EC2 Auto Scaling Log Collection Solutions Comparison

Solution 1: Lifecycle Hook with Systems Manager

Architecture

• Auto Scaling Group

• Lifecycle Hook

• EventBridge

• Lambda

• Systems Manager

• S3 Bucket

Implementation

1. Lifecycle hook triggers on instance termination

2. EventBridge rule captures the event

3. Lambda function executes

4. Systems Manager runs document on instance

5. Logs copied to S3

6. Instance termination continues

Pros

1. Complete control over the log collection process

2. Guaranteed log collection before instance termination

3. Flexible log processing capabilities

4. Custom error handling

5. Ability to extend functionality easily

6. No additional cost for log streaming

7. Direct S3 storage without intermediate steps

Cons

1. Complex architecture with multiple components

2. More points of failure

3. Higher maintenance overhead

4. Requires careful timeout management

5. Network dependencies during copy

6. Resource intensive during copy

7. Potential instance termination delays

8. Manual recovery if process fails

Solution 2: CloudWatch Agent

Architecture

• Auto Scaling Group

• CloudWatch Agent

• CloudWatch Logs

• S3 Bucket (optional)

Implementation

1. Install CloudWatch Agent via user data or AMI

2. Configure log streaming

3. Set up log retention policies

4. Configure S3 export (if needed)

# CloudWatch Agent Configuration
{
    "agent": {
        "run_as_user": "root"
    },
    "logs": {
        "logs_collected": {
            "files": {
                "collect_list": [
                    {
                        "file_path": "/var/log/application/*.log",
                        "log_group_name": "/ec2/application",
                        "log_stream_name": "{instance_id}",
                        "retention_in_days": 30
                    }
                ]
            }
        },
        "force_flush_interval": 5
    }
}

Pros

1. Near real-time log streaming

2. Built-in retry mechanisms

3. Simple architecture

4. Managed service reliability

5. Automatic scaling

6. No instance termination dependencies

7. Built-in monitoring and alerts

8. Unified logging across fleet

9. Search and analysis capabilities

10. Automatic handling of instance failures

Cons

1. Additional cost for CloudWatch Logs

2. Log format restrictions

3. Potential streaming delays

4. Regional data transfer costs

5. Log retention management needed

6. Additional network bandwidth usage

7. Limited log processing capabilities

8. Storage costs in both CloudWatch and S3

Recommendation

CloudWatch Agent solution is recommended for:

• Production environments requiring reliability

• Applications needing real-time log analysis

• Regulated environments requiring audit trails

• Large-scale deployments

• Teams with limited operational resources

Lifecycle Hook solution is better for:

• Custom log processing requirements

• Cost-sensitive environments

• Specific compliance requirements

• Applications with complex log structures

• Environments with limited CloudWatch quotas

Cost Considerations

Lifecycle Hook Solution

• S3 storage costs

• Lambda invocations

• Systems Manager operations

• No streaming costs

CloudWatch Agent Solution

• CloudWatch Logs ingestion

• CloudWatch Logs storage

• S3 export costs (if needed)

• Data transfer costs

Security Considerations

Both Solutions

• IAM role configuration

• Network security

• Data encryption

• Access logging

Additional for CloudWatch Agent

• Agent security

• Log group permissions

• Cross-account access

Operational Considerations

Lifecycle Hook Solution

• Component monitoring

• Error handling

• Timeout management

• Recovery procedures

• Scaling limitations

CloudWatch Agent Solution

• Agent health monitoring

• Quota management

• Log group organization

• Retention policies