Terraform - what is the URI to invoke lambda via alias? - aws-lambda

Question

Question
To invoke a Lambda from API GW, invoke_arn can be used for aws_lambda_function resources.
invoke_arn - The ARN to be used for invoking Lambda Function from API Gateway.
resource "aws_api_gateway_integration" "videos" {
rest_api_id = "${aws_api_gateway_rest_api.24_hour_video.id}"
resource_id = "${aws_api_gateway_method.videos_get.resource_id}"
http_method = "${aws_api_gateway_method.videos_get.http_method}"
integration_http_method = "GET"
type = "AWS_PROXY" # Lambda Proxy
uri = "${aws_lambda_function.list_videos.invoke_arn}"
}
What is to set in uri to invoke the same lambda via an alias?
resource "aws_lambda_alias" "lambda_alias_list_videos" {
name = "get_video_list"
description = "Alias to lambda_list_videos"
function_name = "${aws_lambda_function.list_videos.arn}"
function_version = "$LATEST"
}

Answer 1

The aws_lambda_alias resource creates an alias which points to a specific version of a Lambda function. The alias itself is not invocable.
Instead you should create an aws_lambda_function Data Source that points to the aliased version, and use its invoke_arn property. You can use the qualifier argument in an aws_lambda_function to specify either a version or an alias name (see AWS Lambda Invoke Docs for more info).
Your example shows you have already created an alias named get_video_list, which points to the $LATEST version. You need to create a new Data Source that points to this alias:
data "aws_lambda_function" "my_function_get_video_list" {
function_name = "your-function-name"
qualifier = "get_video_list"
}
You can now get the invocation ARN of the aliased function:
${aws_lambda_function.my_function.get_video_list.invoke_arn}

Answer 2

aws_lambda_alias resource has invoke_arn attribute (see docs) which is designed for API Gateway. For example:
resource "aws_lambda_alias" "api_function_alias_live" {
name = "live"
function_name = aws_lambda_function.api_function.function_name
function_version = "1"
}
resource "aws_api_gateway_integration" "proxy_integration" {
rest_api_id = aws_api_gateway_rest_api.api_gateway.id
resource_id = aws_api_gateway_resource.proxy_resource.id
http_method = aws_api_gateway_method.proxy_method.http_method
integration_http_method = "POST"
type = "AWS_PROXY"
uri = aws_lambda_alias.api_function_alias_live.invoke_arn
}