terraform-provider-aws: Breaking change on data source aws_lambda_function introduced in version 2.0.0

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Terraform Version

Terraform: 0.10.8 Terraform AWS provider: 2.11.0

Affected Resource(s)

Data source aws_lambda_function

Terraform Configuration Files

data "aws_lambda_function" "lambda" {
  function_name = "myFunction"
  qualifier     = ""
}

resource "aws_cloudfront_distribution" "distribution" {
  default_cache_behavior {
    lambda_function_association {
      event_type   = "origin-response"
      lambda_arn   = "${data.aws_lambda_function.lambda.qualified_arn}"
      include_body = false
    }
  }
}

Expected Behavior

The Lambda function qualified_arn should be qualified by the latest version number instead of $LATEST

Actual Behavior

The Lambda function qualified_arn is qualified with $LATEST

References

The breaking change has been introduced in the PR https://github.com/terraform-providers/terraform-provider-aws/pull/7663 which has been merged into the provider version 2.0.0.

The dataSourceAwsLambdaFunctionRead() implementation switched from using resourceAwsLambdaFunctionRead() (defined in resource_aws_lambda_function.go) to a new (de-coupled) implementation.

The resourceAwsLambdaFunctionRead() implementation has support to fetch the latest version number in case qualifierExistance is falsy (see code here), while the new one doesn’t have it.

Questions, please:

Is there any interest to fix the breaking change?
If not, shouldn’t we document it in the upgrade guide?
If not, is there any known workaround to get the latest version number of a Lambda function defined as a data source?

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 16
Comments: 16

Most upvoted comments

In order to associate a lambda functions with a CloudFront distribution as Lambda@Edge, it is required to provide a version number.

I would be interested to retrieve the latest fixed version number of a given lambda. Is this possible currently by using aws_lambda_function data source?

data "aws_lambda_function" "example_lambda_edge" {
  function_name = "example"
  qualifier     = ""
}

resource "aws_cloudfront_distribution" "example_distribution" {
  # ...

  default_cache_behavior {
    # ...

    lambda_function_association {
      event_type   = "viewer-request"
      # Problem: the qualifier here will be "$LATEST" which will not work in that case.
      lambda_arn   = data.aws_lambda_function.example_lambda_edge.qualified_arn
    }
  }
}

ghost on Aug 13, 2019

If you are using the AWS Console @eretica you will need to create the lambda in us-east-1 N. Virgina. Then you will need to publish a version that will give you a version number.

You can check out the doco here https://docs.aws.amazon.com/lambda/latest/dg/configuration-versions.html

In Terraform you need to make sure that your region is set to us-east-1 and have publish = true so that you can get the version (other than $LATEST) with aws_lambda_function.this.qualified_arn

brucedvgw on Jun 30, 2020

So the workaround I did was to ensure that aws_lambda_function had the publish = true set. This then enabled me to use aws_lambda_function.this.qualified_arn to get the arn with the version number.

Hope this helps someone!

brucedvgw on Jun 23, 2020