⭐⭐⭐ Important Topic

🎯 Amazon EventBridge

EventBridge is a serverless event bus that connects your applications using events. For Domain 4, it's used for automated remediation, scheduled monitoring workflows, and event-driven alerting and responses.

🔑 Covers: Event Bus · Rules · Targets · Scheduled Events · Automated Remediation

🎯 What is Amazon EventBridge?

Amazon EventBridge
A serverless event bus service that routes events from sources (AWS services, your applications, SaaS tools) to targets (Lambda, SQS, SNS, Step Functions, etc.) based on rules you define. Think of it as a smart routing system: "IF this event happens, THEN trigger this action." Previously known as CloudWatch Events (and still uses the same underlying infrastructure).

📋 Key EventBridge Concepts

🌊 Event Bus

The channel events flow through. AWS has a default event bus that receives events from all AWS services. You can create custom buses for your own application events.

📋 Rule

Defines which events to match and what target to invoke. Rules use event patterns (JSON matching) or schedules (cron/rate expressions) to trigger targets.

🎯 Target

What gets triggered when a rule matches. Examples: Lambda function, SQS queue, SNS topic, Step Functions, ECS task, CloudWatch Logs.

⚙️ Two Types of Rules

📅 Scheduled Rules

Run on a time schedule. Like a cron job in the cloud.

Rate expression: rate(5 minutes), rate(1 day)

Cron expression: cron(0 8 * * ? *) = every day at 8am UTC

Use cases: Daily reports, cleanup jobs, periodic health checks, database backups.

📡 Event Pattern Rules

Match specific events from AWS services or your apps.

Example: "When an EC2 instance is terminated" or "When a CodePipeline deployment fails" or "When a DynamoDB table is deleted"

Use cases: Automated responses to AWS events, security alerting, compliance enforcement.

🔧 Automated Remediation Examples

Event (Trigger)Target (Action)What it does
CloudWatch Alarm state changes to ALARMLambda functionAuto-restart a stuck service, scale out resources
EC2 instance state changes to "stopped"Lambda functionAlert operations team via Slack/PagerDuty
CodePipeline pipeline failsSNS topic → EmailAlert developer of failed deployment
S3 bucket policy changes (via CloudTrail)Lambda functionRevert unauthorized policy changes automatically
Rate(1 hour)Lambda functionRun hourly health check report
IAM user created (via CloudTrail)Lambda functionEnforce tagging, send notification to security team
🎯 Exam Tip
EventBridge is the answer for: "automated remediation triggered by AWS events", "scheduled Lambda execution", "react to AWS service state changes", "event-driven workflow automation". The key phrase is "event-driven" + "automated response".