Traffic Shifting with Aliases

Traffic Shifting with Aliases in AWS Lambda allows developers to shift a percentage of traffic to different versions of a Lambda function. This technique is beneficial for gradually deploying new features, A/B testing, or rolling back changes quickly if issues arise.

Understanding the following key concepts is crucial for implementing traffic shifting:

• Aliases: Named references to specific Lambda function versions.
• Versions: Immutable snapshots of your Lambda function code and configuration.
• Traffic Shifting: The process of distributing requests across different versions of a Lambda function.

Follow these steps to implement traffic shifting with aliases:

1. Deploy a new version of your Lambda function.
2. Create an alias pointing to the current version of the function.
3. Update the alias to shift traffic to the new version incrementally:

Use the AWS CLI or SDK to adjust the traffic percentage.

4. Monitor the performance and error metrics during the shift.
5. Roll back traffic if necessary by updating the alias to the previous version.

Example CLI command to update an alias:

aws lambda update-alias --function-name myFunction --name myAlias --function-version 2 --routing-config '{"AdditionalVersionWeights": {"1": 0.5}}'

Implement the following best practices for effective traffic shifting:

• Conduct tests in a staging environment before production.
• Monitor logs and metrics closely during traffic shifts.
• Gradually increase traffic percentage to minimize risks.
• Ensure proper error handling in your function code.