trying use VMSS MSI to mount azure file share on Ubuntu 16.04, but failed.

custom_share.tf

resource "azurerm_role_definition" "custom_share" {
  name        = "custom_share"
  scope       = "${data.azurerm_resource_group.current.id}"
  description = "This is a custom role created via Terraform"

  permissions {
    actions = [
      "*",
      "*/read",
    ]

    not_actions = [
      "Microsoft.Authorization/*/Delete",
      "Microsoft.Authorization/*/Write",
      "Microsoft.Authorization/elevateAccess/Action",
    ]

    data_actions = [
      "*",
      "*/read",
    ]
  }

  assignable_scopes = [
    "${data.azurerm_resource_group.current.id}",
  ]
}

resource "azurerm_role_assignment" "webap_vmss" {
  scope = "${azurerm_storage_account.juizstoragevmss.id}"

  #role_definition_name = "Contributor"
  role_definition_id = "${azurerm_role_definition.custom_share.id}"
  principal_id       = "${lookup(azurerm_virtual_machine_scale_set.webap_vmss.identity[0], "principal_id")}"
}

custom_vmsss.tf

YOUR AWESOME VMSS TERRAFORM

etc_fstab

//<storage_account>.file.core.windows.net/<file_share> /storage/data/<to> cifs nofail,vers=3.0,credentials=/etc/smbcredentials/token.cred,dir_mode=0777,file_mode=0777,serverino 0 0

etc_smbcredentials_token.cred

username=<msi_client_id>
password=<msi_access_token>

get_msi_access_token.sh

#!/bin/bash
curl 'http://169.254.169.254/metadata/identity/oauth2/token?api-version=2018-02-01&resource=https%3A%2F%2Fstorage.azure.com%2F' -H Metadata:true | jq '.client_id,.access_token' -r

mount.sh

#!/bin/bash
sudo mount -a

unmount.sh

#!/bin/bash
umount -a

when mount cifs with mount -a following error will happen.

Converted password too long!
error 1 (Operation not permitted) opening credential file /etc/smbcredentials/token.cred