Terraform doesn't add log group name on cloudwatch event target

Question

I create a rule in Cloudwatch and attach a log group as its target in Terraform.

resource "aws_cloudwatch_event_target" "trigger_glue_job_lambda" {
  rule = "${aws_cloudwatch_event_rule.crawler.name}"
  target_id = "SendToLambda"
  arn = "${aws_lambda_function.trigger_glue_job.arn}"
}

resource "aws_cloudwatch_event_target" "log_glue_crawler_result" {
  rule = "${aws_cloudwatch_event_rule.crawler.name}"
  target_id = "LogCrawler"
  arn = "${aws_cloudwatch_log_group.grue_crawler_log_group.arn}"
}

resource "aws_cloudwatch_log_group" "grue_crawler_log_group" {
  name = "crawler_log"
  tags = {
    Application = "reddit_movies"
  }
}

You see the above configuration includes a log group resource definition and two event target, one for log group the other is for triggering a lambda. Below is the screenshot of this configuration in aws cloudwatch rule console.

You see the target in the bottom of the screenshot shows lambda correctly but it doesn't show the name of the log group I created. Instead, it shows a * for the log group name. I wonder what wrong with my configuration.

Answer 1

After checking the value of the arn attribute of cloudwatch log group, for some reason it is appending an asterisk at the end in this format format arn:aws:logs:eu-west-1:12345678912:log-group:crawler_log:*
Change your code like this to remove the last 2 characters:

resource "aws_cloudwatch_event_target" "log_glue_crawler_result" {
  rule = "${aws_cloudwatch_event_rule.crawler.name}"  
  target_id = "LogCrawler"
  arn = "${substr(aws_cloudwatch_log_group.grue_crawler_log_group.arn,0,length(aws_cloudwatch_log_group.grue_crawler_log_group.arn) - 2)}"
}