Terraform count within for_each loop - google-cloud-platform

Question

I'm trying to create GCP SQL DBs by iterating a list of string using Terraform's for_each and count parameter and the other loop is for the map keys (maindb & replicadb).
Unfortunately, I get the error that appears below.
Is it possible to do this is Terraform?
variables.tf
variable "sql_var" {
default = {
"maindb" = {
"db_list" = ["firstdb", "secondsdb", "thirddb"],
"disk_size" = "20",
},
"replicadb" = {
"db_list" = ["firstdb"],
"disk_size" = "",
}
}
}
main.tf
resource "google_sql_database_instance" "master_sql_instance" {
...
}
resource "google_sql_database" "database" {
for_each = var.sql_var
name = "${element(each.value.db_list, count.index)}"
instance = "${google_sql_database_instance.master_sql_instance[each.key].name}"
count = "${length(each.value.db_list)}"
}
Error Message
Error: Invalid combination of "count" and "for_each"
on ../main.tf line 43, in resource
"google_sql_database" "database": 43: for_each =
var.sql_var
The "count" and "for_each" meta-arguments are mutually-exclusive, only
one should be used to be explicit about the number of resources to be
created.

Answer 1

What the error message tells you is that you cannot use count and for_each together. It looks like you are trying to create 3 main databases and 1 replica database am I correct? What I would do is create your 2 master instances and then transform your map variable to create the databases.
terraform {
required_version = ">=0.13.3"
required_providers {
google = ">=3.36.0"
}
}
variable "sql_instances" {
default = {
"main_instance" = {
"db_list" = ["first_db", "second_db", "third_db"],
"disk_size" = "20",
},
"replica_instance" = {
"db_list" = ["first_db"],
"disk_size" = "20",
}
}
}
locals {
databases = flatten([
for key, value in var.sql_instances : [
for item in value.db_list : {
name = item
instance = key
}
]
])
sql_databases = {
for item in local.databases :
uuid() => item
}
}
resource "google_sql_database_instance" "sql_instance" {
for_each = var.sql_instances
name = each.key
settings {
disk_size = each.value.disk_size
tier = "db-f1-micro"
}
}
resource "google_sql_database" "sql_database" {
for_each = local.sql_databases
name = each.value.name
instance = each.value.instance
depends_on = [
google_sql_database_instance.sql_instance,
]
}
Then, first run terraform apply -target=google_sql_database_instance.sql_instance and after this run terraform apply.