terraform do not get variable passed through modules - terraform

Question

I want to provision a simple terraform vpc and subnet.
I created a module and declared all the variable required in the module variable.tf
and passed wrote all the needed values through terraform.tfvars
but when I run terraform apply I get a prompt to insert a value for avail_zone
main.tf
module "myapp-subnet" {
source = "./modules/subnet"
subnet_cidr_block = var.subnet_cidr_block
avail_zone = "us-east-1a"
env_prefix = "dev"
vpc_id = aws_vpc.myapp-vpc.id
default_route_table_id = aws_vpc.myapp-vpc.default_route_table_id
}
modules/subnet/main.tf
resource "aws_subnet" "myapp-subnet-1" {
vpc_id = var.vpc_id
cidr_block = var.subnet_cidr_block
availability_zone = var.avail_zone
tags = {
Name: "${var.env_prefix}-subnet-1"
}
}
resource "aws_internet_gateway" "myapp-igw"{
vpc_id = var.vpc_id
tags = {
Name: "${var.env_prefix}-igw"
}
}
# using existing route table
resource "aws_default_route_table" "default-rtb" {
default_route_table_id = var.default_route_table_id
route{
cidr_block = "0.0.0.0/10"
gateway_id = aws_internet_gateway.myapp-igw.id
}
tags = {
Name: "${var.env_prefix}-main-rtb"
}
}
module/subnet/variables.tf
variable vpc_cidr_blocks {}
variable subnet_cidr_block {}
variable avail_zone {}
variable env_prefix{}
variable vpc_id {}
variable default_route_table_id {}
terraform.tfvars
vpc_cidr_blocks = "xxxx"
subnet_cidr_block = "xxxx"
avail_zone = "xxxxxx"
env_prefix = "dev"
myip = "xxxxxxx"
instance_type="t2.micro"
public_key_location= "/home/xxxxxxxx/.ssh/id_rsa.pub"