for i in range(len(res[\"FileSystems\"])):",
                  "        FS_ID = res[\"FileSystems\"][i][\"FileSystemId\"]",
                  "        status = res[\"FileSystems\"][i][\"Lifecycle\"]",
                  "        if status == \"MISCONFIGURED\" or status == \"FAILED\":",
                  "            publish_message(FS_ID , status)",
              ]
            ]
          }
        },
        "Role": "arn:aws:iam::123456789:role/FSx-LambdaRole",
        "Runtime": "python3.9",
        "Timeout": "60",
        "Tags": [
          {
            "Key": "Owner",
            "Value": "God"
          }
        ]
      }
    }
  }
}

在创建堆栈时，我将参数的输入指定为:fs-123,fs-456

请帮忙!!

Answer 1

该错误是由参数的 CommaDelimitedList 类型间接引起的。它导致 FSIds 成为列表/数组而不是字符串，这意味着 Fn::Join 字符串列表中的此项不是字符串:

    {
        "Ref": "FSIds"
    },

如果您将参数类型更改为String，它将为您创建堆栈。

或者，您可以保留 CommaDelimitedList 并将上面的内容更改为:

    {
        "Fn::Join": [ ",", { "Ref": "FSIds" } ]
    },

其中任何一个至少都会让您克服当前遇到的错误。

更新:

正如您所指出的，FileSystemIds 实际上需要是一个列表，因此您有几个选项:

1. 更改 CF 模板，虽然很痛苦，但可以做到。像这样的东西(未经测试):

                {
                  "Fn::Join": [
                    "",
                    [
                      "        FileSystemIds = [\"",
                      {
                        "Fn::Join": [
                          "\", \"",
                          {
                            "Ref": "FSIds"
                          }
                        ]
                      },
                      "\""
                    ]
                  ]
                },

类似，但让 Python 使用 str.split() 完成一些工作，例如像这样(请注意，这两者都假设 FSIds 仍然是 CommaDelimitedList):

                  {
                      "Fn::Join": [
                          "",
                          [
                              "        FileSystemIds = str.split(\"",
                              { "Fn::Join": [ ",", { "Ref": "FSIds" } ] },
                              "\", \",\")"
                          ]
                      },
                  },

以不同的方式传递参数，不涉及通过 CF 编写精确的 Python 代码，例如 Lambda 的环境变量:https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-lambda-function-environment.html