Eventbridge scheduler

Question

Hi,
I was testing the EventBridge to simply stop or start my EC2 (linux). I have created the roles and policy that are needed but it looks like the event failing to invoke my EC2!!
Strange part is, I did the same things in 2 accounts, in our prodcution account it works but when try it in our sandbox server wont start or stop my EC2

this is my policy:
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": "ec2:StartInstances",
            "Resource": "arn:aws:ec2:eu-central-1:XXXXXXXXXX:instance/i-07d8c13fXXXXXa0",
            "Effect": "Allow"
        }
    ]
}

and this is the Trusted entities of the role:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "scheduler.amazonaws.com"
            },
            "Action": "sts:AssumeRole",
            "Condition": {
                "StringEquals": {
                    "aws:SourceArn": "arn:aws:scheduler:eu-central-1:XXXXXXXXX:schedule/default/StartLinuxServer",
                    "aws:SourceAccount": "XXXXXXXXXX"
                }
            }
        }
    ]
}

The SSM has access to the EC2 and have already updated the SSM agent.

any idea, why it works in one account and not in other? the only different is server in working account is in a Private subnet and in sandbox is in default public subnet

Thanks

Answer

this is my event policy
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": "ec2:StartInstances",
            "Resource": "arn:aws:ec2:eu-central-1:xxxxxxxxxxx45:instance/i-02307ed149403dd12",
            "Effect": "Allow"
        }
    ]
}

and its trust relation

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "scheduler.amazonaws.com"
            },
            "Action": "sts:AssumeRole",
            "Condition": {
                "StringEquals": {
                    "aws:SourceArn": "arn:aws:scheduler:eu-central-1:XXXXXXXXXXX45:schedule/default/linuxStartSchedule",
                    "aws:SourceAccount": "Xxxxxxxxxxxx45"
                }
            }
        }
    ]
}

I dont think there is a problem with the IAM roles, becuse I use the same roles in my pro enviorment and it works without any problem! when use them in my sandbox account it wont work

Answer

Hello.

First of all, you cannot stop EC2 with "ec2:StartInstances" alone.  
"ec2:StopInstances" is also required to stop EC2.

By the way, is the ARN set in the trust policy correct?  
For example, how about making it available to all EventBridge schedulers as follows?  
```
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "scheduler.amazonaws.com"
            },
            "Action": "sts:AssumeRole"
        }
    ]
}
```
I think the following blog will be helpful for the settings itself.  
https://dev.to/aws-builders/easy-setup-for-ec2-stop-jobs-with-amazon-eventbridge-scheduler-4lpg

Eventbridge scheduler

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