Part 3 - Create an RDS DB instance
Create a new file rds.tf which we will add all of our RDS configuration to.
Create subnets in each availability zone for RDS, each with address blocks within the VPC:
resource "aws_subnet" "rds" {
count = "${length(data.aws_availability_zones.available.names)}"
vpc_id = "${aws_vpc.vpc.id}"
cidr_block = "10.0.${length(data.aws_availability_zones.available.names) + count.index}.0/24"
map_public_ip_on_launch = true
availability_zone = "${element(data.aws_availability_zones.available.names, count.index)}"
tags {
Name = "rds-${element(data.aws_availability_zones.available.names, count.index)}"
}
}Create a subnet group with all of our RDS subnets. The group will be applied to the database instance:
resource "aws_db_subnet_group" "default" {
name = "${var.rds_instance_identifier}-subnet-group"
description = "Terraform example RDS subnet group"
subnet_ids = ["${aws_subnet.rds.*.id}"]
}Create a RDS security group in the VPC which our database will belong to:
resource "aws_security_group" "rds" {
name = "terraform_rds_security_group"
description = "Terraform example RDS MySQL server"
vpc_id = "${aws_vpc.vpc.id}"
# Keep the instance private by only allowing traffic from the web server.
ingress {
from_port = 3306
to_port = 3306
protocol = "tcp"
security_groups = ["${aws_security_group.default.id}"]
}
# Allow all outbound traffic.
egress {
from_port = 0
to_port = 0
protocol = "-1"
cidr_blocks = ["0.0.0.0/0"]
}
tags {
Name = "terraform-example-rds-security-group"
}
}Create a RDS MySQL database instance in the VPC with our RDS subnet group and security group:
resource "aws_db_instance" "default" {
identifier = "${var.rds_instance_identifier}"
allocated_storage = 5
engine = "mysql"
engine_version = "5.6.35"
instance_class = "db.t2.micro"
name = "${var.database_name}"
username = "${var.database_user}"
password = "${var.database_password}"
db_subnet_group_name = "${aws_db_subnet_group.default.id}"
vpc_security_group_ids = ["${aws_security_group.rds.id}"]
skip_final_snapshot = true
final_snapshot_identifier = "Ignore"
}Manage the MySQL configuration by creating a parameter group:
resource "aws_db_parameter_group" "default" {
name = "${var.rds_instance_identifier}-param-group"
description = "Terraform example parameter group for mysql5.6"
family = "mysql5.6"
parameter {
name = "character_set_server"
value = "utf8"
}
parameter {
name = "character_set_client"
value = "utf8"
}
}Finally let's define new variables that we have introduced in configuration blocks during this section.
Add the following to variables.tf:
variable "rds_instance_identifier" {}
variable "database_name" {}
variable "database_password" {}
variable "database_user" {}Assign the variable values in terraform.tfvars, excluding the password variable:
rds_instance_identifier = "terraform-mysql"
database_name = "terraform_test_db"
database_user = "terraform"Assign the password variable in our user.tfvars file which should be ignored from version control. Give this property a random password. It will be the MySQL password for the Terraform user account used by the web application.
database_password = "some-random-password"We can now try another plan:
$ terraform plan -var-file="user.tfvars"
Terraform will perform the following actions:
+ aws_db_instance.default
+ aws_db_parameter_group.default
+ aws_db_subnet_group.default
+ aws_security_group.rds
+ aws_subnet.rds[0]
+ aws_subnet.rds[1]
+ aws_subnet.rds[2]
Plan: 7 to add, 0 to change, 0 to destroy.It's time to review the plan and apply our changes again before we move on!
$ terraform apply -var-file="user.tfvars"
Apply complete! Resources: 7 added, 0 changed, 0 destroyed.You can find all the source code for this part of the lab here in GitHub.