Adding terraform files

Author: codeplusmath

alb.tf

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+# ALB(application Load Balancer Part)
+resource "aws_lb" "terra_alb" {
+    name = "terra-alb"
+    internal = false
+    load_balancer_type = "application"
+    security_groups = [aws_security_group.terra_alb_http.id]
+    subnets = [aws_subnet.autoscaling_ws_sub_1.id, aws_subnet.autoscaling_ws_sub_2.id]
+
+    tags = {
+        Name = "Terra ALB"
+    }
+}
+
+# ALB listener for forwarding http traffic
+resource "aws_lb_listener" "terra_alb_listener" {
+  load_balancer_arn = local.alb_arn
+  port              = "80"
+  protocol          = "HTTP"
+
+  default_action {
+    type             = "forward"
+    target_group_arn = aws_lb_target_group.terra_alb_target_grp.arn
+  }
+}

alb_sg.tf

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+# AWS security group for Application Load Balancer(ALB)
+resource "aws_security_group" "terra_alb_http" {
+    name = "terra_alb_http"
+    vpc_id = local.terra_vpc_id
+
+    ingress {
+      from_port = 80
+      to_port = 80
+      protocol = "tcp"
+      cidr_blocks = ["0.0.0.0/0"]
+    }
+
+    egress {
+      from_port = 0
+      to_port = 0
+      protocol = "-1"
+      cidr_blocks = ["0.0.0.0/0"]
+    }
+
+    tags  = {
+      Name = "Only HTTP inbound & ALL protocols outbound"
+    }
+}
+
+# AWS target group for VPC & ALB
+resource "aws_lb_target_group" "terra_alb_target_grp" {
+  name     = "terra-alb-target-grp"
+  port     = 80
+  protocol = "HTTP"
+  vpc_id   = local.terra_vpc_id
+}

ami.tf

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+# AMI part
+# EC2 instance with Apache2 webserver & website for AMI
+resource "aws_instance" "terra_ec2_for_ami" {
+    ami = "ami-08df646e18b182346" # ap-south-1
+    instance_type = "t2.micro"
+
+    subnet_id = aws_subnet.autoscaling_ws_sub_1.id
+    security_groups = [aws_security_group.terra_sg.id]
+
+    associate_public_ip_address = true
+    key_name = "AWS_AMI"          # key-pair for ssh login && installing webserver with website
+    user_data = <<EOF
+#!/bin/bash
+yum update -y
+yum install -y httpd
+systemctl start httpd
+systemctl enable httpd
+sudo yum install -y curl
+sudo curl -L -O https://github.com/codeplusmath/autoscaling-website/archive/refs/heads/master.zip
+sudo unzip master.zip
+sudo cp -r ./autoscaling-website-master/* /var/www/html/
+EOF
+
+    tags = {
+      Name = "Terra_ec2"
+    }
+}
+
+# Creating AMI from above instance
+resource "aws_ami_from_instance" "terra_ami" {
+    name = "terra_ami"
+    source_instance_id = aws_instance.terra_ec2_for_ami.id
+
+    tags = {
+      Name = "Terra_AMI"
+    }
+}
+
+
+# Launch configuration using Custom AMI
+resource "aws_launch_template" "terra_lt" {
+    image_id      = aws_ami_from_instance.terra_ami.id
+    name = "terra_lt"
+    instance_type = "t2.micro"
+    key_name = "AWS_AMI"
+
+    user_data = "${base64encode(<<EOF
+#!/bin/bash
+echo "$(hostname -f)" > /var/www/html/ip.txt
+EOF
+)}"
+
+    network_interfaces {
+    	associate_public_ip_address = true
+    	security_groups = [aws_security_group.terra_sg.id]
+    }
+
+    tags = {
+    	Name = "terra_lt"
+    }
+}

asg.tf

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+# ASG(Auto Scaling Group) Part
+resource "aws_autoscaling_group" "terra_asg" {
+    name = "terra_asg"
+    target_group_arns = [aws_lb_target_group.terra_alb_target_grp.arn]
+
+    health_check_type = "ELB"
+    health_check_grace_period = 30
+
+    vpc_zone_identifier = [aws_subnet.autoscaling_ws_sub_1.id, aws_subnet.autoscaling_ws_sub_2.id]
+
+
+    desired_capacity = 2
+    max_size = 4
+    min_size = 1
+
+    enabled_metrics = [
+        "GroupMinSize",
+        "GroupMaxSize",
+        "GroupDesiredCapacity",
+        "GroupInServiceInstances",
+        "GroupTotalInstances"
+    ]
+    metrics_granularity = "1Minute"
+
+    launch_template {
+        id = local.launch_template_id
+        version = "$Latest"
+    }
+
+    tag {
+        key = "Name"
+        value = "Terra_asg"
+        propagate_at_launch = true
+    }
+}
+
+# AutoScaling Policies
+# Scale Up Policy
+resource "aws_autoscaling_policy" "terra_scaleup" {
+    name = "terra_scaleup"
+    scaling_adjustment = 1
+    adjustment_type = "ChangeInCapacity"
+    cooldown = 30
+    autoscaling_group_name = aws_autoscaling_group.terra_asg.name
+}
+
+# Cloudwatch Alarm
+resource "aws_cloudwatch_metric_alarm" "terra_scaleup_alarm" {
+    alarm_name = "terra_scaleup_alarm"
+    comparison_operator = "GreaterThanOrEqualToThreshold"
+    evaluation_periods = "1"
+    metric_name = "RequestCountPerTarget"
+
+    namespace = "AWS/ApplicationELB"
+    period = "60"
+    statistic = "Sum"
+    threshold = "100"
+
+    dimensions = {
+        TargetGroup = aws_lb_target_group.terra_alb_target_grp.arn_suffix
+        LoadBalancer = aws_lb.terra_alb.arn_suffix
+    }
+
+    alarm_description = "Trigger when recieve more that 100 requests in 60 sec for alb"
+    alarm_actions = [aws_autoscaling_policy.terra_scaleup.arn]
+}
+
+# Scale Down Policy
+resource "aws_autoscaling_policy" "terra_scaledown" {
+    name = "terra_scaledown"
+    scaling_adjustment = -1
+    adjustment_type = "ChangeInCapacity"
+    cooldown = 30
+    autoscaling_group_name = aws_autoscaling_group.terra_asg.name
+}
+
+# CloudWatch Alarm
+resource "aws_cloudwatch_metric_alarm" "terra_scaledown_alarm" {
+    alarm_name = "terra_scaledown_alarm"
+    comparison_operator = "LessThanOrEqualToThreshold"
+    evaluation_periods = "1"
+    metric_name = "RequestCountPerTarget"
+
+    namespace = "AWS/ApplicationELB"
+    period = "60"
+    statistic = "Sum"
+    threshold = "100"
+
+    dimensions = {
+        TargetGroup = aws_lb_target_group.terra_alb_target_grp.arn_suffix
+        LoadBalancer = aws_lb.terra_alb.arn_suffix
+    }
+
+    alarm_description = "Trigger when recieve less that 100 requests in 60 sec for alb"
+    alarm_actions = [aws_autoscaling_policy.terra_scaledown.arn]
+}

main.tf

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+# AWS Virtual Private Cloud (VPC)
+resource "aws_vpc" "terra_autoscalingwebserver_vpc" {
+    cidr_block = var.VPC_CIDR_BLOCK             # associating CIDR block (11.0.0.0/24)
+
+    tags = {
+        Name = "Terra Auto Scaling Webserver"
+    }
+}
+
+# AWS subnet 1 in ap-south-1a region
+resource "aws_subnet" "autoscaling_ws_sub_1" {
+    vpc_id = aws_vpc.terra_autoscalingwebserver_vpc.id          # creating subnet in custom VPC
+    cidr_block = var.SUBNET_CIDR_BLOCK_1          # CIDR Block - 11.0.0.0/25 (0-127 ip addresses available)
+    availability_zone = "ap-south-1a"
+
+    tags = {
+        Name = "AutoScalingWebserver subnet 1"
+    }
+}
+
+# AWS subnet 2 in ap-south-1b region
+resource "aws_subnet" "autoscaling_ws_sub_2" {
+    vpc_id = aws_vpc.terra_autoscalingwebserver_vpc.id          # creating subnet in custom VPC
+    cidr_block = var.SUBNET_CIDR_BLOCK_2          # CIDR Block - 11.0.0.128/25 (128-255 ip addresses available)
+    availability_zone = "ap-south-1b"
+
+    tags = {
+        Name = "AutoScalingWebserver subnet 2"
+    }
+}
+
+# Internet Gateway
+resource "aws_internet_gateway" "autoscaling_igw" {
+    vpc_id = aws_vpc.terra_autoscalingwebserver_vpc.id
+
+    tags = {
+        Name = "Internet Gateway"
+    }
+}

out.tf

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+# VPC id
+output "terraform_vpc_id" {
+  value = local.terra_vpc_id
+}
+
+# ALB DNS
+output "terra_alb_dns" {
+  value = local.alb_dns
+}

provider.tf

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+terraform {
+    required_providers {
+        aws = {
+            source = "hashicorp/aws"
+            version = "4.22.0"
+        }
+    }
+}
+
+
+provider "aws" {
+    region = var.AWS_REGION
+    access_key = var.AWS_ACCESS_KEY
+    secret_key = var.AWS_SECRET_KEY
+}

routetable.tf

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+# Route Table Internet Gateway
+resource "aws_route_table" "terra_VPC_routetble" {
+    vpc_id = aws_vpc.terra_autoscalingwebserver_vpc.id
+
+    route{
+        cidr_block = "0.0.0.0/0"
+        gateway_id = aws_internet_gateway.autoscaling_igw.id
+    }
+
+    tags = {
+        Name = "Custom Public Subnet in terra VPC"
+    }
+}
+
+# Associating routes with VPC subnets
+resource "aws_route_table_association" "public_vpc_subnet_1a" {
+    subnet_id = aws_subnet.autoscaling_ws_sub_1.id
+    route_table_id = aws_route_table.terra_VPC_routetble.id
+}
+
+resource "aws_route_table_association" "public_vpc_subnet_1b" {
+    subnet_id = aws_subnet.autoscaling_ws_sub_2.id
+    route_table_id = aws_route_table.terra_VPC_routetble.id
+}

sg.tf

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+# AWS security groups for VPC & ASG
+resource "aws_security_group" "terra_sg" {
+    name = "terra_sg"
+    description = "Allow http connection"
+    vpc_id = aws_vpc.terra_autoscalingwebserver_vpc.id
+
+    ingress {
+        description = "HTTP connection inbound"
+        from_port = 80
+
+        to_port = 80
+        protocol = "tcp"
+        cidr_blocks = ["0.0.0.0/0"]
+    }
+
+    ingress {
+        description = "SSH connection inbound"
+        from_port = 22
+
+        to_port = 22
+        protocol = "tcp"
+        cidr_blocks = ["0.0.0.0/0"]
+    }
+
+
+    egress {
+        from_port = 0
+        to_port = 0
+        protocol = "-1"
+        cidr_blocks = ["0.0.0.0/0"]
+    }
+
+    tags = {
+        Name = "terra_sg"
+    }
+}