AWS Step Functions
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使用 AWS CloudFormation 创建 Lambda 状态机

本教程向您展示如何使用 AWS CloudFormation 创建基本 AWS Lambda 函数。您将使用 AWS 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,您将使用 AWS Step Functions 控制台启动状态机执行。

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

步骤 1:设置您的 AWS CloudFormation 模板

使用示例模板之前,您应该了解其各个部分。

创建用于 Lambda 的 IAM 角色

定义与 Lambda 函数的 IAM 角色关联的信任策略。

YAMLJSON
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

定义输出消息 Hello World 的 Lambda 函数的以下属性。

重要

确保您的 Lambda 函数与状态机位于同一 AWS 账户和 AWS 区域下。

YAMLJSON
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: "nodejs8.10" 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": "nodejs8.10", "Timeout": "25" } },

创建用于状态机执行的 IAM 角色

定义与状态机执行的 IAM 角色关联的信任策略。

YAMLJSON
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。

YAMLJSON
YAML
MyStateMachine: Type: "AWS::StepFunctions::StateMachine" Properties: DefinitionString: !Sub - |- { "Comment": "A Hello World example using an AWS 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 AWS CloudFormation 模板创建 Lambda 状态机

在您了解 AWS CloudFormation 模板的各个部分后,可以将这些部分放在一起,并使用模板创建 AWS 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。

    YAMLJSON
    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: "nodejs8.10" Timeout: "25" StatesExecutionRole: Type: "AWS::IAM::Role" Properties: AssumeRolePolicyDocument: Version: "2012-10-17" Statement: - Effect: "Allow" Principal: Service: - !Sub states.${AWS::Region}.amazonaws.com Action: "sts:AssumeRole" Path: "/" Policies: - PolicyName: StatesExecutionPolicy PolicyDocument: Version: "2012-10-17" Statement: - Effect: Allow Action: - "lambda:InvokeFunction" Resource: "*" MyStateMachine: Type: "AWS::StepFunctions::StateMachine" Properties: DefinitionString: !Sub - |- { "Comment": "A Hello World example using an AWS Lambda function", "StartAt": "HelloWorld", "States": { "HelloWorld": { "Type": "Task", "Resource": "${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": "nodejs8.10", "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 AWS CloudFormation 控制台并选择创建堆栈

  3. Select Template 页面上,选择 Upload a template to 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 页面上,选择 Next

  6. 审核页面上,选择我确认,AWS CloudFormation 可能创建 IAM 资源。,然后选择创建

    AWS CloudFormation 开始创建 MyStateMachine 堆栈,并显示 CREATE_IN_PROGRESS 状态。在此过程完成后,AWS 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:启动状态机执行

在创建您的 Lambda 状态机后,可以开始执行。

启动状态机执行

  1. 打开 Step Functions 控制台,然后选择您使用 AWS CloudFormation 创建的状态机的名称。

  2. MyStateMachine-ABCDEFGHIJ1K 页面上,选择 New execution

    此时将显示 New execution 页面。

  3. (可选) 为帮助您标识执行,您可以在 Enter an execution name 框中为执行指定一个 ID。如果未输入 ID,Step Functions 将自动生成一个唯一 ID。

    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 Amazon CloudWatch。为确保您可以跟踪 CloudWatch 指标,请选择一个只使用 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