Terraform-provider-aws: Cannot Select RDS Engine Version The Contains Alpha Characters

[hashibot]

_This issue was originally opened by @jflammia as hashicorp/terraform#15259. It was migrated here as part of the provider split. The original body of the issue is below._

---

Terraform Version

Terraform v0.9.6

Terraform Configuration Files

database_allocated_storage = "240"
database_storage_type = "standard"
database_engine = "postgres"
database_engine_version = "9.6.2-R1"
database_instance_class = "db.t2.large"
database_username = "user"
database_password = "password"

variable "database_allocated_storage" {
  type        = "string"
  description = "The allocated storage in gigabytes."
}

variable "database_storage_type" {
  type        = "string"
  description = "The AWS volume type.  Options: 'standard', 'gp2' (General Purpose SSD), or 'io1' (Provisioned IOPS)."
}

variable "database_instance_class" {
  type        = "string"
  description = "The instance type of the RDS instance."
}

variable "database_engine" {
  type        = "string"
  description = "The database engine to use."
}

variable "database_engine_version" {
  type        = "string"
  description = "The engine version to use."
}

variable "database_username" {
  type        = "string"
  description = "Username for the master DB user."
}

variable "database_password" {
  type        = "string"
  description = "Password for the master DB user."
}

resource "aws_db_instance" "tv" {
  identifier = "tv-database"

  vpc_security_group_ids = ["${data.terraform_remote_state.db_sg.sg_id}"]
  db_subnet_group_name   = "tv_database_sng"
  publicly_accessible    = false

  allocated_storage = "${var.database_allocated_storage}"
  storage_type      = "${var.database_storage_type}"
  instance_class    = "${var.database_instance_class}"

  engine         = "${var.database_engine}"
  engine_version = "${var.database_engine_version}"

  username = "${var.database_username}"
  password = "${var.database_password}"

  tags {
    Name               = "TV-Database"
    ManagedByTerraform = "true"
    Environment        = "${terraform.env}"
  }
}

Debug Output

Error applying plan:

1 error(s) occurred:

* aws_db_instance.tv: 1 error(s) occurred:

* aws_db_instance.tv: Error creating DB Instance: InvalidParameterCombination: Cannot find version 9.6.2-r1 for postgres
    status code: 400, request id: 

Expected Behavior

Should be able to select any of the engine versions that AWS makes available for AWS RDS, specificially PostgreSQL

Actual Behavior

Terraform runs a tolower() method on the argument passed in to the AWS API. In other words, "9.6.2-R1" gets transmitted as "9.6.2-r1". AWS cannot locate the correct engine version since it seems to be case sensitive.

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. Create a aws_db_instance resource with the engine_version set to a value that has an uppercase alpha character in it
2. The plan output has the engine_version string represented correctly. However, the terraform apply transmits it differently.

[pavgup]

Definitely running into this as well. Provisioning postgresql instances is a bit weird since all of the versions include '-R1' in their name.

[suneeta-mall]

Turns out R1 is not needed in engine version afterall. Just drop the R1 from the engine version and it works fine. So for 9.6.3-R1 just this would work engine_version = "9.6.3"

[nywilken]

@suneeta-mall thanks for the help on this old issue. I am going to close this as the solution is to specify the version as documented at https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_PostgreSQL.html#PostgreSQL.Concepts.General.DBVersions

Sorry for any confusion or problems this may have presented for users.

[hashibot[bot]]

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 feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!