Deploying AWS load balancers with Terraform turns an otherwise manual, error-prone networking task into a repeatable infrastructure definition. Terraform is an open source Infrastructure as Code tool created by HashiCorp that allows users to define and provision data center infrastructure using a declarative configuration language called HashiCorp Configuration Language. Terraform configuration refers to a set of records containing infrastructure code written in HCL determining the ideal condition of the infrastructure.
In contemporary cloud infrastructure setups, managing and distributing incoming traffic effectively across various instances is central to ensuring the high availability and scalability of applications. Among the services given by AWS, Elastic Load Balancing stands apart as a basic component of working with this task. Elastic Load Balancer is a flexible Burden Balancer is an overseen administration given by Amazon Web Administrations that naturally disseminates approaching application traffic across different targets, for example, EC2 occasions, holders, IP locations, or Lambda capabilities, in various accessibility zones. It guarantees high accessibility, adaptation to internal failure, and adaptability of utilizations by uniformly appropriating the responsibility and rerouting traffic away from undesirable targets.
By arranging load balancer configurations, listeners, target groups, and related resources, groups can automate the provisioning system, ensuring consistency and reliability quality across deployments. Terraforms declarative syntax structure works on infrastructure management, empowering users to define the ideal condition of their AWS environment and apply changes reliably. The integration with AWS services, for example, Elastic Load Balancing works with high availability, fault tolerance, and scalability of applications. With Terraform, associations can undoubtedly increase assets or down, adjust to evolving responsibilities, and integrate load adjusting into their CI/CD pipelines for continuous delivery.
Terraform Module Landscape for AWS Load Balancers
Two community modules dominate practical ALB and NLB adoption.
A Terraform module which creates Application and Network Load Balancer resources on AWS provides a focused building block for ALB and NLB provisioning. When using ALB Listener rules, make sure that every rule's actions block ends in a forward, redirect, or fixed-response action so that every rule will resolve to some sort of an HTTP response.
A Terraform module containing common configurations for an AWS new style Load Balancer is available through the terraform registry. NOTE: There has been significant changes to the upstream module and this README has not been updated yet.
| Branch | Build status |
|---|---|
| master | |
| master (upstream) |
The module is intended for scenarios where you want to create a set of resources for the ALB: namely an associated target group and listener. You have created a Virtual Private Cloud and subnets where you intend to put this ALB. You have one or more security groups to attach to the ALB. You want to configure a listener for HTTPS/HTTP. You have uploaded an SSL certificate to AWS IAM if using HTTPS.
The module supports both mutually exclusive configurations:
- Internal IP ALBs
- External IP ALBs
The use-case presented here appears almost identical to how one would use an ELB but we inherit a few bonuses by moving to ALB. Those are best outlined in AWS's documentation. For an example of using ALB with ECS look no further than the hashicorp example.
A full example leveraging other community modules is contained in the examples/test_fixtures directory.
Registry Module Usage Pattern
Using a registry module reduces boilerplate and enforces consistent defaults.
A typical invocation from the registry looks like this:
hcl
module "alb" {
source = "terraform-aws-modules/alb/aws"
alb_name = "my-alb"
region = "us-east-2"
alb_security_groups = ["sg-edcd9784", "sg-edcd9785"]
vpc_id = "vpc-abcde012"
subnets = ["subnet-abcde012", "subnet-bcde012a"]
alb_protocols = ["HTTPS"]
certificate_arn = "arn:aws:iam::123456789012:server-certificate/test_cert-123456789012"
create_log_bucket = true
enable_logging = true
log_bucket_name = "logs-us-east-2-123456789012"
log_location_prefix = "my-alb-logs"
health_check_path = "/"
tags = {
"Terraform" = "true"
"Env" = "${terraform.workspace}"
}
}
Always terraform plan to see your change before running terraform apply.
This module has been packaged with awspec tests through test kitchen. To run them:
- Install rvm and the ruby version specified in the Gemfile.
- Install bundler and the gems from our Gemfile:
gem install bundler; bundle install - Ensure your AWS environment is configured for test and set TFVARregion to a valid AWS region for example export TFVARregion=${AWS_REGION}
Native Resource Composition for ALB
Manual composition gives full control over target groups, attachments, and listeners.
The variable file in Terraform serves as a centralized location for defining and managing input variables used across multiple Terraform configurations.
A minimal external ALB definition can be expressed as:
hcl
name = "External-LB"
internal = false
load_balancer_type = "application"
security_groups = [aws_security_group.web-sg.id]
subnets = [aws_subnet.public-subnet1.id, aws_subnet.public-subnet2.id]
Target group definition:
hcl
resource "aws_lb_target_group" "target_elb" {
name = "ALB-TG"
port = 80
protocol = "HTTP"
vpc_id = aws_vpc.siva.id
health_check {
path = "/health"
port = 80
protocol = "HTTP"
}
}
Target group attachments for specific instances:
```hcl
resource "awslbtargetgroupattachment" "ecomm" {
targetgrouparn = awslbtargetgroup.targetelb.arn
targetid = awsinstance.ecomm.id
port = 80
dependson = [
awslbtargetgroup.targetelb,
awsinstance.ecomm,
]
}
resource "awslbtargetgroupattachment" "food" {
targetgrouparn = awslbtargetgroup.targetelb.arn
targetid = awsinstance.food.id
port = 80
dependson = [
awslbtargetgroup.targetelb,
awsinstance.food,
]
}
```
Listener definition:
hcl
resource "aws_lb_listener" "listener_elb" {
load_balancer_arn = aws_lb.external-alb.arn
port = 80
protocol = "HTTP"
default_action {
type = "forward"
target_group_arn = aws_lb_target_group.target_elb.arn
}
}
Our point is to outfit you with the important information and abilities to engineer powerful and versatile load-balancing solutions in AWS infrastructure. We'll dig into principal ideas, and terminologies, and give a step-by-step manual for deploying AWS load balancers using Terraform.
Primary Terminologies
- AWS Elastic Load Balancer is an overseen administration given by Amazon Web Administrations that naturally disseminates approaching application traffic across different targets, for example, EC2 occasions, holders, IP locations, or Lambda capabilities, in various accessibility zones. It guarantees high accessibility, adaptation to internal failure, and adaptability of utilizations by uniformly appropriating the responsibility and rerouting traffic away from undesirable targets.
- Terraform is an open-source Infrastructure as Code tool created by HashiCorp. It allows users to define and provision data center infrastructure utilizing a declarative configuration language called HashiCorp Configuration Language. Terraform empowers clients to manage and automate the deployment of infrastructure resources across different cloud providers, including AWS, Azure, Google Cloud Platform, and others.
- Terraform Configuration refers to a set of records containing infrastructure code written in HCL, determining the ideal condition of the infrastructure
Listener Rules and Action Requirements
ALB listener rules must terminate in a resolvable HTTP response.
When you're using ALB Listener rules, make sure that every rule's actions block ends in a forward, redirect, or fixed-response action so that every rule will resolve to some sort of an HTTP response.
This constraint prevents dangling rules that would leave requests unmatched. Forward actions route to a target group, redirect actions return a 302 style response, and fixed-response actions return a configured status code and body. Mixing conditions with multiple actions requires that the final action in the list is one of these three types.
Common listener configuration properties include:
| Property | Description |
|---|---|
| loadbalancerarn | ARN of the ALB to attach the listener |
| port | Port on which the listener receives traffic |
| protocol | HTTP or HTTPS |
| default_action | Action taken when no rule matches |
Target group health check properties include:
| Property | Description |
|---|---|
| path | Health check request path |
| port | Port used for health checks |
| protocol | HTTP or HTTPS |
Module Comparison and Selection Criteria
Choosing between native resources and a module depends on operational needs.
- Use a community module when you want a set of resources for the ALB namely an associated target group and listener with standardized logging, tagging, and security group handling.
- Use native resources when you need fine-grained control over target group attachments, multiple listeners, and conditional rule ordering.
- Internal IP ALBs are used for service-to-service traffic inside a VPC.
- External IP ALBs are used for internet facing workloads.
The module supports both mutually exclusive configurations for internal and external ALBs. The use-case appears almost identical to how one would use an ELB but we inherit a few bonuses by moving to ALB.
In practice teams often start with a module for speed and then fork or extend it with native awslbtargetgroup and awslb_listener resources for specialized routing requirements.
Operational Best Practices
Effective ALB Terraform workflows combine planning, validation, and modular reuse.
- Always terraform plan to see your change before running terraform apply.
- Centralize variables in a variable file to serve as a centralized location for defining and managing input variables used across multiple Terraform configurations.
- Define security groups explicitly and attach them to the ALB before listener creation.
- For HTTPS listeners, upload an SSL certificate to AWS IAM if using HTTPS and reference the certificate ARN in the module or listener resource.
- Enable access logging to an S3 bucket with a clear log prefix per environment.
- Set healthcheckpath to a lightweight endpoint such as / that returns 200 for healthy targets.
By arranging load balancer configurations, listeners, target groups, and related resources, groups can automate the provisioning system, ensuring consistency and reliability quality across deployments. Terraform's declarative syntax structure works on infrastructure management, empowering users to define the ideal condition of their AWS environment and apply changes reliably.
Conclusion
Deploying AWS load balancers with Terraform upgrades functional effectiveness, speeds up infrastructure deployment, and enables groups to fabricate versatile and scalable architectures in the cloud. The integration of Elastic Load Balancing with Terraform allows for high availability, fault tolerance, and scalability of applications.
Modules such as the Application and Network Load Balancer module and the new style ALB/NLB module provide common configurations that accelerate adoption while native resources give precise control over target groups, attachments, and listeners. Adherence to listener rule action requirements, proper security group and subnet placement, and consistent variable management ensures reliable deployments.
With Terraform, associations can undoubtedly increase assets or down, adjust to evolving responsibilities, and integrate load adjusting into their CI/CD pipelines for continuous delivery. Generally speaking, deploying AWS load balancers with Terraform upgrades functional effectiveness, speeds up infrastructure deployment, and enables groups to fabricate versatile and scalable architectures in the cloud.