Canary deployment is a progressive release strategy used in AWS that reduces risk by gradually rolling out changes to a small subset of users before deploying to the entire infrastructure. The name comes from the historical practice of using canary birds in coal mines to detect dangerous gases.
In…Canary deployment is a progressive release strategy used in AWS that reduces risk by gradually rolling out changes to a small subset of users before deploying to the entire infrastructure. The name comes from the historical practice of using canary birds in coal mines to detect dangerous gases.
In AWS, canary deployments work by routing a small percentage of traffic (typically 1-10%) to the new version of your application while the majority of users continue using the stable version. This approach allows you to monitor the new version's performance, error rates, and user experience in a production environment with minimal impact.
AWS services that support canary deployments include:
1. **AWS Lambda**: Using Lambda aliases with weighted traffic shifting, you can configure a canary deployment that sends a specified percentage of invocations to the new function version.
2. **AWS CodeDeploy**: Offers built-in canary deployment configurations like Canary10Percent5Minutes, which shifts 10% of traffic initially, then the remaining 90% after five minutes if no alarms trigger.
3. **Amazon API Gateway**: Supports canary releases for API stages, allowing you to test new API versions with a portion of your traffic.
4. **Elastic Load Balancing**: You can configure weighted target groups to distribute traffic between old and new application versions.
Key benefits of canary deployments include:
- Early detection of issues with minimal user impact
- Quick rollback capability if problems arise
- Real production environment testing
- Reduced deployment risk
Best practices involve setting up CloudWatch alarms to monitor key metrics during the canary phase. If error rates exceed thresholds, automatic rollback occurs. This strategy is particularly valuable for mission-critical applications where downtime or bugs could significantly impact users or business operations.
Canary deployments represent a middle ground between all-at-once deployments and blue-green deployments, offering controlled risk management for continuous delivery pipelines.
A Canary deployment is a deployment strategy where you gradually shift traffic from the current version of your application to a new version. The name comes from the historical practice of using canaries in coal mines to detect dangerous gases - similarly, canary deployments help you detect problems early before they affect all users.
In AWS, canary deployments route a small percentage of traffic (typically 10%) to the new version first, while the majority of traffic continues to go to the existing version. After a specified waiting period and validation, the remaining traffic shifts to the new version.
Why is Canary Deployment Important?
• Risk Mitigation: By exposing only a small subset of users to the new version initially, you minimize the blast radius of potential issues • Early Problem Detection: Issues can be identified and addressed before they impact your entire user base • Controlled Rollback: If problems are detected, rolling back affects only the small percentage of traffic already shifted • Real-World Testing: Allows testing with actual production traffic and user behavior • Gradual Confidence Building: Teams can validate changes incrementally before full deployment
How Canary Deployment Works in AWS
AWS Lambda Canary Deployments: • Uses Lambda aliases with weighted traffic shifting • AWS SAM supports deployment preferences like Canary10Percent5Minutes, Canary10Percent10Minutes, Canary10Percent15Minutes, and Canary10Percent30Minutes • Traffic shifts 10% initially, then 100% after the specified time period • CodeDeploy manages the traffic shifting automatically • Pre-traffic and post-traffic hooks can run Lambda functions for validation
AWS CodeDeploy Canary for EC2/ECS: • Shifts traffic in two increments • First increment routes a specified percentage to the new version • Second increment routes remaining traffic after validation period • Supports automatic rollback based on CloudWatch alarms
Example Configuration: In SAM template: DeploymentPreference: Type: Canary10Percent10Minutes Alarms: - !Ref AliasErrorMetricGreaterThanZeroAlarm Hooks: PreTraffic: !Ref PreTrafficLambdaFunction PostTraffic: !Ref PostTrafficLambdaFunction
Canary vs Other Deployment Strategies
• Canary: Two-step traffic shift (small percentage first, then remainder) • Linear: Traffic shifts in equal increments at regular intervals • All-at-once: All traffic shifts to new version instantly (highest risk) • Blue/Green: Complete switch between two identical environments
Exam Tips: Answering Questions on Canary Deployment Strategy
1. Recognize the Keyword Patterns: Look for scenarios mentioning 'gradual traffic shift,' 'minimize risk,' 'test with small percentage of users,' or 'two-phase deployment'
2. Know the Percentage Options: AWS canary options typically start with 10% traffic shift. Memorize: Canary10Percent5Minutes, Canary10Percent10Minutes, Canary10Percent15Minutes, Canary10Percent30Minutes
3. Understand the Difference from Linear: Canary = two steps (10% then 90%). Linear = multiple equal steps over time. This distinction frequently appears in exam questions
4. Associate with CodeDeploy: When questions mention traffic shifting with Lambda or ECS, think CodeDeploy as the underlying service managing the deployment
5. Remember Rollback Triggers: Canary deployments can automatically rollback based on CloudWatch alarms - this is a common exam topic
6. Hooks are Important: PreTraffic and PostTraffic hooks allow validation. Questions may ask about running tests before or after traffic shifts
7. Time-Based Questions: The number in the deployment type (5, 10, 15, 30 minutes) represents the wait time between the first and second traffic shift
8. Scenario Recognition: If a question describes needing to 'validate a new version with production traffic while limiting exposure,' canary is likely the answer
9. SAM Integration: Know that AWS SAM templates use DeploymentPreference to configure canary deployments for Lambda functions
10. Cost Consideration: Canary deployments run both versions simultaneously during the deployment window, which may have cost implications mentioned in scenarios