AWS Lambda Function Weighted Alias

The Weighted Alias for Lambda Functions was announced at AWS re:Invent 2017. This allows you to develop serverless applications and have a Lambda Alias specify the percentage of traffic that gets directed between to 2 different versions of the Lambda Function. One good example of using a weighted alias is to gradually deploy a new version of a Lambda Function into production.

In the example below I have an AWS Lambda Function that has 2 versions, v1 and v2. I created a weighted alias, called Prod, that sends 67% of the Lambda traffic to v1 and 33% of the Lambda traffic to the new v2. The weighted alias allows me to begin migrating the new version of the Lambda Function into production in a controlled manner.

AWS Weighted Alias for Lambda Function

The new AWS Lambda Console shows the optional ability to specify 2 versions of the Lambda Function and the percentage of traffic directed to each to create a Weighted Lambda Alias.

AWS Weighted Lambda Alias

There were a lot more announcements concerning serverless applications at re:Invent 2017. I also mentioned the new Cloud9 IDE for developing Lambda Functions.