Using the VPC

Our EC2 module doesn't have the ability to be told what subnets (and therefore which VPC) to be created within. That means they'll be assigned to a subnet in the default VPC in our us-east-2 region.

We'll fix that by updating the ec2 module so it can be told which subnets to join.

File variables.tf

Add the following to file modules/ec2/variables.tf:

 1variable subnets {
 2  type = list(string)
 3  description = "valid subnets to assign to server"
 4}
 5 
 6variable security_groups {
 7  type = list(string)
 8  description = "security groups to assign to server"
 9  default = []
10}

File main.tf

We'll update file modules/ec2/main.tf to make use of the new variables.

We make use of the random_shuffle provider to get us a random subnet from given list of subnets we provide.

 1+resource "random_shuffle" "subnets" { 
 2+  input = var.subnets
 3+  result_count = 1
 4+} 
 5  
 6 resource "aws_instance" "cloudcasts_web" {
 7   ami           = var.instance_ami
 8   instance_type = var.instance_size
 9  
10   root_block_device {
11     volume_size = var.instance_root_device_size
12     volume_type = "gp3"
13   }
14  
15+  subnet_id = random_shuffle.subnets.result[0] 
16+  vpc_security_group_ids = var.security_groups 
17  
18   lifecycle {
19     create_before_destroy = true
20   }
21  
22   tags = {
23     Name        = "cloudcasts-${var.infra_env}-${var.infra_role}"
24     Role        = var.infra_role
25     Project     = "cloudcasts.io"
26     Environment = var.infra_env
27     ManagedBy   = "terraform"
28   }
29 }

File cloudcasts.tf

Finally, we can update the cloudcasts.tf file to say which subnets to create the ec2 instances into.

 1 module "ec2_app" {
 2   source = "./modules/ec2"
 3  
 4   infra_env = var.infra_env
 5   infra_role = "app"
 6   instance_size = "t3.small"
 7   instance_ami = data.aws_ami.app.id
 8+  subnets = keys(module.vpc.vpc_public_subnets) # Note: Public subnets 
 9+  # security_groups = [] # TODO: Create security groups
10+  # instance_root_device_size = 12 
11 }
12  
13 module "ec2_worker" {
14   source = "./modules/ec2"
15  
16   infra_env = var.infra_env
17   infra_role = "app"
18   instance_size = "t3.small"
19   instance_ami = data.aws_ami.app.id
20+  subnets = keys(module.vpc.vpc_private_subnets) # Note: Private subnets  
21+  # security_groups = [] # TODO: Create security groups
22+  # instance_root_device_size = 20 // 
23 }

We have a new provider plugin used (via the random_shuffle resource), so we need to init before planning/applying:

1terraform init
2terraform plan -var-file=variables.tfvars
3terraform apply -var-file=variables.tfvars