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Amazon Web Service (AWS)

ALB

Network
Application Load Balancer (ALB) is a feature of Elastic Load Balancing that functions at the application layer and allows you to route incoming end-user traffic to applications according to listener rules that evaluate the request in order to determine which rule to apply, and to select a target from the target group for the rule action.
aws_lb
ALB
attributes:
  • name - (Optional) The name of the LB. This name must be unique within your AWS account, can have a maximum of 32 characters, must contain only alphanumeric characters or hyphens, and must not begin or end with a hyphen. If not specified, Terraform will autogenerate a name beginning with tf-lb.
  • name_prefix - (Optional) Creates a unique name beginning with the specified prefix. Conflicts with name.
  • internal - (Optional) If true, the LB will be internal.
  • load_balancer_type - (Optional) The type of load balancer to create. Possible values are application, gateway, or network. The default value is application.
  • security_groups - (Optional) A list of security group IDs to assign to the LB. Only valid for Load Balancers of type application.
  • drop_invalid_header_fields - (Optional) Indicates whether HTTP headers with header fields that are not valid are removed by the load balancer (true) or routed to targets (false). The default is false. Elastic Load Balancing requires that message header names contain only alphanumeric characters and hyphens. Only valid for Load Balancers of type application.
  • preserve_host_header - (Optional) Indicates whether the Application Load Balancer should preserve the Host header in the HTTP request and send it to the target without any change. Defaults to false.
  • access_logs - (Optional) An Access Logs block. Access Logs documented below.
  • subnets - (Optional) A list of subnet IDs to attach to the LB. Subnets cannot be updated for Load Balancers of type network. Changing this value for load balancers of type network will force a recreation of the resource.
  • subnet_mapping - (Optional) A subnet mapping block as documented below.
  • idle_timeout - (Optional) The time in seconds that the connection is allowed to be idle. Only valid for Load Balancers of type application. Default: 60.
  • enable_deletion_protection - (Optional) If true, deletion of the load balancer will be disabled via the AWS API. This will prevent Terraform from deleting the load balancer. Defaults to false.
  • enable_cross_zone_load_balancing - (Optional) If true, cross-zone load balancing of the load balancer will be enabled. This is a network load balancer feature. Defaults to false.
  • enable_http2 - (Optional) Indicates whether HTTP/2 is enabled in application load balancers. Defaults to true.
  • enable_waf_fail_open - (Optional) Indicates whether to allow a WAF-enabled load balancer to route requests to targets if it is unable to forward the request to AWS WAF. Defaults to false.
  • customer_owned_ipv4_pool - (Optional) The ID of the customer owned ipv4 pool to use for this load balancer.
  • ip_address_type - (Optional) The type of IP addresses used by the subnets for your load balancer. The possible values are ipv4 and dualstack
  • 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.

Access Logs (access_logs) support the following:

  • bucket - (Required) The S3 bucket name to store the logs in.
  • prefix - (Optional) The S3 bucket prefix. Logs are stored in the root if not configured.
  • enabled - (Optional) Boolean to enable / disable access_logs. Defaults to false, even when bucket is specified.

Subnet Mapping (subnet_mapping) blocks support the following:

  • subnet_id - (Required) ID of the subnet of which to attach to the load balancer. You can specify only one subnet per Availability Zone.
  • allocation_id - (Optional) The allocation ID of the Elastic IP address.
  • private_ipv4_address - (Optional) A private ipv4 address within the subnet to assign to the internal-facing load balancer.
  • ipv6_address - (Optional) An ipv6 address within the subnet to assign to the internet-facing load balancer.

Associating resources with a
ALB
Resources do not "belong" to a
ALB
Rather, one or more Security Groups are associated to a resource.
Create
ALB
via Terraform:
The following HCL creates an Application Load Balancer and enables the Availability Zones for the specified subnets
Syntax:

resource "aws_lb" "test" {
 name               = "test-lb-tf"
 internal           = false
 load_balancer_type = "application"
 security_groups    = [aws_security_group.lb_sg.id]
 subnets            = [for subnet in aws_subnet.public : subnet.id]

 enable_deletion_protection = true

 access_logs {
   bucket  = aws_s3_bucket.lb_logs.bucket
   prefix  = "test-lb"
   enabled = true
 }

 tags = {
   Environment = "production"
 }
}

Create
ALB
via CLI:
Parametres:

create-load-balancer
--name <value>
[--subnets <value>]
[--subnet-mappings <value>]
[--security-groups <value>]
[--scheme <value>]
[--tags <value>]
[--type <value>]
[--ip-address-type <value>]
[--customer-owned-ipv4-pool <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 elbv2 create-load-balancer \
   --name my-load-balancer \
   --subnets subnet-b7d581c0 subnet-8360a9e7

Best Practices for
ALB

Categorized by Availability, Security & Compliance and Cost

Warning
Ensure Application Load Balancer (ALB) has access logging enabled
No items found.
Critical
Ensure default security groups are not in use by ALB
Warning
Resource is Internet facing via ALB
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