New to terraform so i'm hoping this is an easy issue. I'm creating some resources in azure and deploying a simple flask application to AKS. Creating works fine using terraform plan. I can see that azure is provisioned correctly and I can hit the flask app.

When I try to run terraform destroy I get the error - "StatusCode=400...In order to delete the public IP, disassociate/detach the Public IP address from the resource.

Main.tf

variable "subscription_id" {}
variable "client_id" {}
variable "client_secret" {}
variable "tenant_id" {}

provider "azurerm" {
    version         = "=1.28.0"
    tenant_id       = "${var.tenant_id}"
    subscription_id = "${var.subscription_id}"
}

resource "azurerm_resource_group" "aks" {
    name        = "${var.name_prefix}"
    location    = "${var.location}"
}

resource "azurerm_kubernetes_cluster" "k8s" {
    name                    = "${var.name_prefix}-aks"
    kubernetes_version      = "${var.kubernetes_version}"
    location                = "${azurerm_resource_group.aks.location}"
    resource_group_name     = "${azurerm_resource_group.aks.name}"
    dns_prefix              = "AKS-${var.dns_prefix}"

    agent_pool_profile {
        name                = "${var.node_pool_name}"
        count               = "${var.node_pool_size}"
        vm_size             = "${var.node_pool_vmsize}"
        os_type             = "${var.node_pool_os}"
        os_disk_size_gb     = 30
    }

    service_principal {
        client_id           = "${var.client_id}"
        client_secret       = "${var.client_secret}"
    }

    tags = {
        environment = "${var.env_tag}"
    }
}

provider "helm" {
  install_tiller = true

  kubernetes {
    host                   = "${azurerm_kubernetes_cluster.k8s.kube_config.0.host}"
    client_certificate     = "${base64decode(azurerm_kubernetes_cluster.k8s.kube_config.0.client_certificate)}"
    client_key             = "${base64decode(azurerm_kubernetes_cluster.k8s.kube_config.0.client_key)}"
    cluster_ca_certificate = "${base64decode(azurerm_kubernetes_cluster.k8s.kube_config.0.cluster_ca_certificate)}"
  }
}

# Create Static Public IP Address to be used by Nginx Ingress
resource "azurerm_public_ip" "nginx_ingress" {
  name                         = "nginx-ingress-public-ip"
  location                     = "${azurerm_kubernetes_cluster.k8s.location}"
  resource_group_name          = "${azurerm_kubernetes_cluster.k8s.node_resource_group}"
  allocation_method            = "Static"
  domain_name_label            = "${var.name_prefix}"
}

# Add Kubernetes Stable Helm charts repo
data "helm_repository" "stable" {
  name = "stable"
  url  = "https://kubernetes-charts.storage.googleapis.com"
}

# Install Nginx Ingress using Helm Chart
resource "helm_release" "nginx_ingress" {
  name       = "nginx-ingress"
  repository = "${data.helm_repository.stable.metadata.0.name}"
  chart      = "nginx-ingress"

  set {
    name  = "rbac.create"
    value = "false"
  }

  set {
    name  = "controller.service.externalTrafficPolicy"
    value = "Local"
  }

  set {
    name  = "controller.service.loadBalancerIP"
    value = "${azurerm_public_ip.nginx_ingress.ip_address}"
  }
}

Also deploying my kubernetes stuff in this file k8s.tf

provider "kubernetes" {
    host                    = "${azurerm_kubernetes_cluster.k8s.kube_config.0.host}"
    username                = "${azurerm_kubernetes_cluster.k8s.kube_config.0.username}"
    password                = "${azurerm_kubernetes_cluster.k8s.kube_config.0.password}"
    client_certificate      = "${base64decode(azurerm_kubernetes_cluster.k8s.kube_config.0.client_certificate)}"
    client_key              = "${base64decode(azurerm_kubernetes_cluster.k8s.kube_config.0.client_key)}"
    cluster_ca_certificate  = "${base64decode(azurerm_kubernetes_cluster.k8s.kube_config.0.cluster_ca_certificate)}"
}

resource "kubernetes_deployment" "flask-api-deployment" {
    metadata {
        name = "flask-api-deployment"
    }

    spec {
        replicas = 2

        selector {
            match_labels {
                component = "api"
            }
        }

        template {
            metadata {
                labels = {
                    component = "api"
                }
            }

            spec {
                container {
                    image = "xxx.azurecr.io/sampleflask:0.1.0"
                    name = "flask-api"
                    port {
                        container_port = 5000
                    }
                }
            }
        }
    }
}

resource "kubernetes_service" "api-cluster-ip-service" {
    metadata {
        name = "flask-api-cluster-ip-service"
    }

    spec {
        selector {
            component = "api"
        }

        port {
            port = 5000
            target_port = 5000
        }
    }
}

resource "kubernetes_ingress" "flask-ingress-service" {
    metadata {
        name = "flask-ingress-service"
    }

    spec {
        backend {
            service_name = "flask-api-cluster-ip-service"
            service_port = 5000
        }
    }
}