Your setup for Istio gateway

gistfile1.tf

resource "kubernetes_manifest" "k8s-istio-gateway" {
  depends_on = [
    kubernetes_manifest.k8s-wildcard-cert
  ]
  provider = kubernetes
  manifest = {
    "apiVersion" = "networking.istio.io/v1alpha3"
    "kind"       = "Gateway"
  "metadata" = {
      name = "istio-gateway"
      namespace = "istio-system"
    }
    "spec" = {
      "selector" = {
       "istio" = "ingressgateway"
      }
      "servers" = [{
        "port" = {
          "number" = 443
          "name" = "https"
          "protocol" = "HTTPS"
        },
        "tls" = {
          "mode" = "SIMPLE"
          "credentialName" = "k8s-wildcard-cert"
        },
        "hosts" = [
          "*.k8s.test.com"
        ]
      }]
    }
  }
}