EC2 Auto Scaling Group Not Launching Instances Despite Proper Configuration
I've been working on this all day and Quick question that's been bugging me - I'm working with an scenario with my EC2 Auto Scaling group where it seems to be configured correctly, but it isn't launching any instances. I've set a minimum of 1 instance, and the desired capacity is also set to 1. My launch template is configured with the latest Amazon Linux 2 AMI, and I can manually launch instances using the same template without any issues. Here are snippets of my configuration: ```json { "LaunchTemplateName": "MyLaunchTemplate", "Version": "1", "LaunchTemplateData": { "ImageId": "ami-0abcdef1234567890", "InstanceType": "t2.micro", "IamInstanceProfile": { "Arn": "arn:aws:iam::123456789012:instance-profile/MyInstanceProfile" }, "SecurityGroupIds": ["sg-0123456789abcdef0"], "UserData": "IyEvYmluL2Jhc2gKZXhwb3J0IFVSTCAkaHR0cHM6Ly96b2RpbS5jb20v" } } ``` I've also set the scaling policies correctly and ensured that they are attached to the Auto Scaling group. The health check type is set to EC2, and I've disabled instance protection to allow the Auto Scaling group to terminate instances if needed. Despite this, the Auto Scaling group status remains at "In Service" with zero instances running. I checked for any CloudWatch alarms, but none are in an alarm state that would trigger scaling actions. The only message I see in the Auto Scaling group activity history is "Failed to launch instance" with no further details. I've tried the following troubleshooting steps: - Verified the IAM role associated with the Auto Scaling group has the necessary permissions. - Ensured there are no VPC/subnet issues preventing instance launch. - Checked for service limits on EC2 instances in my account. - Reviewed the instance launch status via the EC2 console but found no failed attempts. Is there something I've missed in the setup, or is there a common pitfall with Auto Scaling groups I should be aware of? I'm working on a CLI tool that needs to handle this. What's the best practice here?