如何使用 Terraform 定义 cloundwatch 事件规则来触发 StepFunction statemachine

Question

我已经在Terraform中定义了一个StepFunction状态机的创建，现在我想设置一个定时器每天触发状态机，我想可能使用cloudwatch事件规则是一个不错的选择，我知道如何设置事件触发 Lambda 的规则：

resource "aws_cloudwatch_event_rule" "lambda_event_rule" {
  name                = xxx
  schedule_expression = xxx
  description         = xxx
}

resource "aws_cloudwatch_event_target" "lambda_event_target" {
  target_id = xxx
  rule      = aws_cloudwatch_event_rule.lambda_event_rule.name
  arn       = xxx
}

#I must setup the right permissions using 'aws_lambda_permission' 
#see: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudwatch_event_target

resource "aws_lambda_permission" "lambda_event_permission" {
  statement_id  = xxx
  action        = "lambda:InvokeFunction"
  function_name = xxx
  principal     = "events.amazonaws.com"
  source_arn    = aws_cloudwatch_event_rule.lambda_event_rule.name
}

但是如何设置触发状态机的权限部分？我找不到任何关于它的例子，我错过了什么吗？是因为我们不需要状态机的权限配置吗？有人可以帮忙吗？

以下是我到目前为止使用 cloudwatch 事件规则触发状态机的内容：

resource "aws_cloudwatch_event_rule" "step_function_event_rule" {
  name                = xxx
  schedule_expression = xxx
  description         = xxx
}

resource "aws_cloudwatch_event_target" "step_function_event_target" {
  target_id = xxx
  rule      = aws_cloudwatch_event_rule.step_function_event_rule.name
  arn       = xxx
}


?????What else should I add here?

PS: 我发现有人在问类似的问题here，但还没有答案。

Answer 1

我不太熟悉 terraform，但它似乎遵循与官方文档类似的模式。对于目标； https://docs.aws.amazon.com/eventbridge/latest/APIReference/API_PutTargets.html >> 请参阅“将 Step Functions 状态机添加为目标”部分

{
    "Rule": "testrule", 
    "Targets": [
           {
        "RoleArn": "arn:aws:iam::123456789012:role/MyRoleToAccessStepFunctions"
        "Arn":"arn:aws:states:us-east-1:123456789012:stateMachine:HelloWorld"
      }
    ]
}

这告诉我你需要传递角色和 arn。所以以你的例子为例，这是你可能需要填写的东西

resource "aws_cloudwatch_event_rule" "step_function_event_rule" {
  name                = <something unique>
  schedule_expression = <syntax described in https://docs.aws.amazon.com/eventbridge/latest/userguide/scheduled-events.html>
  description         = <something descriptive>
}

resource "aws_cloudwatch_event_target" "step_function_event_target" {
  target_id = <something unique>
  rule      = aws_cloudwatch_event_rule.step_function_event_rule.name
  arn       = <step function arn>
  role_arn  = <role that allows eventbridge to start execution on your behalf>
}

Answer 2

    resource "aws_lambda_permission" "lambda_event_permission" {
     statement_id  = xxx
     action        = "lambda:InvokeFunction"
     function_name = xxx
     principal     = "events.amazonaws.com"
     source_arn    = aws_cloudwatch_event_rule.lambda_event_rule.name
    }

在您的情况下根本不需要部分，只需要按照说明“为了能够让 EventBridge 规则调用您的 AWS Lambda 函数或 SNS 主题”。

正如blr在他的回答中所说，你需要在aws_cloudwatch_event_target中添加role_arn，使用 assume_role_policy 设置角色，授予对 states.amazonaws.com 和 events.amazonaws.com 的访问权限，并附加到此角色的额外策略如下：

    data "aws_iam_policy_document" "CW2SF_allowexec" {
      statement {
        actions = [
          "sts:AssumeRole"
        ]

        principals {
          type = "Service"
          identifiers = [
            "states.amazonaws.com",
            "events.amazonaws.com"
          ]
        }
      }
    }

    resource "aws_iam_role" "CW2SF_allowexec" {
      name               = "AWS_Events_Invoke-StepFunc"
      assume_role_policy = data.aws_iam_policy_document.CW2SF_allowexec.json
    }

    resource "aws_iam_role_policy" "state-execution" {
      name        = "CW2SF_allowexec"
      role   = aws_iam_role.CW2SF_allowexec.id

      policy = <<EOF
    {
      "Version": "2012-10-17",
      "Statement": [
          {
              "Effect": "Allow",
              "Action": [
                  "states:StartExecution"
              ],
              "Resource": [          
"arn:aws:states:${var.region}:${data.aws_caller_identity.current.account_id}:stateMachine:data-pipeline-incremental"
          ]
      }
  ]
}
EOF
}

您需要使用AssumeRole在CloudWatch和StepFunctions之间建立信任，然后在角色上附加一个内联或托管策略，专门允许这个角色启动状态机的执行。

如何使用 Terraform 定义 cloundwatch 事件规则来触发 StepFunction statemachine

How to use Terraform to define cloundwatch event rules to trigger StepFunction statemachine

state-machine

amazon-web-services

terraform

aws-step-functions

amazon-cloudwatch-events