AWS CodeDeploy

Core concept: CodeDeploy automates application deployments to EC2, Lambda, and ECS with traffic shifting, rollback, and lifecycle hooks.

What Is CodeDeploy?

CodeDeploy is like a smart deployment manager. Instead of manually updating your servers one by one, CodeDeploy orchestrates the rollout — shifting traffic gradually, running health checks, and automatically rolling back if something goes wrong.

Deployment Targets

Platform	Deployment Type	Agent	Traffic Control
EC2/On-Premises	In-place or Blue/Green	✅ CodeDeploy Agent	ASG, tags
Lambda	Traffic shifting (aliases)	❌ Not needed	Alias routing
ECS	Blue/Green (ALB)	❌ Not needed	Target group swap

Deployment Strategies

EC2 Deployment Strategies

Strategy	Description	Downtime
AllAtOnce	Deploy to all instances simultaneously	⚠️ Brief
HalfAtATime	Deploy to 50% of instances, then remaining	Minimal
OneAtATime	Deploy to one instance at a time	None
Blue/Green	Create new ASG, shift ALB traffic	None

Lambda Deployment Configurations

Configuration	Behavior
LambdaAllAtOnce	Shift 100% traffic immediately
LambdaCanary10Percent5Minutes	10% → wait 5 min → 90%
LambdaCanary10Percent10Minutes	10% → wait 10 min → 90%
LambdaCanary10Percent15Minutes	10% → wait 15 min → 90%
LambdaCanary10Percent30Minutes	10% → wait 30 min → 90%
LambdaLinear10PercentEvery1Minute	10% → 20% → ... → 100% (every 1 min)
LambdaLinear10PercentEvery2Minutes	10% → 20% → ... → 100% (every 2 min)
LambdaLinear10PercentEvery3Minutes	10% → 20% → ... → 100% (every 3 min)
LambdaLinear10PercentEvery10Minutes	10% → 20% → ... → 100% (every 10 min)

Canary vs Linear

Canary = shift small %, wait, then shift ALL remaining
Linear = shift same % at regular intervals until 100%

ECS Deployment Configurations

Configuration	Behavior
ECSAllAtOnce	Shift 100% immediately
ECSCanary10Percent5Minutes	Same as Lambda canary
ECSLinear10PercentEvery1Minute	Same as Lambda linear

Lifecycle Hooks

EC2/On-Premises Hook Order

ApplicationStop        ← Stop current app
    ↓
DownloadBundle         ← Download new revision from S3/GitHub
    ↓
BeforeInstall          ← Pre-install tasks (backup, decrypt)
    ↓
Install                ← Copy files to destination
    ↓
AfterInstall           ← Post-install (set permissions, config)
    ↓
ApplicationStart       ← Start the application
    ↓
ValidateService        ← Run health checks ← MOST IMPORTANT

Lambda Hook Order

BeforeAllowTraffic     ← Run pre-traffic validation Lambda
    ↓
AllowTraffic           ← Traffic shifted to new version
    ↓
AfterAllowTraffic      ← Run post-traffic validation Lambda

Pre-Traffic Hook Example (Lambda)

public class PreTrafficHook implements RequestHandler<Map<String, Object>, Void> {
    
    private final CodeDeployClient codeDeploy = CodeDeployClient.create();
    
    public Void handleRequest(Map<String, Object> event, Context context) {
        String deploymentId = (String) event.get("DeploymentId");
        String lifecycleEventHookExecutionId = (String) event.get("LifecycleEventHookExecutionId");
        
        String status = "Succeeded";
        try {
            // Test the new Lambda version
            invokeNewVersion();
            validateResponse();
        } catch (Exception e) {
            status = "Failed";  // This triggers automatic rollback
        }
        
        codeDeploy.putLifecycleEventHookExecutionStatus(
            PutLifecycleEventHookExecutionStatusRequest.builder()
                .deploymentId(deploymentId)
                .lifecycleEventHookExecutionId(lifecycleEventHookExecutionId)
                .status(status)
                .build());
        
        return null;
    }
}

appspec.yml

Lambda

version: 0.0
Resources:
  - MyLambdaFunction:
      Type: AWS::Lambda::Function
      Properties:
        Name: "OrderProcessor"
        Alias: "live"
        CurrentVersion: "1"
        TargetVersion: "2"
Hooks:
  - BeforeAllowTraffic: "arn:aws:lambda:us-east-1:123:function:PreTrafficHook"
  - AfterAllowTraffic: "arn:aws:lambda:us-east-1:123:function:PostTrafficHook"

EC2

version: 0.0
os: linux
files:
  - source: /
    destination: /var/www/html
permissions:
  - object: /var/www/html
    owner: apache
    group: apache
    mode: "755"
hooks:
  ApplicationStop:
    - location: scripts/stop-server.sh
      timeout: 120
  BeforeInstall:
    - location: scripts/install-deps.sh
      timeout: 300
  AfterInstall:
    - location: scripts/set-permissions.sh
  ApplicationStart:
    - location: scripts/start-server.sh
      timeout: 120
  ValidateService:
    - location: scripts/health-check.sh
      timeout: 60

ECS Blue/Green

version: 0.0
Resources:
  - TargetService:
      Type: AWS::ECS::Service
      Properties:
        TaskDefinition: "arn:aws:ecs:us-east-1:123:task-definition/my-task:2"
        LoadBalancerInfo:
          ContainerName: "api-container"
          ContainerPort: 8080
Hooks:
  - BeforeInstall: "LambdaValidateDatabases"
  - AfterInstall: "LambdaRunIntegrationTests"
  - AfterAllowTestTraffic: "LambdaVerifyGreenTargetGroup"
  - BeforeAllowTraffic: "LambdaCheckHealth"
  - AfterAllowTraffic: "LambdaVerifyProductionShifting"

Rollback Behavior

Trigger	Rollback
Any lifecycle hook fails	✅ Automatic
CloudWatch alarm breached	✅ Automatic (if configured)
Manual trigger	✅ Via console/CLI

Important

CodeDeploy "rollback" = redeploy the previous revision. It doesn't reverse changes — it deploys the old version as a new deployment.

Deployment Groups

Config	Description
Deployment group	Target instances (EC2 tags, ASG, ECS service)
Deployment config	Traffic shifting strategy
Service role	IAM role for CodeDeploy
Alarms	CloudWatch alarms that trigger rollback
Triggers	SNS notifications on deployment events
Auto-rollback	Enable/disable on failure or alarm

DVA-C02 Exam Tips

CodeDeploy Exam Cheat Sheet

Canary = shift small %, wait, shift rest. Linear = gradual increment
Hook failure = automatic rollback
Rollback = redeploy previous version (new deployment)
EC2 supports in-place AND blue/green. ECS = blue/green only
Lambda uses aliases for traffic shifting
BeforeAllowTraffic = pre-traffic validation (Lambda platform)
ValidateService = health check (EC2 platform)
appspec.yml = mandatory deployment specification file
CodeDeploy Agent needed on EC2, NOT needed for Lambda/ECS
ECS blue/green requires ALB with two target groups

Practice Questions

Q1. ValidateService hook fails. What happens?

A) Deployment marked failed, no rollback
B) Automatic rollback to previous version
C) Hook retries 3 times
D) Deployment continues with warning

✅ Answer & Explanation

B — Any hook failure triggers automatic rollback by redeploying the last successful version.

Q2. 10% traffic to new Lambda, wait 5 min, then 100%. Which config?

A) LambdaLinear10PercentEvery1Minute
B) LambdaAllAtOnce
C) LambdaCanary10Percent5Minutes
D) LambdaBlueGreen

✅ Answer & Explanation

C — Canary10Percent5Minutes: 10% immediate → monitor 5 min → shift remaining 90%.

Q3. ECS Fargate needs zero-downtime deployment. Which strategy?

A) In-place
B) Rolling update
C) Blue/Green with ALB target group swap
D) AllAtOnce

✅ Answer & Explanation

C — ECS Fargate with CodeDeploy supports only Blue/Green via ALB target group swapping.

🔰 What Is CodeDeploy?

Deployment Targets

Deployment Strategies

EC2 Deployment Strategies

Lambda Deployment Configurations

ECS Deployment Configurations

Lifecycle Hooks

EC2/On-Premises Hook Order

Lambda Hook Order

Pre-Traffic Hook Example (Lambda)

appspec.yml

Lambda

EC2

ECS Blue/Green

Rollback Behavior

Deployment Groups

🎯 DVA-C02 Exam Tips

Practice Questions

🔗 Resources

What Is CodeDeploy?

DVA-C02 Exam Tips

Resources