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Amazon Web Service (AWS)

ELB

Network
Amazon Elastic Load Balancing (ELB) is a load balancing service for deployments that automatically distributes incoming application traffic across multiple targets and scales resources to meet traffic demands, in one or more Availability Zones (AZs).
aws_elb
ELB
attributes:
  • name - (Optional) The name of the ELB. By default generated by Terraform.
  • name_prefix - (Optional, Forces new resource) Creates a unique name beginning with the specified prefix. Conflicts with name.
  • access_logs - (Optional) An Access Logs block. Access Logs documented below.
  • availability_zones - (Required for an EC2-classic ELB) The AZ's to serve traffic in.
  • security_groups - (Optional) A list of security group IDs to assign to the ELB. Only valid if creating an ELB within a VPC
  • subnets - (Required for a VPC ELB) A list of subnet IDs to attach to the ELB.
  • instances - (Optional) A list of instance ids to place in the ELB pool.
  • internal - (Optional) If true, ELB will be an internal ELB.
  • listener - (Required) A list of listener blocks. Listeners documented below.
  • health_check - (Optional) A health_check block. Health Check documented below.
  • cross_zone_load_balancing - (Optional) Enable cross-zone load balancing. Default: true
  • idle_timeout - (Optional) The time in seconds that the connection is allowed to be idle. Default: 60
  • connection_draining - (Optional) Boolean to enable connection draining. Default: false
  • connection_draining_timeout - (Optional) The time in seconds to allow for connections to drain. Default: 300
  • desync_mitigation_mode - (Optional) Determines how the load balancer handles requests that might pose a security risk to an application due to HTTP desync. Valid values are monitor, defensive (default), strictest.
  • tags - (Optional) A map of tags to assign to the resource. If configured with a provider default_tags configuration block present, tags with matching keys will overwrite those defined at the provider-level.

Exactly one of availability_zones or subnets must be specified: this determines if the ELB exists in a VPC or in EC2-classic.

Access Logs (access_logs) support the following:

  • bucket - (Required) The S3 bucket name to store the logs in.
  • bucket_prefix - (Optional) The S3 bucket prefix. Logs are stored in the root if not configured.
  • interval - (Optional) The publishing interval in minutes. Valid values: 5 and 60. Default: 60
  • enabled - (Optional) Boolean to enable / disable access_logs. Default is true

Listeners (listener) support the following:

  • instance_port - (Required) The port on the instance to route to
  • instance_protocol - (Required) The protocol to use to the instance. Valid values are HTTP, HTTPS, TCP, or SSL
  • lb_port - (Required) The port to listen on for the load balancer
  • lb_protocol - (Required) The protocol to listen on. Valid values are HTTP, HTTPS, TCP, or SSL
  • ssl_certificate_id - (Optional) The ARN of an SSL certificate you have uploaded to AWS IAM. Note ECDSA-specific restrictions below. Only valid when lb_protocol is either HTTPS or SSL

Health Check (health_check) supports the following:

  • healthy_threshold - (Required) The number of checks before the instance is declared healthy.
  • unhealthy_threshold - (Required) The number of checks before the instance is declared unhealthy.
  • target - (Required) The target of the check. Valid pattern is "${PROTOCOL}:${PORT}${PATH}", where PROTOCOL values are:
  • HTTP, HTTPS - PORT and PATH are required
  • TCP, SSL - PORT is required, PATH is not supported
  • interval - (Required) The interval between checks.
  • timeout - (Required) The length of time before the check times out.

Associating resources with a
ELB
Resources do not "belong" to a
ELB
Rather, one or more Security Groups are associated to a resource.
Create
ELB
via Terraform:
The following HCL creates a new load balancer
Syntax:

resource "aws_elb" "bar" {
 name               = "foobar-terraform-elb"
 availability_zones = ["us-west-2a", "us-west-2b", "us-west-2c"]

 access_logs {
   bucket        = "foo"
   bucket_prefix = "bar"
   interval      = 60
 }

 listener {
   instance_port     = 8000
   instance_protocol = "http"
   lb_port           = 80
   lb_protocol       = "http"
 }

 listener {
   instance_port      = 8000
   instance_protocol  = "http"
   lb_port            = 443
   lb_protocol        = "https"
   ssl_certificate_id = "arn:aws:iam::123456789012:server-certificate/certName"
 }

 health_check {
   healthy_threshold   = 2
   unhealthy_threshold = 2
   timeout             = 3
   target              = "HTTP:8000/"
   interval            = 30
 }

 instances                   = [aws_instance.foo.id]
 cross_zone_load_balancing   = true
 idle_timeout                = 400
 connection_draining         = true
 connection_draining_timeout = 400

 tags = {
   Name = "foobar-terraform-elb"
 }
}

Create
ELB
via CLI:
Parametres:

create-load-balancer
--load-balancer-name <value>
--listeners <value>
[--availability-zones <value>]
[--subnets <value>]
[--security-groups <value>]
[--scheme <value>]
[--tags <value>]
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]
[--debug]
[--endpoint-url <value>]
[--no-verify-ssl]
[--no-paginate]
[--output <value>]
[--query <value>]
[--profile <value>]
[--region <value>]
[--version <value>]
[--color <value>]
[--no-sign-request]
[--ca-bundle <value>]
[--cli-read-timeout <value>]
[--cli-connect-timeout <value>]
[--cli-binary-format <value>]
[--no-cli-pager]
[--cli-auto-prompt]
[--no-cli-auto-prompt]

Example:

aws elb create-load-balancer --load-balancer-name my-load-balancer --listeners "Protocol=HTTP,LoadBalancerPort=80,InstanceProtocol=HTTP,InstancePort=80" --subnets subnet-15aaab61 --security-groups sg-a61988c3

Best Practices for
ELB

Categorized by Availability, Security & Compliance and Cost

Warning
ELB not in use
Critical
Ensure default security groups are not in use by ELB
Warning
Resource is Internet facing via ELB
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