Initial prototype of a XML transformation hook based on XSLT

examples/xslt/main.tf

@@ -0,0 +1,16 @@
+provider "libvirt" {
+  uri = "qemu:///system"
+}
+
+resource "libvirt_domain" "xslt-demo-domain" {
+  name = "xslt-demo-domain"
+  memory = "512"
+
+  network_interface {
+    network_name = "default"
+  }
+
+  xml {
+    xslt = "${file("nicmodel.xsl")}"
+  }
+}

examples/xslt/nicmodel.xsl

@@ -0,0 +1,17 @@
+<?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"/>
+  <xsl:template match="node()|@*">
+     <xsl:copy>
+       <xsl:apply-templates select="node()|@*"/>
+     </xsl:copy>
+  </xsl:template>
+
+  <xsl:template match="/domain/devices/interface[@type='network']/model/@type">
+    <xsl:attribute name="type">
+      <xsl:value-of select="'e1000'"/>
+    </xsl:attribute>
+  </xsl:template>
+
+</xsl:stylesheet>

libvirt/resource_libvirt_domain.go

@@ -348,6 +348,20 @@ func resourceLibvirtDomain() *schema.Resource {
 				Default:  false,
 				ForceNew: false,
 			},
+			"xml": {
+				Type:     schema.TypeList,
+				Optional: true,
+				MaxItems: 1,
+				Elem: &schema.Resource{
+					Schema: map[string]*schema.Schema{
+						"xslt": {
+							Type:     schema.TypeString,
+							Optional: true,
+							ForceNew: true,
+						},
+					},
+				},
+			},
 		},
 	}
 }
@@ -456,8 +470,12 @@ func resourceLibvirtDomainCreate(d *schema.ResourceData, meta interface{}) error
 	if err != nil {
 		return fmt.Errorf("Error serializing libvirt domain: %s", err)
 	}
+	log.Printf("[DEBUG] Generated XML for libvirt domain:\n%s", data)
 
-	log.Printf("[DEBUG] Creating libvirt domain with XML:\n%s", data)
+	data, err = transformResourceXML(data, d)
+	if err != nil {
+		return fmt.Errorf("Error applying XSLT stylesheet: %s", err)
+	}
 
 	domain, err := virConn.DomainDefineXML(data)
 	if err != nil {

libvirt/resource_libvirt_domain_test.go

@@ -1271,3 +1271,118 @@ func TestAccLibvirtDomain_Import(t *testing.T) {
 		},
 	})
 }
+
+func TestAccLibvirtDomain_XSLT_UnsupportedAttribute(t *testing.T) {
+	var domain libvirt.Domain
+	randomDomainName := acctest.RandString(10)
+	randomNetworkName := acctest.RandString(10)
+
+	var config = fmt.Sprintf(`
+	resource "libvirt_network" "%s" {
+	  name      = "%s"
+  	  addresses = ["10.17.3.0/24"]
+    }
+
+	resource "libvirt_domain" "%s" {
+	  name = "%s"
+	  network_interface = {
+	    network_name = "default"
+	  }
+      xml {
+        xslt = <<EOF
+		<?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"/>
+		  <xsl:template match="node()|@*">
+			 <xsl:copy>
+			   <xsl:apply-templates select="node()|@*"/>
+			 </xsl:copy>
+		  </xsl:template>
+
+		  <xsl:template match="/domain/devices/interface[@type='network']/model/@type">
+			<xsl:attribute name="type">
+			  <xsl:value-of select="'e1000'"/>
+			</xsl:attribute>
+		  </xsl:template>
+
+		</xsl:stylesheet>
+EOF
+      }
+	}`, randomNetworkName, randomNetworkName, randomDomainName, randomDomainName)
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckLibvirtDomainDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: config,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckLibvirtDomainExists("libvirt_domain."+randomDomainName, &domain),
+					testAccCheckLibvirtDomainDescription(&domain, func(domainDef libvirtxml.Domain) error {
+						if  domainDef.Devices.Interfaces[0].Model.Type != "e1000" {
+							return fmt.Errorf("Expecting XSLT to tranform network model to e1000")
+						}
+						return nil
+					}),
+				),
+			},
+		},
+	})
+}
+
+func TestAccLibvirtDomain_XSLT_SupportedAttribute(t *testing.T) {
+	var domain libvirt.Domain
+	randomDomainName := acctest.RandString(10)
+	randomNetworkName := acctest.RandString(10)
+
+	var config = fmt.Sprintf(`
+	resource "libvirt_network" "%s" {
+	  name      = "%s"
+  	  addresses = ["10.17.3.0/24"]
+    }
+
+	resource "libvirt_domain" "%s" {
+	  name = "%s"
+	  network_interface = {
+	    network_name = "default"
+	  }
+      xml {
+        xslt = <<EOF
+        <?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"/>
+              <xsl:template match="node()|@*">
+              <xsl:copy>
+                <xsl:apply-templates select="node()|@*"/>
+              </xsl:copy>
+            </xsl:template>
+
+            <xsl:template match="/domain/devices/interface[@type='network']/source/@network">
+              <xsl:attribute name="network">
+                <xsl:value-of select="'%s'"/>
+              </xsl:attribute>
+            </xsl:template>
+          </xsl:stylesheet>
+EOF
+      }
+	}`, randomNetworkName, randomNetworkName, randomDomainName, randomDomainName, randomNetworkName)
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckLibvirtDomainDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: config,
+				ExpectNonEmptyPlan: true,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckLibvirtDomainExists("libvirt_domain."+randomDomainName, &domain),
+					resource.TestCheckResourceAttr(
+						"libvirt_domain."+randomDomainName, "network_interface.0.network_name", randomNetworkName),
+				),
+			},
+		},
+	})
+}

libvirt/utils_xslt.go

@@ -0,0 +1,59 @@
+package libvirt
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/hashicorp/terraform/helper/schema"
+)
+
+// this function applies a XSLT transform to the xml data
+// and is to be reused in all resource types
+// your resource need to have a xml.xslt element in the schema
+func transformResourceXML(xml string, d *schema.ResourceData) (string, error) {
+	xslt, ok := d.GetOk("xml.0.xslt")
+	if !ok {
+		return xml, nil
+	}
+
+	xsltFile, err := ioutil.TempFile("", "terraform-provider-libvirt-xslt")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.Remove(xsltFile.Name()) // clean up
+
+	// we trim the xslt as it may contain space before the xml declaration
+	// because of HCL heredoc
+	if _, err := xsltFile.Write([]byte(strings.TrimSpace(xslt.(string)))); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := xsltFile.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	xmlFile, err := ioutil.TempFile("", "terraform-provider-libvirt-xml")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.Remove(xmlFile.Name()) // clean up
+
+	if _, err := xmlFile.Write([]byte(xml)); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := xmlFile.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	cmd := exec.Command("xsltproc", xsltFile.Name(), xmlFile.Name())
+	transformedXML, err := cmd.Output()
+	if err != nil {
+		return xml, err
+	}
+	log.Printf("[DEBUG] Transformed XML with user specified XSLT:\n%s", transformedXML)
+	return string(transformedXML), nil
+}