使用为Step Functions 创建 Lambda 状态机Amazon CloudFormation - Amazon Step Functions
Amazon Web Services 文档中描述的 Amazon Web Services 服务或功能可能因区域而异。要查看适用于中国区域的差异,请参阅中国的 Amazon Web Services 服务入门

本文属于机器翻译版本。若本译文内容与英语原文存在差异,则一律以英文原文为准。

使用为Step Functions 创建 Lambda 状态机Amazon CloudFormation

本教程向您展示如何使用 Amazon CloudFormation 创建基本 Amazon Lambda 函数。您将使用Amazon CloudFormation控制台和 YAML 模板来创建堆栈(IAM 角色、Lambda 函数和状态机)。然后,你将使用Amazon Step Functions控制台开始执行状态机。

有关更多信息,请参阅使用 CloudFormation 模板Amazon CloudFormation用户指南中的AWS::StepFunctions::StateMachine资源。

步骤 1:设置您的Amazon CloudFormation模板

在使用示例模板之前,您应该了解如何声明 Amazon CloudFormation 模板的不同部分。

为 Lambda 创建 IAM 角色

定义与 Lambda 函数的 IAM 角色关联的信任策略。以下示例使用 YAML 或 JSON 定义信任策略。

YAML
LambdaExecutionRole: Type: "AWS::IAM::Role" Properties: AssumeRolePolicyDocument: Version: "2012-10-17" Statement: - Effect: Allow Principal: Service: lambda.amazonaws.com Action: "sts:AssumeRole"
JSON
"LambdaExecutionRole": { "Type": "AWS::IAM::Role", "Properties": { "AssumeRolePolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": { "Service": "lambda.amazonaws.com" }, "Action": "sts:AssumeRole" } ] } }

创建 Lambda 函数

为将打印消息的 Lambda 函数定义以下属性Hello World

重要

确保您的 Lambda 函数与状态机位于相同的Amazon账户和Amazon区域下。

YAML
MyLambdaFunction: Type: "AWS::Lambda::Function" Properties: Handler: "index.handler" Role: !GetAtt [ LambdaExecutionRole, Arn ] Code: ZipFile: | exports.handler = (event, context, callback) => { callback(null, "Hello World!"); }; Runtime: "nodejs12.x" Timeout: "25"
JSON
"MyLambdaFunction": { "Type": "AWS::Lambda::Function", "Properties": { "Handler": "index.handler", "Role": { "Fn::GetAtt": [ "LambdaExecutionRole", "Arn" ] }, "Code": { "ZipFile": "exports.handler = (event, context, callback) => {\n callback(null, \"Hello World!\");\n};\n" }, "Runtime": "nodejs12.x", "Timeout": "25" } },

为状态机执行创建 IAM 角色

定义与状态机执行的 IAM 角色关联的信任策略。

YAML
StatesExecutionRole: Type: "AWS::IAM::Role" Properties: AssumeRolePolicyDocument: Version: "2012-10-17" Statement: - Effect: "Allow" Principal: Service: - !Sub states.${AWS::Region}.amazonaws.com Action: "sts:AssumeRole" Path: "/" Policies: - PolicyName: StatesExecutionPolicy PolicyDocument: Version: "2012-10-17" Statement: - Effect: Allow Action: - "lambda:InvokeFunction" Resource: "*"
JSON
"StatesExecutionRole": { "Type": "AWS::IAM::Role", "Properties": { "AssumeRolePolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": { "Service": [ { "Fn::Sub": "states.${AWS::Region}.amazonaws.com" } ] }, "Action": "sts:AssumeRole" } ] }, "Path": "/", "Policies": [ { "PolicyName": "StatesExecutionPolicy", "PolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "lambda:InvokeFunction" ], "Resource": "*" } ] } } ] } },

创建 Lambda 状态机

定义 Lambda 状态机。

YAML
MyStateMachine: Type: "AWS::StepFunctions::StateMachine" Properties: DefinitionString: !Sub - |- { "Comment": "A Hello World example using an Amazon Lambda function", "StartAt": "HelloWorld", "States": { "HelloWorld": { "Type": "Task", "Resource": "${lambdaArn}", "End": true } } } - {lambdaArn: !GetAtt [ MyLambdaFunction, Arn ]} RoleArn: !GetAtt [ StatesExecutionRole, Arn ]
JSON
"MyStateMachine": { "Type": "AWS::StepFunctions::StateMachine", "Properties": { "DefinitionString": { "Fn::Sub": [ "{\n \"Comment\": \"A Hello World example using an AWS Lambda function\",\n \"StartAt\": \"HelloWorld\",\n \"States\": {\n \"HelloWorld\": {\n \"Type\": \"Task\",\n \"Resource\": \"${lambdaArn}\",\n \"End\": true\n }\n }\n}", { "lambdaArn": { "Fn::GetAtt": [ "MyLambdaFunction", "Arn" ] } } ] }, "RoleArn": { "Fn::GetAtt": [ "StatesExecutionRole", "Arn" ] } } }

步骤 2:使用Amazon CloudFormation模板创建 Lambda 状态机

了解了Amazon CloudFormation模板的组成部分后,就可以将它们组合在一起并使用该模板创建Amazon CloudFormation堆栈。

创建 Lambda 状态机

  1. 将以下示例数据复制到名为 MyStateMachine.yaml(适用于 YAML 示例)或 MyStateMachine.json(适用于 JSON)的文件中。

    YAML
    AWSTemplateFormatVersion: "2010-09-09" Description: "An example template with an IAM role for a Lambda state machine." Resources: LambdaExecutionRole: Type: "AWS::IAM::Role" Properties: AssumeRolePolicyDocument: Version: "2012-10-17" Statement: - Effect: Allow Principal: Service: lambda.amazonaws.com Action: "sts:AssumeRole" MyLambdaFunction: Type: "AWS::Lambda::Function" Properties: Handler: "index.handler" Role: !GetAtt [ LambdaExecutionRole, Arn ] Code: ZipFile: | exports.handler = (event, context, callback) => { callback(null, "Hello World!"); }; Runtime: "nodejs12.x" Timeout: "25" StatesExecutionRole: Type: "AWS::IAM::Role" Properties: AssumeRolePolicyDocument: Version: "2012-10-17" Statement: - Effect: "Allow" Principal: Service: - !Sub states.${AWS::Region}.amazonaws.com Action: "sts:AssumeRole" Path: "/" Policies: - PolicyName: StatesExecutionPolicy PolicyDocument: Version: "2012-10-17" Statement: - Effect: Allow Action: - "lambda:InvokeFunction" Resource: "*" MyStateMachine: Type: "AWS::StepFunctions::StateMachine" Properties: DefinitionString: !Sub - |- { "Comment": "A Hello World example using an Amazon Lambda function", "StartAt": "HelloWorld", "States": { "HelloWorld": { "Type": "Task", "Resource": "${lambdaArn}", "End": true } } } - {lambdaArn: !GetAtt [ MyLambdaFunction, Arn ]} RoleArn: !GetAtt [ StatesExecutionRole, Arn ]
    JSON
    { "AWSTemplateFormatVersion": "2010-09-09", "Description": "An example template with an IAM role for a Lambda state machine.", "Resources": { "LambdaExecutionRole": { "Type": "AWS::IAM::Role", "Properties": { "AssumeRolePolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": { "Service": "lambda.amazonaws.com" }, "Action": "sts:AssumeRole" } ] } } }, "MyLambdaFunction": { "Type": "AWS::Lambda::Function", "Properties": { "Handler": "index.handler", "Role": { "Fn::GetAtt": [ "LambdaExecutionRole", "Arn" ] }, "Code": { "ZipFile": "exports.handler = (event, context, callback) => {\n callback(null, \"Hello World!\");\n};\n" }, "Runtime": "nodejs12.x", "Timeout": "25" } }, "StatesExecutionRole": { "Type": "AWS::IAM::Role", "Properties": { "AssumeRolePolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": { "Service": [ { "Fn::Sub": "states.${AWS::Region}.amazonaws.com" } ] }, "Action": "sts:AssumeRole" } ] }, "Path": "/", "Policies": [ { "PolicyName": "StatesExecutionPolicy", "PolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "lambda:InvokeFunction" ], "Resource": "*" } ] } } ] } }, "MyStateMachine": { "Type": "AWS::StepFunctions::StateMachine", "Properties": { "DefinitionString": { "Fn::Sub": [ "{\n \"Comment\": \"A Hello World example using an AWS Lambda function\",\n \"StartAt\": \"HelloWorld\",\n \"States\": {\n \"HelloWorld\": {\n \"Type\": \"Task\",\n \"Resource\": \"${lambdaArn}\",\n \"End\": true\n }\n }\n}", { "lambdaArn": { "Fn::GetAtt": [ "MyLambdaFunction", "Arn" ] } } ] }, "RoleArn": { "Fn::GetAtt": [ "StatesExecutionRole", "Arn" ] } } } } }
  2. 打开 Amazon CloudFormation 控制台并选择创建堆栈

  3. Select Template (选择模板) 页面上,选择 Upload a template to Amazon S3 (将模板上传到 Amazon S3)。选择您的 MyStateMachine 文件,然后选择 Next

  4. 指定详细信息页面上,为堆栈名称输入 MyStateMachine,然后选择下一步

  5. Options (选项) 页面上,选择 Next (下一步)

  6. 审核页面上,选择我确认这Amazon CloudFormation可能会创建 IAM 资源。 然后选择 “创建”。

    Amazon CloudFormation 开始创建 MyStateMachine 堆栈,并显示 CREATE_IN_PROGRESS 状态。在此过程完成后,Amazon CloudFormation 将显示 CREATE_COMPLETE 状态。

  7. (可选) 要显示您的堆栈中的资源,请选择堆栈,然后选择 Resources 选项卡。

    
                显示资源

步骤 3:开始执行状态机

在创建您的 Lambda 状态机后,您就可以开始执行。

启动状态机执行

  1. 打开 Step Functions 控制台并选择您使用创建的状态机的名称Amazon CloudFormation。

  2. MyStateMachine-ABCDEFGHIJ1K 页面上,选择 “新建执行”。

    此时将显示 New execution 页面。

  3. (可选)要识别您的执行情况,可以在 “名称” 框中为其指定名称。默认情况下,Step Functions 会自动生成唯一的执行名称。

    注意

    Step Functions 允许您创建包含非 ASCII 字符的状态机、执行和活动名称。这些非 ASCII 名称不适用于亚马逊 CloudWatch。为确保您可以跟踪 CloudWatch 指标,请选择仅使用 ASCII 字符的名称。

  4. 选择 Start Execution (开始执行)

    此时将启动新的状态机执行,并显示一个说明正在运行的执行的新页面。

  5. (可选)在 Execution Details (执行详细信息) 中,查看 Execution Status (执行状态) 以及 Started (已开始)Closed (已关闭) 时间戳。

  6. 要查看执行结果,请选择 Output