panic trying to use nested maps in 0.7_rc2

[pccowboy]

Terraform Version

dswift@bebox terraform (chore-121334261)*$ terraform --version
Terraform v0.7.0-rc2 (46a0709)

Affected Resource(s)

N/A

Terraform Configuration Files

dswift@bebox terraform (chore-121334261)*$ cat t/test.tf
variable db_replica_alarms {
    default = {
      "total" = {
         "count" = "2"
         "take" = "2"
      }
      "0" = {
        "0"="a"
        "1"="b"
        "desc" = "one desc"
      }
      "1" = {
        "2"="c"
        "3"="d"
        "desc" = "two desc"
      }
      "2" = {
        "4" = "e"
        "5"="f"
        "desc" = "three desc"
      }
      "desc" = {
        "0" = "one d"
        "1" = "two d"
        "2" = "tre d"
      }
    }
}

resource "aws_cloudwatch_metric_alarm" "replica_alarms" {
    count = "${element(var.db_replica_alarms["total"], 0)}"

    alarm_description = "${lookup(var.db_replica_alarms[count.index], "desc")}"
}

Debug Output

https://gist.github.com/pccowboy/c9d4e9f94ec404a718f745b2053351a5

Panic Output

https://gist.github.com/pccowboy/c9d4e9f94ec404a718f745b2053351a5

Expected Behavior

Trying to figure out how to access a variable in a nested map. I expected an error, due to the aws_cloudwatch_metric_alarm resource being incomplete.

Actual Behavior

crash

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. terraform plan t

Important Factoids

N/A

References

N/A

[pccowboy]

Prior to this crash, the config file looked like this:

variable db_replica_alarms {
    default = {
      "total" = {
         "count" = "2"
         "take" = "2"
      }
      "0" = {
        "0"="a"
        "1"="b"
        "desc" = "one desc"
      }
      "1" = {
        "2"="c"
        "3"="d"
        "desc" = "two desc"
      }
      "2" = {
        "4" = "e"
        "5"="f"
        "desc" = "three desc"
      }
      "desc" = {
        "0" = "one d"
        "1" = "two d"
        "2" = "tre d"
      }
    }
}

resource "aws_cloudwatch_metric_alarm" "replica_alarms" {
    count = "${lookup(var.db_replica_alarms["total"], "count")}"

    alarm_description = "${lookup(var.db_replica_alarms[count.index], "desc")}"
}

and gave this error:

dswift@bebox terraform (chore-121334261)*$ terraform plan t
provider.aws.region
  The region where AWS operations will take place. Examples
  are us-east-1, us-west-2, etc.

  Default: us-east-1
  Enter a value:

Error configuring: 1 error(s) occurred:

* At column 3, line 1: lookup: argument 1 should be type map, got type list in:

${lookup(var.db_replica_alarms["total"], "count")}

[jen20]

Thanks for the report, @pccowboy! I can reproduce this (though slightly differently) with the master branch and will investigate today.

[jen20]

Hi @pccowboy! I'll address the panic soon, but the correct way to do this is as follows:

variable "db_replica_alarms_totals" {
    type = "map"
    default = {
        count = "2"
        take = "2"
    }
}

variable "db_replica_alarms_settings" {
    type = "list"
    default = [
        {
            "0" = "a"
            "1" = "b"
            "desc" = "one desc"
        },
        {
            "0" = "c"
            "1" = "d"
            "desc" = "two desc"
        },
    ]
}

resource "aws_cloudwatch_metric_alarm" "replica_alarms" {
    count = "${var.db_replica_alarms_totals["count"]}"

    alarm_description = "${lookup(var.db_replica_alarms_settings[count.index], "desc")}"
}

[pccowboy]

@jen20 Thanks for the pointer, I am still wrapping my head around HCL and terraform. I had similar code working in 0.6.16, but in that version each map in db_replica_alarms_settings was a separate variable - one for description, one for action, etc. My old Perl habits were hoping to intermix objects in 0.7 a bit more than I maybe should hope for.

Looking forward to 0.7 GA, thanks again!

[jen20]

The panic is fixed by #7834. Thanks for reporting @pccowboy!

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.