If you are using Traefik in kubernetes but you want to use an AWS ALB (application load balancer) this recipe may work for you. You will note a few important things:

1. Traefik relies on the underlying kubernetes provider to create an Ingress. If not specified this will be a loadbalancer CLB (classic load balancer). There is a way to make this a NLB (network load balancer) but the AWS provider is not doing an ALB so Traefik can't do an ALB. This recipe therefore relies on a NodePort service and ties the Ingress (ALB) to the NodePort service via the ingressclass annotation. If you do not like or want to use NodePort this is not for you.
2. Yet to confirm can this recipe work if you did not intentionally install the AWS LBC (load balancer controller). And does this work on non AWS EKS or self-managed kubernetes on AWS.
3. Still looking at why the AWS Target group health check is not able to use the /ping or /dashboard. This may be an issue with my security groups but for now I just created manually a IngressRoute /<>-health on the Traefik web entrypoint and updated the Target Group health check either programatically or in the AWS console.
4. I did not want to complicate this with kubernetes so I am using the simplest way for helm to communicate with the cluster and point to the environment kube config to get to the cluster.
5. I did some minimal templating to change the helm release name and corresponding kubernetes objects but for this post I just hard coded for simplicity.
6. I commented out deployment as Daemonset for my testing. You need to decide what is better in your environment Deployment or Daemonset.

providers.tf

provider "helm" {
  kubernetes {
    config_path = "~/.kube/config-eks"
  }
}

versions.tf

terraform {
  required_providers {
    helm = {
      source  = "hashicorp/helm"
      version = ">= 2.0.1"
    }
  }
  required_version = ">= 0.15"
}

helm values

additionalArguments:
- --providers.kubernetescrd.ingressclass=traefik-pub

#deployment:
#  kind: DaemonSet

service:
  enabled: true
  type: NodePort

service:
  enabled: true
  type: NodePort
extraObjects:
  - apiVersion: networking.k8s.io/v1
    kind: Ingress
    metadata:
      name: traefik-pub
      annotations:
        kubernetes.io/ingress.class: alb
        alb.ingress.kubernetes.io/scheme: internet-facing
        alb.ingress.kubernetes.io/security-groups: sg-<eks-sg1>,<eks-sg2>
        #alb.ingress.kubernetes.io/actions.ssl-redirect: '{"Type": "redirect", "RedirectConfig":
        #  { "Protocol": "HTTPS", "Port": "443", "StatusCode": "HTTP_301"}}'
        alb.ingress.kubernetes.io/backend-protocol: HTTP
        alb.ingress.kubernetes.io/certificate-arn: arn:aws:acm:us-east-1:<aws account id>:certificate/b6ead273-66e9-4768-ad25-0924dca35cdb
        alb.ingress.kubernetes.io/healthcheck-path: "/traefik-pub-health"
        alb.ingress.kubernetes.io/healthcheck-port: "traffic-port"
        #alb.ingress.kubernetes.io/healthcheck-protocol: HTTP
        alb.ingress.kubernetes.io/listen-ports: '[{"HTTP": 80}, {"HTTPS":443}]'
    spec:
      defaultBackend:
        service:
          name: traefik-pub
          port:
            number: 80  

ingressClass:
  enabled: true
  isDefaultClass: false

ingressRoute:
  dashboard:
    enabled: true
    # Additional ingressRoute annotations (e.g. for kubernetes.io/ingress.class)
    annotations:
      kubernetes.io/ingress.class: traefik-pub
    # Additional ingressRoute labels (e.g. for filtering IngressRoute by custom labels)
    labels: {}
    entryPoints:
    - traefik
    labels: {}
    matchRule: PathPrefix(`/dashboard`) || PathPrefix(`/api`)
    middlewares: []
    tls: {}

rollingUpdate:
  maxUnavailable: 1
  maxSurge: 1

variables.tf (shortened for documentation)

variable "traefik_name" {
  description = "helm release name"
  type        = string
  default     = "traefik-pub"
}

variable "namespace" {
  description = "Namespace to install traefik chart into"
  type        = string
  default     = "test"
}

variable "traefik_chart_version" {
  description = "Version of Traefik chart to install"
  type        = string
  default     = "21.2.1"
}

chart.tf

resource "helm_release" "traefik" {
  namespace        = var.namespace
  create_namespace = true
  name             = var.traefik_name
  repository       = "https://traefik.github.io/charts"
  chart            = "traefik"
  version          = var.traefik_chart_version
  timeout = var.timeout_seconds

  values = [
    file("values.yml")
  ]

  set {
    name  = "deployment.replicas"
    value = var.replica_count
  }

}