Terraform Script to Automate Infrastructure

Hello Guys,

In the last blog about Terraform we talked about how Terraform works and we wrote a simple script to fire an EC2 instance. In this blog , we will take it a step further and write a Terraform script to achieve the following goals:

provider "Aws" {
    profile = "myprofile"
    region = "us-east-1"
}

resource "aws_vpc" "demo-vpc" {
    cider_block = "10.0.0.0/16"
    }

resource "aws_subnet" "public-subnet"{
    vpc_id = ["${aws_vpc.demo-vpc.id}"]
    cider_block = "10.0.1.0/24"

    tags = {
        Name = "public-subnet"
    }
}
resource "aws_subnet" "public-subnet2" {
    vpc_id = ["${aws_vpc.demo-vpc.id}"]
    cider_block = "10.0.2.0/24"

    tags = {
        Name = "public-subnet2"
    }
}

resource  "Aws_internet_gateway" "vpc-igw" {
    vpc_id = ["${aws_vpc.demo-vpc.id}"]
}

resource  "aws_network_acl" "public-nacl" {
    vpc_id = "${aws_vpc.demo-vpc.id}"
    subnet_ids = ["${aws_subnet.public-subnet.id}", "${aws_subnet.public-subnet2.id}"]

    ingress {
        rule_no = "100"
        protocol = "TCP"
        from_port = "80"
        to_port = "80"
        action = "allow"
        cider_block = "0.0.0.0/0"
            }

       ingress {
        rule_no = "200"
        protocol = "TCP"
        from_port = "1024"
        to_port = "65535"
        action = "allow"
        cider_block = "0.0.0.0/0"
       }

       ingress {
        rule_no = "300"
        protocol = "TCP"
        from_port = "22"
        to_port = "22"
        action = "allow"
        cider_block = "0.0.0.0/0"
       }

    egress {
        rule_no = "100"
        protocol = "TCP"
        from_port = "80"
        to_port = "80"
        action = "allow"
        cider_block = "0.0.0.0/0"
    }

    egress {
         rule_no = "200"
        protocol = "TCP"
        from_port = "1024"
        to_port = "65535"
        action = "allow"
        cider_block = "0.0.0.0/0"
    }
     
    egress {
        rule_no = "300"
        protocol = "TCP"
        from_port = "22"
        to_port = "22"
        action = "allow"
        cider_block = "0.0.0.0/0"
    }

}

resource "aws_security_group" "my-sg"{
      Name = "my-sg"
      description = "Security group for webserver"
      vpc_id = "${aws_vpc.demo-vpc.id}"

      ingress {
        protocol = "TCP"  
        from_port = "80"
        to_port = "80"
        cider_block = "0.0.0.0/0"
        
      }  

      ingress {
        protocol = "TCP"  
        from_port = "22"
        to_port = "22"
        cider_block = "0.0.0.0/0"
      }  
}

resource "aws_security_group" "mysgdb"{
      Name = "mysgdb"
      description = "Security group for DB"
      vpc_id = "${aws_vpc.demo-vpc.id}"


      ingress {
        protocol = "TCP"  
        from_port = "3306"
        to_port = "3306"
        cider_block = "0.0.0.0/0"
        
      }  

      
}

resource "aws_instance" "webserver1"{
    ami = "ami-0cff7528ff583bf9a"
    instance_type = "t2.micro"
    vpc_security_group_ids = ["${aws_security_group.my-sg.id}"] 
    key_name = "gl"
    subnet_id = ["${aws_subnet.public-subnet.id}"]
     
}
 
 resource "aws_instance" "webserver2" {
    ami = "ami-0cff7528ff583bf9a"
    instance_type = "t2.micro"
    vpc_security_group_ids = ["${aws_security_group.my-sg.id}"] 
    key_name = "gl"
    subnet_id = ["${aws_subnet.public-subnet2.id}"]
     
}
resource "aws_alb" "webalb" {
    name = "webalb"
    internal = "false"
    load_balancer_type = "application"
    subnets = ["${aws_subnet.public-subnet.id}", "${aws_subnet.public-subnet2.id}"]  
    vpc_security_group_ids = ["${aws_security_group.my-sg.id}"]      
        
}

resource "aws_alb_listener" "webalb-list" {
    load_balancer_arn = ["${aws_lb.webalb.arn}"]
    port = "80"
    protocol = "HTTP"
    default_action {
      type = "forward"
      target_group_arn = ["${aws_lb_target_group.web-tg.id}"]
    }
     
}

resource "aws_alb_target_group" "web-tg" {
    name = "web-tg"
    port = "80"
    protocol = "HTTP"
    vpc_id = ["${aws_vpc.demo-vpc.id}"]

}
  
resource "aws_alb_target_group_attachment" "web-tg-attach" {
    target_group_arn = ["${aws_alb_target_group.web-tg.arn}"]
    target_id = ["${aws_instance.webserver1.id}"]
    port = "80"

}
resource "aws_alb_target_group_attachment" "web-tg-attach2" {
    target_group_arn = ["${aws_alb_target_group.web-tg.arn}"]
    target_id = ["${aws_instance.webserver2.id}"]
    port = "80"
    
}

resource "aws_db_subnet_group" "mysql-subnet-group" {
  name = "mysql-subnet-group"
  subnet_ids = ["${aws_subnet.public-subnet.id}" , "${aws_subnet.public-subnet2.id }" ]
}


resource "aws_db_instance" "mydb" {
    allocated_storage = "20"
    storage_type = "gp2"
    engine = "mysql"
    engine_version = "8.0.29"
    instance_class = "db.t2.micro"
    name = "mydb"
    username = "mysql-user"
    password = "mysql-password"
    db_subnet_group_name = "${aws_db_subnet_group.mysql-subnet-group.id}"
    vpc_security_group_ids = ["${aws_security_group.my-sg-db.id}"]
}

Once we run this code , we will provision an entire set of infrastructure in cloud by just writing the code and without having to touch the console. We can reuse this as many times as we want.