updates to disk file argument are not reflected on libvirt host

[muroj]

System Information

Linux distribution

Ubuntu 18.04.2 LTS

Terraform version

Terraform v0.11.14
+ provider.libvirt (unversioned)
+ provider.template v2.1.2

Provider and libvirt versions

terraform-provider-libvirt 0.5.2
Compiled against library: libvirt 4.0.0
Using library: libvirt 4.0.0

---

Checklist

• [ ] Is your issue/contribution related with enabling some setting/option exposed by libvirt that the plugin does not yet support, or requires changing/extending the provider terraform schema?

  • [ ] Make sure you explain why this option is important to you, why it should be important to everyone. Describe your use-case with detail and provide examples where possible.
  • [ ] If it is a very special case, consider using the XSLT support in the provider to tweak the definition instead of opening an issue
  • [ ] Maintainers do not have expertise in every libvirt setting, so please, describe the feature and how it is used. Link to the appropriate documentation

• [x] Is it a bug or something that does not work as expected? Please make sure you fill the version information below:

Description of Issue/Question

Changing file path in disk block and running terraform apply results in successful (according to terraform) in-place update, but does not result in a change on the host. For example, the following shows output after changing path to iso file from SLE-15-Packages-s390x-GM-DVD1.iso to SLE-15-Installer-DVD-s390x-GM-DVD1.iso:

terraform apply
data.template_file.user_data: Refreshing state...
data.template_file.network_config: Refreshing state...
libvirt_cloudinit_disk.commoninit_guest1: Refreshing state... (ID: /guestimages/data1/terraform/joe_terraf...o;5d4adfc2-9d4c-9f28-f090-f002d2df7cd0)
libvirt_volume.guest1: Refreshing state... (ID: /guestimages/data1/terraform/joe_terraform_demo.qcow2)
libvirt_domain.guest1: Refreshing state... (ID: 8680a09d-72c8-4210-a31a-0733d4f7d1c6)

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  ~ libvirt_domain.guest1
      disk.1.file: "/home/jmuro/images/isos/SLE-15-Packages-s390x-GM-DVD1.iso" => "/home/jmuro/images/isos/SLE-15-Installer-DVD-s390x-GM-DVD1.iso"


Plan: 0 to add, 1 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

libvirt_domain.guest1: Modifying... (ID: 8680a09d-72c8-4210-a31a-0733d4f7d1c6)
  disk.1.file: "/home/jmuro/images/isos/SLE-15-Packages-s390x-GM-DVD1.iso" => "/home/jmuro/images/isos/SLE-15-Installer-DVD-s390x-GM-DVD1.iso"
libvirt_domain.guest1: Modifications complete after 0s (ID: 8680a09d-72c8-4210-a31a-0733d4f7d1c6)

Apply complete! Resources: 0 added, 1 changed, 0 destroyed.

Output of terraform show (correctly) shows updated disk path:

...
libvirt_domain.guest1:
  id = 8680a09d-72c8-4210-a31a-0733d4f7d1c6
  arch = s390x
  autostart = false
  disk.# = 2
  disk.0.file = 
  disk.0.scsi = false
  disk.0.url = 
  disk.0.volume_id = /guestimages/data1/terraform/joe_terraform_demo.qcow2
  disk.0.wwn = 
  disk.1.file = /home/jmuro/images/isos/SLE-15-Installer-DVD-s390x-GM-DVD1.iso
  disk.1.scsi = false

However, output of virsh dumpxml on host showing old path still in-use:

<domain type='kvm' id='53'>
  <name>joe_terraform_demo</name>
  <uuid>8680a09d-72c8-4210-a31a-0733d4f7d1c6</uuid>
  <memory unit='KiB'>1048576</memory>
  <currentMemory unit='KiB'>1048576</currentMemory>
  <vcpu placement='static'>2</vcpu>
...
<disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/home/jmuro/images/isos/SLE-15-Packages-s390x-GM-DVD1.iso'/>
      <backingStore/>
      <target dev='hda' bus='scsi'/>
      <readonly/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>

Also, ssh'ing into guest and mounting /dev/sr0 shows installer disk is still attached.

Setup

main.tf

provider "libvirt" {
    uri = "qemu+ssh://myuser@myhost/system"
}

resource "libvirt_volume" "guest1" {
  name = "joe_terraform_demo.qcow2"
  pool = "terraform"
  base_volume_name = "sles15-sp1-master"
  base_volume_pool = "terraform"
  format = "qcow2"
}

resource "libvirt_domain" "guest1" {
  name = "joe_terraform_demo"
  vcpu = "2"
  memory = "1024"

  cloudinit = "${libvirt_cloudinit_disk.commoninit_guest1.id}"

  disk = [
      {
          volume_id = "${libvirt_volume.guest1.id}"
      },
      {
          file = "/home/jmuro/images/isos/SLE-15-Installer-DVD-s390x-GM-DVD1.iso"
          #file = "/home/jmuro/images/isos/SLE-15-Packages-s390x-GM-DVD1.iso"
      }
  ]

  network_interface {
    bridge = "mybridge"
  }

  console {
      type = "pty"
      target_port = "0"
  }

  xml {
    xslt = "${file("${path.module}/xsl/xml_overrides.xsl")}"
  }

  provisioner "local-exec" {
    command = "echo ${libvirt_domain.guest1.network_interface.0.mac}  >> domain.txt"
  }
}

Steps to Reproduce Issue

1. Change disk file argument in main.tf
2. terraform apply