Error in Terraform v0.12.8: Inappropriate value for attribute "route_table_ids": element 0: string required.

[jalajarora]

Terraform Version

Terraform v0.12.8
+ provider.aws v2.15.0
+ provider.template v2.1.2

Terraform Configuration Files

resource "aws_vpc_endpoint" "s3" {
  vpc_id            = "${module.vpc.vpc_id}"
  service_name      = "com.amazonaws.eu-west-1.s3"
  vpc_endpoint_type = "Gateway"
  route_table_ids   = ["${module.vpc.private_route_table_ids}"]
}

When I use above I get below error on terraform plan

Debug Output

  on report_generator_s3.tf line 11, in resource "aws_vpc_endpoint" "s3":
  11:   route_table_ids   = ["${module.vpc.private_route_table_ids}"]

Inappropriate value for attribute "route_table_ids": element 0: string
required.

And, I tried doing below as well:

  vpc_id            = "${module.vpc.vpc_id}"
  service_name      = "com.amazonaws.eu-west-1.s3"
  vpc_endpoint_type = "Gateway"
  route_table_ids   = "${module.vpc.private_route_table_ids}"
}

I get the same error on terraform plan

Error: Incorrect attribute value type

  on report_generator_s3.tf line 11, in resource "aws_vpc_endpoint" "s3":
  11:   route_table_ids   = "${module.vpc.private_route_table_ids}"

Inappropriate value for attribute "route_table_ids": element 0: string
required.

Crash Output

Expected Behavior

Actual Behavior

Steps to Reproduce

Additional Context

References

[kmoe]

Thanks for the report, @jalajarora.

Since the value you want to interpolate, module.vpc.private_route_table_ids, is in another module, please include this module in your report, or use a variable to create a minimal reproduction case if it doesn't matter that it's from another module.

[jalajarora]

Hi @kmoe Thanks for your reply.
flatten function seems to resolve the issue.

  route_table_ids   = flatten(["${module.vpc.private_route_table_ids}"])

[kmoe]

That's great to hear. I don't know what the type of your module.vpc.private_route_table_ids variable is, but route_table_ids must be a set of strings, and it sounds like using flatten produced the correct type.

I'm going to close this issue now as this is not a bug in Terraform Core.

[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.