docs/plans-executions/2026-09-04-1404-kvm-provider.md

@@ -81,7 +81,9 @@ The metadata element is written with a default namespace
 marshal. libvirt may hand it back prefixed; `parseInstanceMetadata` is
 tested against both spellings since `encoding/xml` matches on the namespace
 URI. Whether libvirt accepts the default-namespace form on `DomainDefineXML`
-is confirmed in Step 6 against a real host, not here.
+is confirmed in Step 6 against a real host, not here. (Step 7: it does,
+but `DomainGetMetadata` returns the element with no namespace at all; the
+parser now matches on local name only.)
 
 Checked before relying on `github.com/kdomanski/iso9660` for the seed: its
 filename mangling lowercases and keeps `-`, so `user-data`/`meta-data`/
@@ -445,3 +447,18 @@ paths the fake reports.
 
 Worth noting: the first two runs left the base image and its marker in
 the pool as designed, so later runs skip the 435 MB download.
+
+### Run 3: `parsing domain metadata: expected element <instance> in name space … but have no name space`
+
+With file-backed disks, Create returned in 1 s (image cached) and the
+domain started. Get then failed to parse the metadata: libvirt 11.6 finds
+the element by our URI but returns it as a bare `<instance>` with no
+namespace declaration at all. Step 2 had tested the default-namespace and
+prefixed spellings and left "does libvirt accept the default-namespace
+form" for the real host; it does, it just does not give it back that way.
+
+Fix: `parseInstanceMetadata` matches on the local name only, since the
+lookup already selected the element by URI. The fake now strips the
+declaration when storing metadata, so the provider's Get and ListByTag
+tests parse the shape libvirt really returns, and a new
+`TestParseInstanceMetadata_libvirtBareForm` pins it.

internal/provider/kvm/fake_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"slices"
+	"strings"
 	"sync"
 
 	libvirt "github.com/digitalocean/go-libvirt"
@@ -151,8 +152,11 @@ func (f *fakeAPI) DomainDefineXML(raw string) (libvirt.Domain, error) {
 	if err != nil {
 		return libvirt.Domain{}, lvError(libvirt.ErrXMLError, "%v", err)
 	}
+	// libvirt hands the element back without its namespace declaration
+	// (seen on 11.6); mimic that so Get/ListByTag parse the real shape.
+	stored := strings.Replace(string(meta), ` xmlns="`+metadataURI+`"`, "", 1)
 	existing := f.domains[d.Name]
-	nd := &fakeDomain{name: d.Name, xml: raw, metadata: string(meta)}
+	nd := &fakeDomain{name: d.Name, xml: raw, metadata: stored}
 	if existing != nil {
 		nd.running = existing.running
 		nd.addrs = existing.addrs

internal/provider/kvm/metadata.go

@@ -31,15 +31,21 @@ func newInstanceMetadata(uid string, createdAt time.Time) instanceMetadata {
 }
 
 // parseInstanceMetadata decodes the element as DomainGetMetadata returns it.
-// libvirt may re-serialise it with a namespace prefix rather than the default
-// namespace it was defined with; encoding/xml matches on namespace URI, so
-// both spellings decode.
+// libvirt selects the element by namespace URI but serialises it without the
+// declaration (observed on libvirt 11.6: a bare <instance>), and other
+// versions may keep a default or prefixed form. The URI is already checked
+// by the lookup, so only the local name is matched here.
 func parseInstanceMetadata(s string) (instanceMetadata, error) {
-	var m instanceMetadata
-	if err := xml.Unmarshal([]byte(s), &m); err != nil {
+	var raw struct {
+		XMLName   xml.Name `xml:"instance"`
+		Managed   string   `xml:"managed"`
+		UID       string   `xml:"uid"`
+		CreatedAt string   `xml:"createdAt"`
+	}
+	if err := xml.Unmarshal([]byte(s), &raw); err != nil {
 		return instanceMetadata{}, fmt.Errorf("parsing domain metadata: %w", err)
 	}
-	return m, nil
+	return instanceMetadata{Managed: raw.Managed, UID: raw.UID, CreatedAt: raw.CreatedAt}, nil
 }
 
 func (m instanceMetadata) managed() bool {

internal/provider/kvm/metadata_test.go

@@ -45,6 +45,21 @@ func TestParseInstanceMetadata_libvirtPrefixedForm(t *testing.T) {
 	}
 }
 
+func TestParseInstanceMetadata_libvirtBareForm(t *testing.T) {
+	t.Parallel()
+	// What libvirt 11.6 actually returns from DomainGetMetadata: the element
+	// selected by our URI, serialised without any namespace declaration.
+	in := `<instance><managed>true</managed><uid>uid-3</uid>` +
+		`<createdAt>2026-09-10T07:30:00Z</createdAt></instance>`
+	m, err := parseInstanceMetadata(in)
+	if err != nil {
+		t.Fatalf("parseInstanceMetadata() error = %v", err)
+	}
+	if !m.managed() || m.UID != "uid-3" || m.createdAt().Minute() != 30 {
+		t.Errorf("parsed = %+v", m)
+	}
+}
+
 func TestParseInstanceMetadata_notManaged(t *testing.T) {
 	t.Parallel()
 	tests := []struct {