Terraform: Documentation issue in aws_lambda_function

[FransUrbo]

Terraform Version

0.7.13

Affected Resource(s)

• aws_lambda_function

Issue

The page https://www.terraform.io/docs/providers/aws/r/lambda_function.html#variables states:

variables - (Optional) A map that defines environment variables for the Lambda function.

But when creating a map

variable "something" {
  type = "map"
  default {
    something = "somethingelse"
  }
}

And use it as:

resource "aws_lambda_function" "something" {
  environment = "${var.something}"
}

I get:

  * aws_lambda_function.something: environment: should be a list

[FransUrbo]

Thinking about this a bit more, I think that TF is wrong in requiring it to be a list. A list don't have key/value (as in "variable name" and "variable value"), so the documentation is probably right, but the TF code is wrong.

[stack72]

Hi @FransUrbo

Apologies for the issue here - i am not quite sure why we have such a confusing message on this. From our nightly acceptance tests, I can see we have the following example:

resource "aws_lambda_function" "lambda_function_test" {
    filename = "test-fixtures/lambdatest.zip"
    function_name = "my-test-lambda-name"
    role = "${aws_iam_role.iam_for_lambda.arn}"
    handler = "exports.example"
    environment {
        variables = {
            foo = "bar"
        }
    }
}

If you can, give that a shot and see if that works out for you - if so, then i will change the documentation example to reflect this

Paul

[apparentlymart]

I think the confusing message here comes from how we represent nested blocks like that environment block. Inside the helper/schema system there's no support for a single nested block, so we usually represent it as either a set or list of nested blocks and then check in the code to make sure that this list/set only has one member. But if you give it something other than a list, it'd get caught up in the built-in validation logic in helper/schema, which is (I suspect) what is generating this generic error message.

To improve on this we'd probably need to give helper/schema itself some way to model these single nested block constructs, so that it can then give a more appropriate error message.

[FransUrbo]

Worked perfectly, thank you!

[stack72]

Hi @FransUrbo

Just opened https://github.com/hashicorp/terraform/pull/10490 to help address the example here

Thanks for letting me know

Paul

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