fix(cloud): fedora docker install and debian 9p cloud-init error

internal/cloudinit/cloudinit.go

@@ -103,7 +103,10 @@ func extraPackages(osName string) string {
 func userData(v *config.VM, pubkey string, recipeBodies []string) (string, error) {
 	base := fmt.Sprintf(userDataTemplate, guestShell(v.OS), pubkey, consolePasswordBlock(v.ConsolePassword))
 
-	docs := []string{base, mountsDoc(v)}
+	docs := []string{base}
+	if m := mountsDoc(v); m != "" {
+		docs = append(docs, m)
+	}
 	if extra := extraPackages(v.OS); extra != "" {
 		docs = append(docs, extra)
 	}
@@ -116,11 +119,20 @@ func userData(v *config.VM, pubkey string, recipeBodies []string) (string, error
 // QEMU command line with nothing to mount them, so the share silently did
 // nothing.
 //
-// nofail is required: some cloud kernels ship no 9p module (Debian's does
-// not), and without nofail an unmountable share holds up boot. The host
-// mount is ro, matching what QEMU enforces, so a write fails immediately
+// debian's cloud kernel (deb13-cloud) ships no 9p module, so the mount can
+// never succeed and cloud-init's mounts module marks the whole seed as
+// errored on every boot. Skip the mounts for debian; the 9p share does not
+// work there.
+// ponytail: keyed on the one bundled image without 9p. Add another OS here if
+// the catalog gains a second 9p-less image.
+//
+// nofail keeps a share that drops out at runtime from holding up boot. The
+// host mount is ro, matching what QEMU enforces, so a write fails immediately
 // instead of after a remount that appears to succeed.
 func mountsDoc(v *config.VM) string {
+	if v.OS == "debian" {
+		return ""
+	}
 	const opts = "trans=virtio,version=9p2000.L,%s,_netdev,nofail"
 	var b strings.Builder
 	b.WriteString("#cloud-config\nmounts:\n")

internal/cloudinit/cloudinit_test.go

@@ -17,10 +17,11 @@ import (
 // tests can inspect individual documents instead of grepping the whole
 // rendered file.
 
-// withoutMounts returns the archive's documents minus the 9p mounts document,
-// and fails if there isn't exactly one. Every VM gets a mounts document, so
-// tests about the base and recipe documents filter it out instead of counting
-// around it.
+// withoutMounts returns the archive's documents minus the 9p mounts document.
+// Every VM except debian gets one mounts document; debian's cloud kernel has
+// no 9p module, so it gets none. The helper accepts zero or one and fails on
+// more, so tests about the base and recipe documents filter it out instead of
+// counting around it.
 func withoutMounts(t *testing.T, ud string) []archiveDoc {
 	t.Helper()
 	var rest []archiveDoc
@@ -32,8 +33,8 @@ func withoutMounts(t *testing.T, ud string) []archiveDoc {
 		}
 		rest = append(rest, d)
 	}
-	if found != 1 {
-		t.Fatalf("want exactly one mounts document, got %d:\n%s", found, ud)
+	if found > 1 {
+		t.Fatalf("want at most one mounts document, got %d:\n%s", found, ud)
 	}
 	return rest
 }
@@ -445,6 +446,27 @@ func TestSeedInstallsSudoWhereItIsMissing(t *testing.T) {
 	}
 }
 
+// debian's cloud kernel has no 9p module, so the seed omits the mounts
+// document. A present-but-unmountable 9p entry made cloud-init report the
+// whole seed as errored on every boot. A 9p-capable OS still gets the mounts.
+func TestSeedSkipsMountsOnDebian(t *testing.T) {
+	deb, err := userData(&config.VM{Name: "vm", OS: "debian"}, testPubkey, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(deb, "mounts:") {
+		t.Errorf("debian seed carries a 9p mounts document:\n%s", deb)
+	}
+
+	arch, err := userData(&config.VM{Name: "vm", OS: "arch"}, testPubkey, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(arch, "mounts:") {
+		t.Errorf("arch seed is missing its 9p mounts document:\n%s", arch)
+	}
+}
+
 // Recipe fragments must still merge after the base block, whatever the OS:
 // this is the existing contract and the reason the cloud-config-archive
 // exists (see buildArchive).

internal/recipes/bundled/docker/install-fedora.sh

@@ -3,9 +3,10 @@
 # Fedora VM.
 set -e
 
-# Add Docker's official repository
-dnf -y install dnf-plugins-core
-dnf config-manager --add-repo https://download.docker.com/linux/fedora/docker-ce.repo
+# dnf5 (Fedora 41+) dropped `config-manager --add-repo`. Write the repo file
+# directly; that works on both dnf4 and dnf5.
+curl -fsSL https://download.docker.com/linux/fedora/docker-ce.repo \
+    -o /etc/yum.repos.d/docker-ce.repo
 
 dnf install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin