ditro/rhel86: set volid like in rhel9.0

This is only required in RHEL9.0, but best practice is to always pin these things
down. Also increases uniformity between distros.

Simplify a bit the volid generator by making it require `rand.Rand` rather than
`io.Reader`, and hence eliminating the need for error handling.

internal/disk/disk.go

@@ -151,10 +151,13 @@ func newRandomUUIDFromReader(r io.Reader) (uuid.UUID, error) {
 	return id, nil
 }
 
-// NewRandomVolIDFromReader creates a random 32 bit hex string to use as a
+// NewVolIDFromRand creates a random 32 bit hex string to use as a
 // volume ID for FAT filesystems
-func NewRandomVolIDFromReader(r io.Reader) (string, error) {
+func NewVolIDFromRand(r *rand.Rand) string {
 	volid := make([]byte, 4)
-	_, err := r.Read(volid)
+	len, _ := r.Read(volid)
-	return hex.EncodeToString(volid), err
+	if len != 4 {
+		panic("expected four random bytes")
+	}
+	return hex.EncodeToString(volid)
 }

internal/distro/rhel86/pipelines.go

@@ -693,7 +693,7 @@ func edgeSimplifiedInstallerPipelines(t *imageType, customizations *blueprint.Cu
 	installerTreePipeline := simplifiedInstallerTreePipeline(repos, installerPackages, kernelVer, archName, d.product, d.osVersion, "edge", customizations.GetFDO())
 	isolabel := fmt.Sprintf(d.isolabelTmpl, archName)
 	efibootTreePipeline := simplifiedInstallerEFIBootTreePipeline(installDevice, kernelVer, archName, d.vendor, d.product, d.osVersion, isolabel, customizations.GetFDO())
-	bootISOTreePipeline := simplifiedInstallerBootISOTreePipeline(imgPipelineName, kernelVer)
+	bootISOTreePipeline := simplifiedInstallerBootISOTreePipeline(imgPipelineName, kernelVer, rng)
 
 	pipelines = append(pipelines, *installerTreePipeline, *efibootTreePipeline, *bootISOTreePipeline)
 	pipelines = append(pipelines, *bootISOPipeline(t.Filename(), d.isolabelTmpl, t.Arch().Name(), false))
@@ -701,7 +701,7 @@ func edgeSimplifiedInstallerPipelines(t *imageType, customizations *blueprint.Cu
 	return pipelines, nil
 }
 
-func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string) *osbuild.Pipeline {
+func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string, rng *rand.Rand) *osbuild.Pipeline {
 	p := new(osbuild.Pipeline)
 	p.Name = "bootiso-tree"
 	p.Build = "name:build"
@@ -741,6 +741,7 @@ func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string) *o
 				Payload: &disk.Filesystem{
 					Type:       "vfat",
 					Mountpoint: "/",
+					UUID:       disk.NewVolIDFromRand(rng),
 				},
 			},
 		},

internal/distro/rhel90/pipelines.go

@@ -692,10 +692,7 @@ func edgeSimplifiedInstallerPipelines(t *imageType, customizations *blueprint.Cu
 	installerTreePipeline := simplifiedInstallerTreePipeline(repos, installerPackages, kernelVer, archName, d.product, d.osVersion, "edge", customizations.GetFDO())
 	isolabel := fmt.Sprintf(d.isolabelTmpl, archName)
 	efibootTreePipeline := simplifiedInstallerEFIBootTreePipeline(installDevice, kernelVer, archName, d.vendor, d.product, d.osVersion, isolabel, customizations.GetFDO())
-	bootISOTreePipeline, err := simplifiedInstallerBootISOTreePipeline(imgPipelineName, kernelVer, rng)
+	bootISOTreePipeline := simplifiedInstallerBootISOTreePipeline(imgPipelineName, kernelVer, rng)
-	if err != nil {
-		return nil, err
-	}
 
 	pipelines = append(pipelines, *installerTreePipeline, *efibootTreePipeline, *bootISOTreePipeline)
 	pipelines = append(pipelines, *bootISOPipeline(t.Filename(), d.isolabelTmpl, t.Arch().Name(), false))
@@ -703,7 +700,7 @@ func edgeSimplifiedInstallerPipelines(t *imageType, customizations *blueprint.Cu
 	return pipelines, nil
 }
 
-func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string, rng *rand.Rand) (*osbuild.Pipeline, error) {
+func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string, rng *rand.Rand) *osbuild.Pipeline {
 	p := new(osbuild.Pipeline)
 	p.Name = "bootiso-tree"
 	p.Build = "name:build"
@@ -733,11 +730,6 @@ func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string, rn
 		},
 	))
 
-	// TODO: handle error
-	volid, err := disk.NewRandomVolIDFromReader(rng)
-	if err != nil {
-		return nil, err
-	}
 	pt := disk.PartitionTable{
 		Size: 20971520,
 		Partitions: []disk.Partition{
@@ -747,7 +739,7 @@ func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string, rn
 				Payload: &disk.Filesystem{
 					Type:       "vfat",
 					Mountpoint: "/",
-					UUID:       volid,
+					UUID:       disk.NewVolIDFromRand(rng),
 				},
 			},
 		},
@@ -798,7 +790,7 @@ func simplifiedInstallerBootISOTreePipeline(archivePipelineName, kver string, rn
 		copyInputs,
 	))
 
-	return p, nil
+	return p
 }
 
 func simplifiedInstallerEFIBootTreePipeline(installDevice, kernelVer, arch, vendor, product, osVersion, isolabel string, fdo *blueprint.FDOCustomization) *osbuild.Pipeline {

test/data/manifests/centos_8-aarch64-edge_simplified_installer-boot.json

@@ -1315,7 +1315,7 @@
           {
             "type": "org.osbuild.mkfs.fat",
             "options": {
-              "volid": ""
+              "volid": "a178892e"
             },
             "devices": {
               "device": {

test/data/manifests/centos_8-x86_64-edge_simplified_installer-boot.json

@@ -1358,7 +1358,7 @@
           {
             "type": "org.osbuild.mkfs.fat",
             "options": {
-              "volid": ""
+              "volid": "a178892e"
             },
             "devices": {
               "device": {

test/data/manifests/rhel_86-aarch64-edge_simplified_installer-boot.json

@@ -1312,7 +1312,7 @@
           {
             "type": "org.osbuild.mkfs.fat",
             "options": {
-              "volid": ""
+              "volid": "a178892e"
             },
             "devices": {
               "device": {

test/data/manifests/rhel_86-x86_64-edge_simplified_installer-boot.json

@@ -1355,7 +1355,7 @@
           {
             "type": "org.osbuild.mkfs.fat",
             "options": {
-              "volid": ""
+              "volid": "a178892e"
             },
             "devices": {
               "device": {