
Introduction
In today’s ever evolving tech field, every application must remain high availability for ensuring minimal downtime and robust performance. The software applications will be operational even during infrastructure failures by distributing the workload across multiple availability zones (AZs). Terraform is one of the popular infrastructure-as-Code (IaC) tools that simplify the process of provisioning highly available cloud architectures. It enables rapid deployment, scaling, and management of resources across multiple environments.
Key Components of a Highly Available Architecture
The highly available architecture consists of various important components, such as:
- Multiple availability zones,
- Load balancing,
- Auto-scaling,
- Database replication,
- Monitoring and alerts.
Step-by-Step Deployment of a Highly Available Architecture
The deployment process of a highly available architecture consists of:
- Setting Up the Cloud Provider,
- Creating a VPC with Subnets Across Multiple AZs,
- Configuring a Load Balancer,
- Deploying EC2 Instances with Auto-Scaling
Setting Up the Cloud Provider
Terraform allows the configuration of various cloud providers, like AWS. The region should be chosen based on the geographic requirements and the availability of services.
Creating a VPC with Subnets Across Multiple AZs
The fundamental building block for deploying resources in AWS is Virtual Private Cloud (VPC). Create public and private subnets in multiple AZs for the highly available architecture. To create a VPC with two public and two private subnets, follow the below codes to span different availability zones.
Configuring a Load Balancer
To ensure failover and load balancing across the available instances, the traffic has to be distributed across multiple instances and AZs. So, we create an application load balancer and a target group to forward requests to the instances.
resource "aws_lb" "alb" { name = "high-availability-alb" internal = false load_balancer_type = "application" security_groups = [aws_security_group.alb_sg.id] subnets = aws_subnet.public[*].id } resource "aws_lb_target_group" "tg" { name = "app-tg" port = 80 protocol = "HTTP" vpc_id = aws_vpc.main.id } resource "aws_lb_listener" "listener" { load_balancer_arn = aws_lb.alb.arn port = 80 protocol = "HTTP" default_action { type = "forward" target_group_arn = aws_lb_target_group.tg.arn } }
Deploying EC2 Instances with Auto-Scaling
The important part of high availability is ensuring the scalability of the architecture based on the demand. Terraform can manage auto-scaling groups for EC2 instances. The configuration can deploy an auto-scaling group that adjusts the number of EC2 instances based on traffic is shown below:
resource "aws_launch_configuration" "app" { name = "app-launch-configuration" image_id = "ami-0c55b159cbfafe1f0" instance_type = "t2.micro" security_groups = [aws_security_group.instance_sg.id] } resource "aws_autoscaling_group" "asg" { vpc_zone_identifier = aws_subnet.private[*].id launch_configuration = aws_launch_configuration.app.id min_size = 2 max_size = 4 desired_capacity = 2 health_check_type = "EC2" health_check_grace_period = 300 }
Configuring a Multi-AZ Database
Multi-AZ support is essential to ensure that the database automatically switches to another if one AZ goes down. Set up a MySQL database with multi-AZ failover.
resource "aws_db_instance" "main" { identifier = "high-availability-db" engine = "mysql" instance_class = "db.t3.micro" allocated_storage = 20 name = "mydb" username = "admin" password = "mypassword" multi_az = true publicly_accessible = false vpc_security_group_ids = [aws_security_group.db_sg.id] db_subnet_group_name = aws_db_subnet_group.main.name }
Setting Up Security Groups
For any highly available system, security is important as infrastructure. Security groups control access to the EC2 instances, databases, and load balancers.
resource "aws_security_group" "alb_sg" { vpc_id = aws_vpc.main.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"] } } resource "aws_security_group" "instance_sg" { vpc_id = aws_vpc.main.id ingress { from_port = 22 to_port = 22 protocol = "tcp" cidr_blocks = ["0.0.0.0/0"] } 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"] } }
Monitoring and Alerts
To complete a highly available architecture, set up monitoring and alerting systems. AWS CloudWatch integrates into the Terraform setup to monitor metrics like:
CPU utilization, Memory usage, Overall health of the infrastructure.Alerts can be triggered when predefined thresholds are breached that maintains availability by acting quickly on issues.
resource "aws_cloudwatch_metric_alarm" "high_cpu" { alarm_name = "high_cpu_alarm" comparison_operator = "GreaterThanOrEqualToThreshold" evaluation_periods = "2" metric_name = "CPUUtilization" namespace = "AWS/EC2" period = "300" statistic = "Average" threshold = "80" alarm_actions = [aws_sns_topic.alert.arn] }
Conclusion
To wrap up, deployment of any highly available architecture with Terraform involves including multiple availability zones, load balancing, auto-scaling, and redundant databases. To acquire the skills of terraform, Credo Systemz provides the Terraform course in Chennai. Learn to leverage terraform with AWS effectively by combining the right components, such as VPCs, subnets, load balancers, EC2 instances, and databases.
Join Credo Systemz Software Courses in Chennai at Credo Systemz OMR, Credo Systemz Velachery to kick-start or uplift your career path.