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Create an EC2 - Instance....

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Create IAM Policy & IAM Role

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ],
      "Resource": "arn:aws:logs:*:*:*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "ec2:Start*",
        "ec2:Stop*"
      ],
      "Resource": "*"
    }
  ]
}

Enter a name. For example  itinfrasollambdaec2

Create a Lambda function

import boto3
region = 'eu-central-1'
instances = ['i-0bf45f32ee3047d76']
ec2 = boto3.client('ec2', region_name=region)

def lambda_handler(event, context):
    ec2.stop_instances(InstanceIds=instances)
    print('stopped your instances: ' + str(instances))

import boto3
region = 'eu-central-1'
instances = ['i-0bf45f32ee3047d76']
ec2 = boto3.client('ec2', region_name=region)

def lambda_handler(event, context):
    ec2.start_instances(InstanceIds=instances)
    print('started your instances: ' + str(instances))

Sources:

https://it-infrastructure.solutions/spinning-up-your-first-ec2-instance-aws/

Tutorial: Schedule AWS Lambda functions using EventBridge - Amazon EventBridge
Learn how to use Amazon EventBridge to schedule a Lambda function.
Amazon EventBridge

https://aws.amazon.com/de/premiumsupport/knowledge-center/start-stop-lambda-cloudwatch/