workaround to get cloud-init cdrom to work when using q35 libvirt/qemu machine type with dmacvicar/libvirt terraform provider

main.tf

# Please see https://github.com/dmacvicar/terraform-provider-libvirt/issues/667
# add the snippet below to your libvirt domain definition

resource "libvirt_domain" "node_name" {
  # ...rest of domain declaration
  
  xml {
    xslt = file("${path.module}/nodes-adjust.xslt")
  }
  
}

nodes-adjust.xslt

<?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output omit-xml-declaration="yes" indent="yes"/>
  
  <!-- copy the whole xml doc to start with -->
  <xsl:template match="node()|@*">
     <xsl:copy>
       <xsl:apply-templates select="node()|@*"/>
     </xsl:copy>
  </xsl:template>

  <!-- replace <target dev='hdd'...> with <target dev='sda'...>  -->
  <xsl:template match="/domain/devices/disk[@device='cdrom']/target/@dev">
    <xsl:attribute name="dev">
      <xsl:value-of select="'sda'"/>
    </xsl:attribute>
  </xsl:template>

  <!-- replace <target bus='ide'...> with <target bus='sata'...>  -->
  <xsl:template match="/domain/devices/disk[@device='cdrom']/target/@bus">
    <xsl:attribute name="bus">
      <xsl:value-of select="'sata'"/>
    </xsl:attribute>
  </xsl:template>
  
  <!-- replace <alias...> with nothing ie delete the <alias...> element  -->
  <xsl:template match="/domain/devices/disk[@device='cdrom']/alias" />
  
</xsl:stylesheet>