This AWS SAM template is part of notify-on-running-ec2-instances. The template provisions all the required AWS resources.

notify-on-running-ec2-instances-template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: SAM template - send notifications for running ec2 instances
Parameters:
  SlackWebhookURL:
    Type: String
    Description: Slack webhook url for sending notifications
Resources:
  monitorEC2InstancesFunction:
    Type: AWS::Serverless::Function
    Properties:
      Description: This function will monitor all EC2 instances on a schedule and send a slack notification when any are found running.
      Handler: src/monitor-ec2-instances.lambda_handler
      Runtime: python3.7
      Timeout: 300
      Events:
        CloudWatchEventsSchedule:
          Type: Schedule
          Properties:
            Schedule: "cron(0 18 * * ? *)"
            Name: CheckForRunningEC2Instances
            Description: Check for running ec2 instances
            Enabled: True
      Policies:
      - AWSLambdaBasicExecutionRole
      - EC2DescribePolicy: {}
      Environment:
        Variables:
          SLACK_WEBHOOK_URL: !Ref SlackWebhookURL