While I am using terraform to create vpc flow log module to s3 bucket then its throwing errors like:
An argument named "flow_log_destination_type" is not expected here. An argument named "flow_log_destination_arn" is not expected here. In the Terraform docs, I can see the details to be filled like log_destination_type & log_destination_arn, and I found some docs on GitHub that exactly says the same code but while trying it's not working for me
The following error produced:
Error: Unsupported argument on main.tf line 52, in module "vpc_with_flow_logs_s3_bucket": 52: flow_log_destination_type = "s3" An argument named "flow_log_destination_type" is not expected here. Error: Unsupported argument on main.tf line 53, in module "vpc_with_flow_logs_s3_bucket": 53: flow_log_destination_arn = "${aws_s3_bucket.terra-test2-lifecycle.arn}" An argument named "flow_log_destination_arn" is not expected here. Error: Unsupported argument on main.tf line 55, in module "vpc_with_flow_logs_s3_bucket": 55: vpc_flow_log_tags = { An argument named "vpc_flow_log_tags" is not expected here. Where I am doing wrong?
module "vpc" { source = "terraform-aws-modules/vpc/aws" version = "2.33.0" # Interpolated from the workspace name = "${terraform.workspace}" cidr = var.vpc_cidr azs = var.vpc_azs private_subnets = var.vpc_private_subnets public_subnets = var.vpc_public_subnets enable_nat_gateway = var.vpc_enable_nat_gw single_nat_gateway = var.vpc_single_nat_gw public_subnet_tags = { Name = "${terraform.workspace}-public" } private_subnet_tags = { Name = "${terraform.workspace}-private" } tags = { Name = "${terraform.workspace}" } vpc_tags = { owner = "PEDevOps" environment = "${terraform.workspace}" version = "0.0.1" managedby = "Terraform" } } module "vpc_with_flow_logs_s3_bucket" { source = "../../" log_destination_type = "s3" log_destination_arn = "${aws_s3_bucket.terra-test2-lifecycle.arn}" vpc_flow_log_tags = { Name = "vpc-flow-logs-s3-bucket" } } resource "aws_s3_bucket" "terra-test-lifecycle" { bucket = "terra-test-lifecycle" acl = "private" lifecycle_rule { id = "log" enabled = true prefix = "log/" tags = { "rule" = "log" "autoclean" = "true" } transition { days = 30 storage_class = "STANDARD_IA" # or "ONEZONE_IA" } expiration { days = 60 } } lifecycle_rule { id = "tmp" prefix = "tmp/" enabled = true expiration { date = "2020-06-06" } } } Why does terraform fail with An argument named "flow_log_destination_type" is not expected here?
3 Answers
The module at "../../" does not declare any of the log_destination_type, log_destination_arn, or vpc_flow_log_tags variables and Terraform considers it an error to assign to undeclared variables in a module block like this:
module "vpc_with_flow_logs_s3_bucket" { source = "../../" log_destination_type = "s3" log_destination_arn = "${flow_log_destination_arn}" vpc_flow_log_tags = { Name = "vpc-flow-logs-s3-bucket" } } It's most likely that "../../" is the wrong source path for the vpc_with_flow_logs_s3_bucket module and you should fix that. If you are in the source path for the module where this module block is declared and you run cd ../../, do you end up in the directory with the vpc_with_flow_logs_s3_bucket Terraform code? If not, then source is set incorrectly and you need to fix it.
If "../../" is the correct path, then you should add the missing variable declarations.
variable "log_destination_type" { type = string } variable "log_destination_arb" { type = string } variable "vpc_flow_log_tags" { type = map(string) } This error occurs if you are passing a variable that module is not expecting.
For e.g.
module "vpc_with_flow_logs_s3_bucket" { source = "../../" log_destination_type = "s3" log_destination_arn = "${flow_log_destination_arn}" vpc_flow_log_tags = { Name = "vpc-flow-logs-s3-bucket" } } If you specify this it will throw an error if the variable flow_log_destination_arn is defined in main.tf and not in variables.tf
source: ../../vpc_with_flow_logs_s3_bucket/main.tf
resource "aws_flow_log" "example" { iam_role_arn = "${aws_iam_role.example.arn}" log_destination = "${aws_cloudwatch_log_group.example.arn}" traffic_type = "ALL" vpc_id = "${aws_vpc.example.id}" } I'll share another possible reason to this error.
Writing configuration block like this:
scaling_config = { desired_size = 2 max_size = 2 min_size = 2 } Instead of (Notice the = Equal Sign):
scaling_config { desired_size = 2 max_size = 2 min_size = 2 } Will give an error of An argument named "scaling_config" is not expected here.
(*) Notice that after the change, if the block type is really not supported the error title will be change from:
Error: Unsupported argument To:
Error: Unsupported block type With error message of:
Blocks of type "scaling_config" are not expected here. 
