try() to generate output.ses_smtp_password_v4

[rsrchboy]

In module upgrades, I'm seeing errors like this:

Error: Invalid function argument

on .terraform/modules/user/outputs.tf line 29, in output "ses_smtp_password_v4":
29:   value       = join("", aws_iam_access_key.default.*.ses_smtp_password_v4)
    |----------------
    | aws_iam_access_key.default is tuple with 1 element

Invalid value for "lists" parameter: element 0 is null; cannot concatenate
null values.

This change wraps the join() with a try(..., null), causing null
to be returned as a fallback on error.

[SweetOps]

It is very weird... all outputs in this module use construction join("", something), but you've got error only in one place. I suppose that need to bump version of aws provider and it'll fix issue permamently

https://github.com/cloudposse/terraform-aws-iam-system-user/blob/master/versions.tf#L5

[kristjankullerkann]

I seem to be hitting this very same issue.
In more details:

• I am using cloudposse/terraform-aws-s3-bucket which has a dependency to cloudposse/terraform-aws-iam-s3-user which has dependency to this module.
• I have something like this in my provider configuration (so it should be quite new):

provider "aws" {
  version = "~> 3.7.0"
  region = var.region
  profile = var.profile
  shared_credentials_file = var.shared_credentials_file
}

• terraform is 0.13.3
• interesting to note that this happens only on upgrade, because creating a new s3 bucket doesn't introduce this error.

[kristjankullerkann]

I think I have managed to identify the issue and resolve it.

In the older module, we can find from state file something like:

{
  "module": "module.s3_bucket.module.s3_user.module.s3_user",
  "mode": "managed",
  "type": "aws_iam_access_key",
  "name": "default",
  "provider": "provider[\"registry.terraform.io/-/aws\"]",
  "instances": [
    {
      "index_key": 0,
      "schema_version": 0,
      "attributes_flat": {
        "id": "someid",
        "secret": "somesecret",
        "ses_smtp_password": "somesecret",
        "status": "Active",
        "user": "user"
      }
    }
  ]
}

In the newer module, we can find something like:

{
  "module": "module.s3_bucket.module.s3_user.module.s3_user",
  "mode": "managed",
  "type": "aws_iam_access_key",
  "name": "default",
  "provider": "provider[\"registry.terraform.io/-/aws\"]",
  "instances": [
    {
      "index_key": 0,
      "schema_version": 0,
      "attributes_flat": {
        "id": "someid",
        "secret": "somesecret",
        "ses_smtp_password_v4": "somesecret",
        "status": "Active",
        "user": "user"
      }
    }
  ]
}

As you can see the key named ses_smtp_password has changed to ses_smtp_password_v4.

After modifying key name, I managed to successfully upgrade the module and its state.

Workflow is as follows:

1. pull the state with terraform state pull > state.out.
2. modify state.out file as described above.
3. push state with terraform state push -force state.out.
4. upgrade module.