Argument or block definition required Terraform - Error - linux

Question

I have autoscaling group and I need to create an application load balancer for accessing the application this is my two code for autoscaling and application load balancer but I get this issue
autoscaling group
resource "aws_launch_configuration" "OS-Type"{
name_prefix = "OS-Type"
image_id = "ami-0996d3051b72b5b2c"
instance_type = "t2.micro"
lifecycle {
create_before_destroy = true
}
}
resource "aws_autoscaling_group" "Dynamic-IN"{
name = "Dynamic-EC2-instance"
min_size = 1
max_size = 4
desired_capacity = 2
health_check_type = "ELB"
launch_configuration = aws_launch_configuration.OS-Type.name
vpc_zone_identifier = [aws_subnet.P-AV1.id, aws_subnet.P-AV2.id]
target_group_arns="aws_lb.App-lb.name"
lifecycle {
create_before_destroy = true
}
}
Application load balancer
resource "aws_lb_target_group" "Target-group"{
name = "Target-group"
port = 80
protocol = "HTTP"
vpc_id = aws_vpc.main.id
}
resource "aws_lb" "App-lb"{
name = "Application-load-balancer"
load_balancer_type = "application"
subnets = [aws_subnet.P-AV1.id , aws_subnet.P-AV2.id]
internal = false
}
resource "aws_autoscaling_attachment" "TG-attach" {
autoscaling_group_name = aws_autoscaling_group.Dynamic-IN.id
alb_target_group_arn = aws_lb_target_group.Target-group.arn
}
I get this error
Error: Argument or block definition required
on autoscalling-group.tf line 20, in resource "aws_autoscaling_group" "Dynamic-IN":
20: target_group.arns="aws_lb.App-lb.name"
An argument or block definition is required here. To set an argument, use the
equals sign "=" to introduce the argument value.
I have tried
I have tried aws_lb.App-lb.arns for the target group alos but not working in the both ways

Answer 1

Yes like you suspect there should not quotes there:
target_group_arns="aws_lb.App-lb.name"
and that 'target_group_arns' is a set not a single item: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/autoscaling_group#target_group_arns
target_group_arns (Optional) A set of aws_alb_target_group ARNs, for use with Application or Network Load Balancing.
Your code should probably be something like:
resource "aws_autoscaling_group" "Dynamic-IN" {
name = "Dynamic-EC2-instance"
min_size = 1
max_size = 4
desired_capacity = 2
health_check_type = "ELB"
launch_configuration = aws_launch_configuration.OS-Type.name
vpc_zone_identifier = [ aws_subnet.P-AV1.id, aws_subnet.P-AV2.id ]
target_group_arns = [ aws_lb_target_group.Target-group.arn ]
lifecycle {
create_before_destroy = true
}
}