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AWS Lambda 1.4.0Last updated in version 1.4.0

Lambda Alias Module

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This module creates an AWS Lambda alias that points to a specific version of a Lambda function. An alias is a named pointer to a Lambda function version, allowing you to invoke a specific version using a stable endpoint without needing to know the underlying version number.

Aliases are useful for:

  • Stable endpoints: Invoke a function via an alias name (e.g., live, staging) rather than a version number.
  • Traffic shifting: Gradually shift traffic between two versions using weighted routing for canary or blue/green deployments.
  • Function URLs and event source mappings: Point triggers at an alias so you can update the underlying version without reconfiguring consumers.

How do you do weighted traffic shifting?​

You can use the routing_config variable to split traffic between two versions of a Lambda function. This is useful for canary deployments where you want to gradually shift traffic to a new version:

module "lambda_alias" {
  source = "git::git@github.com:gruntwork-io/terraform-aws-lambda.git//modules/lambda-alias?ref=v1.0.0"

  name             = "live"
  function_name    = module.my_lambda_function.function_name
  function_version = "2"

  routing_config = {
    additional_version_weights = {
      "3" = 0.1  # Send 10% of traffic to version 3
    }
  }
}

In this example, 90% of traffic goes to version 2 (the primary version) and 10% goes to version 3. You can adjust the weight from 0.0 to 1.0 as you gain confidence in the new version.

Background info​

For more information on AWS Lambda, how it works, and how to configure your functions, check out the lambda module documentation.

Sample Usage​

main.tf

# ------------------------------------------------------------------------------------------------------
# DEPLOY GRUNTWORK'S LAMBDA-ALIAS MODULE
# ------------------------------------------------------------------------------------------------------

module "lambda_alias" {

  source = "git::git@github.com:gruntwork-io/terraform-aws-lambda.git//modules/lambda-alias?ref=v1.4.0"

  # ----------------------------------------------------------------------------------------------------
  # REQUIRED VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # The Lambda function name or ARN to associate with the alias
  function_name = <string>

  # Lambda function version for which to create the alias
  function_version = <string>

  # Name for the alias
  name = <string>

  # ----------------------------------------------------------------------------------------------------
  # OPTIONAL VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # Description of the alias
  description = ""

  # Lambda alias routing configuration for weighted traffic shifting. Set
  # additional_version_weights to a map of version number to weight (0.0 - 1.0).
  routing_config = null

}


Reference​

Required​

function_namestringrequired

The Lambda function name or ARN to associate with the alias

function_versionstringrequired

Lambda function version for which to create the alias

namestringrequired

Name for the alias

Optional​

descriptionstringoptional

Description of the alias

""
routing_configobject(…)optional

Lambda alias routing configuration for weighted traffic shifting. Set additional_version_weights to a map of version number to weight (0.0 - 1.0).

object({
    additional_version_weights = map(number)
  })
null