我可以在状态机定义文件中使用全局变量吗？

Question

我正在使用 AWS SAM 开发一个无服务器项目，该项目由 lambda 和状态机资源组成（请参阅下面的 SAM 模板）。我想知道是否有一种方法可以在我的状态机定义文件中定义一个“全局”变量，就像我们可以将Globals 用于 SAM 模板一样。

我想这样做的原因是为了缩短我的状态机定义。现在有状态使用完全相同的属性，例如我的 Fargate 任务的 NetworkConfiguration 块：

definition.asl.json

{
    "StartAt": "Generate Config",
    "States": {
        "Generate Config": {
            "Type": "Task",
            "Resource": "${GenerateConfigFunctionArn}",
            "Next": "ETL"
        },
        "ETL": {
            "Type": "Task",
            "Resource": "arn:aws:states:::ecs:runTask.sync",
            "Next": "ETL",
            "Parameters": {
                "LaunchType": "FARGATE",
                "Cluster": "arn:aws:ecs:region:11111111:cluster/clustername",
                "TaskDefinition": "arn:aws:ecs:region:11111111:task-definition/taskdef",
                "NetworkConfiguration": {
                    "AwsvpcConfiguration": {
                        "Subnets": [
                            "subnet-00d610225d369486e"
                        ],
                        "SecurityGroups": [
                            "sg-016650ff9ecd28a9a"
                        ],
                        "AssignPublicIp": "ENABLED"
                    }
                },
                "Overrides": {
                    "ContainerOverrides": [
                        {
                            "Name": "Phase-1-start",
                            "Environment": [
                                {
                                    "Name": "COMMAND",
                                    "Value": "etl"
                                }
                            ]
                        }
                    ]
                }
            }
        },
        "Well_Calc": {
            "Type": "Task",
            "Resource": "arn:aws:states:::ecs:runTask.sync",
            "End": true,
            "Parameters": {
                "LaunchType": "FARGATE",
                "Cluster": "arn:aws:ecs:region:11111111:cluster/clustername",
                "TaskDefinition": "arn:aws:ecs:region:11111111:task-definition/taskdef",
                "NetworkConfiguration": {
                    "AwsvpcConfiguration": {
                        "Subnets": [
                            "subnet-00d610225d369486e"
                        ],
                        "SecurityGroups": [
                            "sg-016650ff9ecd28a9a"
                        ],
                        "AssignPublicIp": "ENABLED"
                    }
                },
                "Overrides": {
                    "ContainerOverrides": [
                        {
                            "Name": "Phase-1-start",
                            "Environment": [
                                {
                                    "Name": "COMMAND",
                                    "Value": "calculation"
                                }
                            ]
                        }
                    ]
                }
            }
        }
    }
}

SAM template

AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31

Resources:
  MySAMPOC:
    Type: AWS::Serverless::StateMachine
    Properties:
      DefinitionUri: stateMachine/definition.asl.json
      DefinitionSubstitutions:
        GenerateConfigFunctionArn: !GetAtt GenerateConfigFunction.Arn
  GenerateConfigFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: functions/generate_config
      Handler: app.lambda_handler
      Runtime: python3.8

状态机定义是否支持使用 Globals（或类似的）？

Answer 1

目前不支持 AWS::Serverless::StateMachine 的全局变量。您可以考虑一些替代方案：

• 将DefinitionSubstitutions 用于某些值：https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-resource-statemachine.html#sam-statemachine-definitionsubstitutions
• Step Function 现在在开发工具中支持 YAML，因此从 JSON 切换到 YAML 至少会节省一些缩进和大括号。 https://aws.amazon.com/about-aws/whats-new/2021/03/aws-step-functions-adds-tooling-support-for-yaml/
• 使用 CDK 定义您的状态机。您可以创建封装公共属性的自定义构造。显然这不是 SAM，但您可以将 SAM 资源与 CDK 应用程序集成，或者考虑将应用程序的一部分迁移到 CDK。 https://docs.aws.amazon.com/cdk/api/latest/docs/aws-stepfunctions-readme.html