Terraform: Use list of map in module

[JonCubed]

Not sure if this is a bug report or feature request.

I would like to use aws_dynamodb_table in a module and pass in a list of literal attribute maps. I can pass the list of literal maps but I can't figure out how to assign it to the attribute property.

_./modules/table.tf_

resource "aws_dynamodb_table" "basic_dynamodb_table" {
    name                = "${var.table_name}"
    read_capacity       = "${var.read_capacity}"
    write_capacity      = "${var.write_capacity}"
    hash_key            = "${var.primary_key}"

    attribute {
        name            = "${var.primary_key}"
        type            = "${var.primary_key_type}"
    }

    attribute = "${var.attribute}"
}

variable "table_name" {}

variable "read_capacity" {
    default     = "1"
}

variable "write_capacity" {
    default     = "1"
}

variable "primary_key" {}

variable "primary_key_type" {}

variable "attribute" {
    default = []
    description = "List of defined attributes, map of { name, type }"
    type = "list"
}

_./dynamo.tf_

module "basic_table" {
    source              = "./modules/table"

    table_name          = "test-table"
    primary_key         = "Id"
    primary_key_type    = "S"

    attribute {
        name = "SecondaryId"
        type = "S"
    }

    attribute {
        name = "Type"
        type = "N"
    }
}

if I output attribute variable it show it as

attributes = [
    {
        name = SecondaryId,
        type = S
    },
    {
        name = Type,
        type = N
    }
]

however when I run terraform get it get Error loading .terraform\modules\93790fb028cae1e6f9168662d159650c\table.tf: Error reading config for aws_dynamodb_table[basic_dynamodb_table]: At 25:17: unknown slice type: *ast.LiteralType

Version:
Terraform v0.8.6

OS:
Windows 10 Home (Build: 14393.693)

[thomaschaaf]

I have the exact same problem but with the aws_elastic_beanstalk_environment resource where I am trying to set the setting parameter with a variable list. (0.9.0-beta2)

This doesn't work:

variable "settings" {
  type = "list"
  default = [
    {
      namespace = "aws:elasticbeanstalk:application:environment"
      name      = "B"
      value     = "true"
    },
    {
      namespace = "aws:elasticbeanstalk:application:environment"
      name      = "A"
      value     = "true"
    }
  ]
}

resource "aws_elastic_beanstalk_environment" "application" {
  name          = "${var.name}-application"
  application   = "${aws_elastic_beanstalk_application.application.name}"
  template_name = "${aws_elastic_beanstalk_configuration_template.application.name}"
  tier          = "WebServer"
  setting = "${var.settings}"
...
}

However setting it directly works:

resource "aws_elastic_beanstalk_environment" "application" {
  name          = "${var.name}-application"
  application   = "${aws_elastic_beanstalk_application.application.name}"
  template_name = "${aws_elastic_beanstalk_configuration_template.application.name}"
  tier          = "WebServer"
setting = [
    {
      namespace = "aws:elasticbeanstalk:application:environment"
      name      = "B"
      value     = "true"
    },
    {
      namespace = "aws:elasticbeanstalk:application:environment"
      name      = "A"
      value     = "true"
    }
  ]
...
}

Error reading config for aws_elastic_beanstalk_environment[application]: At 376:13: unknown slice type: *ast.LiteralType

[Puneeth-n]

Any update on this? I am facing the same issue.

[codevbus]

I'd like to see an update on this issue as well.

I think this also speaks to a fairly sizable gap in documentation around "module-izing" resources with variable-length attribute mappings. There seems to be no canonically established way to write a module such that you can easily accept different end-user use-cases.

[aavileli]

we should have the attribute added like a resource to dynamo-db just like we have for security groups with rules. Dynamo-db allows adding a table with only primary key or partition with defaults and then changing them.

[richardgregory]

I'm facing the same problem as @thomaschaaf. I've created a module for our beanstalk configuration and would like to pass in application environment settings, but running into this issue. Is there any update, or another way of doing this? thanks

[ciaranarcher]

Same issue here.

[sbaum1994]

Hi I'm not sure because I only did a terraform plan, but I think this might actually work if you just add brackets in with the list. Terraform expects lists to be passed bracketed like this ["${var.settings}"] Thought I'd post in case it fixes the issue, example -

variable "settings" {
  type = "list"
  default = [
    {
      namespace = "aws:elasticbeanstalk:application:environment"
      name      = "B"
      value     = "true"
    },
    {
      namespace = "aws:elasticbeanstalk:application:environment"
      name      = "A"
      value     = "true"
    }
  ]
}

resource "aws_elastic_beanstalk_environment" "application" {
  name          = "..."
  application   = "..."
  template_name = "..."
  tier          = "..."
  setting = ["${var.settings}"]
}

[vpal]

@sbaum1994's example seems to be working, there is one issue though.
When one writes
setting = ["${var.settings}"]
in the resource and the list is empty like

variable "settings" {
  type = "list"
  default = []
}

The following error is displayed:

1 error(s) occurred:

* module.elastic_beanstalk_environment.aws_elastic_beanstalk_environment.elastic_beanstalk_environment: setting.46: expected object, got invalid

Writing
setting = []
in the resource works though.
Seems like a bug with passing empty lists.

[Puneeth-n]

@vpal @sbaum1994 how do you look up the values? I seem to get an error: lookup: argument 1 should be type map, got type string

Update
Figured it out. :) Instead of using element parse the list using count.index

[vpal]

@Puneeth-n can you please give an example how you solved it, thanks.

[Puneeth-n]

* calling the module*

module "my-awesome-alb" {
    source = "../terraform_modules/my-alb-module"
    .
    .
    .
    listeners = [
        {
            port = 443
            certificate = "${data.aws_acm_certificate.wildcardDotComtravoDotCom.arn}"
        },
        {
            port = 444
            certificate = "${data.aws_acm_certificate.wildcardDotComtravoDotCom.arn}"
        }
    ]
    .
    .
    .
}

* Inside the module*

resource "aws_alb_listener" "listener" {
  count = "${length(var.listeners)}"

  load_balancer_arn = "${aws_alb.alb.arn}"
# access list via index and not via element
  port              = "${lookup(var.listeners[count.index], "port")}"
  protocol          = "HTTPS"
  ssl_policy        = "ELBSecurityPolicy-2016-08"
  certificate_arn   = "${lookup(var.listeners[count.index], "certificate")}"

  default_action {
    target_group_arn = "${element(aws_alb_target_group.dummy.*.arn, count.index)}"
    type             = "forward"
  }
}

[chanind]

@sbaum1994's solution doesn't work for me. It works if I write out settings explicitly inline like:

setting = [
  {...},
  {...}
]

but when I try to use a variable I get the following error:
root.setting[0]: not an object type for map (*ast.LiteralType)
I also get the same error when trying to use locals

Maybe there was a regression in a recent version of terraform?

update
I figured it out after finding this issue: https://github.com/terraform-providers/terraform-provider-aws/issues/3558. It turns out you need to put the setting = ["..."] statement above all other setting statements 🤷‍♂️

[bcarpio]

This bug report is addressing two different issues. The OP incorrectly described how aws_dynamodb_table works, attribute is a a "nested field" not a simple argument that takes a list such as settings in aws_elastic_beanstalk_environment.

If nested fields supported count like resources do this issue could be resolved actually. How should we go about submitting a feature request for count to be added to nested fields?

This would solve for more than just attribute but also global_secondary_index.

[bcarpio]

Looks like there is a feature request open for this already #7034

[apparentlymart]

Hi all!

Some outdated labelling on this issue caused me to miss it on the first pass of updating issues but indeed @bcarpio is right that this is covering the same problem as #7034, which has now been closed due to the new feature that will address it being merged in to master in preparation for the forthcoming v0.12.0 release. I left a comment over there showing how the new construct can be used.

Since there's a change already merged, I'm going to close this out. Sorry for the silence here!

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