If booster fails to find root fs then print missing modules

Issue: #242

Author: anatol

docs/manpage.md

@@ -52,6 +52,8 @@ Booster advantages:
 
  * `modules_force_load` list of module names that are forcibly loaded during the boot process before switching into user-space. Any module in this list automatically added to the image so there is no need to duplicate it at `modules` property.
 
+ * `append_all_modaliases` is a boolean flag that instructs booster to add all hosts's module aliases to the booster image. This flag is useful for debugging boot timeout issues when some important modules are missed from the image. Setting the flag to `true` will help to print module names for aliases that were requested by kernel but missed in the image.
+
  * `compression` is a flag that specifies compression for the output initramfs file. Currently supported algorithms are "zstd", "gzip", "xz", "lz4", "none". If no option specified then "zstd" is used as a default compression.
 
  * `mount_timeout` timeout for waiting for the root filesystem to appear. The field format is a decimal number and then unit number. Valid units are "s", "m", "h". If no value specified then default timeout (3 minutes) is used. To disable the timeout completely specify "0s".
@@ -204,6 +206,8 @@ Regenerate the initramfs and reboot. Once inside busybox, get the logs and send
 
 The logs will be in `/srv/atftp` on the server.
 
+### Boot timeout
+If you got `booster: Timeout waiting for root filesystem` error please add `append_all_modaliases` config flag and rebuild the image. With this flag you'll get a list of modules that were requested by the kernel but absent in the booster image. Some of these modules might be required to boot your system.
 
 ## EXAMPLES
 Create an initramfs file specific for the current kernel/host. The output file is booster.img:

generator/config.go

@@ -27,11 +27,12 @@ type UserConfig struct {
 	Universal            bool   `yaml:",omitempty"`
 	Modules              string `yaml:",omitempty"`                   // comma separated list of extra modules to add to initramfs
 	ModulesForceLoad     string `yaml:"modules_force_load,omitempty"` // comma separated list of extra modules to load at the boot time
-	Compression          string `yaml:",omitempty"`                   // output file compression
-	MountTimeout         string `yaml:"mount_timeout,omitempty"`      // timeout for waiting for the rootfs mounted
-	ExtraFiles           string `yaml:"extra_files,omitempty"`        // comma-separated list of files to add to image
-	StripBinaries        bool   `yaml:"strip,omitempty"`              // if strip symbols from the binaries, shared libraries and kernel modules
-	EnableVirtualConsole bool   `yaml:"vconsole,omitempty"`           // configure virtual console at boot time using config from https://www.freedesktop.org/software/systemd/man/vconsole.conf.html
+	AppendAllModAliases  bool   `yaml:"append_all_modaliases,omitempty"`
+	Compression          string `yaml:",omitempty"`              // output file compression
+	MountTimeout         string `yaml:"mount_timeout,omitempty"` // timeout for waiting for the rootfs mounted
+	ExtraFiles           string `yaml:"extra_files,omitempty"`   // comma-separated list of files to add to image
+	StripBinaries        bool   `yaml:"strip,omitempty"`         // if strip symbols from the binaries, shared libraries and kernel modules
+	EnableVirtualConsole bool   `yaml:"vconsole,omitempty"`      // configure virtual console at boot time using config from https://www.freedesktop.org/software/systemd/man/vconsole.conf.html
 	EnableLVM            bool   `yaml:"enable_lvm"`
 	EnableMdraid         bool   `yaml:"enable_mdraid"`
 	MdraidConfigPath     string `yaml:"mdraid_config_path"`
@@ -142,6 +143,7 @@ func readGeneratorConfig(file string) (*generatorConfig, error) {
 	conf.readDeviceAliases = readDeviceAliases
 	conf.readHostModules = readHostModules
 	conf.readModprobeOptions = readModprobeOptions
+	conf.appendAllModAliases = u.AppendAllModAliases
 	conf.stripBinaries = u.StripBinaries || opts.BuildCommand.Strip
 	conf.enableLVM = u.EnableLVM
 	conf.enableMdraid = u.EnableMdraid

generator/generator.go

@@ -21,6 +21,7 @@ type generatorConfig struct {
 	universal               bool
 	modules                 []string // extra modules to add
 	modulesForceLoad        []string // extra modules to load at the boot time
+	appendAllModAliases     bool
 	compression             string
 	timeout                 time.Duration
 	extraFiles              []string
@@ -214,10 +215,15 @@ func generateInitRamfs(conf *generatorConfig) error {
 		return err
 	}
 
-	// collect aliases for required modules only
-	aliases, err := kmod.filterAliasesForRequiredModules(conf)
-	if err != nil {
-		return err
+	var aliases []alias
+	if conf.appendAllModAliases {
+		aliases = kmod.aliases
+	} else {
+		// collect aliases for required modules only
+		aliases, err = kmod.filterAliasesForRequiredModules(conf)
+		if err != nil {
+			return err
+		}
 	}
 	if err := img.appendAliasesFile(aliases); err != nil {
 		return err

init/main.go

@@ -47,6 +47,8 @@ var (
 	rootRo, rootRw bool
 
 	zfsDataset string
+
+	errRootMountTimeout = fmt.Errorf("Timeout waiting for root filesystem")
 )
 
 type set map[string]bool
@@ -858,7 +860,7 @@ func boost() error {
 		// TODO: cancellable, timeout context?
 		timeout := waitTimeout(&rootMounted, time.Duration(config.MountTimeout)*time.Second)
 		if timeout {
-			return fmt.Errorf("Timeout waiting for root filesystem")
+			return errRootMountTimeout
 		}
 	} else {
 		// wait for mount forever
@@ -991,6 +993,22 @@ func reboot() {
 	_ = unix.Reboot(unix.LINUX_REBOOT_CMD_RESTART)
 }
 
+func printMissingModules() {
+	missingModulesMutex.Lock()
+	defer missingModulesMutex.Unlock()
+
+	if len(missingModules) == 0 {
+		return
+	}
+
+	mods := make([]string, 0, len(missingModules))
+	for k := range missingModules {
+		mods = append(mods, k)
+	}
+
+	warning("Following modules were requested by kernel but not present in the image: [%s]. Please check the list and see if any of the modules required to detect your root filesystem.", strings.Join(mods, " "))
+}
+
 func main() {
 	readStartTime()
 
@@ -1002,6 +1020,10 @@ func main() {
 	if err := boost(); err != nil {
 		// if it does then it indicates some problem
 		severe("%v", err)
+		if errors.Is(err, errRootMountTimeout) {
+			// if we fail to detect the root filesystem maybe we are missing some kernel modules needed for storage devices?
+			printMissingModules()
+		}
 	}
 	emergencyShell()
 

init/module.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bufio"
+	"errors"
 	"os"
 	"path/filepath"
 	"strings"
@@ -17,6 +18,9 @@ var (
 	loadingModules   = make(map[string][]*sync.WaitGroup)
 	loadingModulesWg sync.WaitGroup // total number of modules being loaded
 	modulesMutex     sync.Mutex
+
+	missingModules      = make(map[string]bool) // set of modules that kernel wanted to load via aliases but they were missing in the image
+	missingModulesMutex sync.Mutex
 )
 
 type alias struct{ pattern, module string } // module alias info
@@ -66,6 +70,11 @@ func loadModuleUnlocked(wg *sync.WaitGroup, modules ...string) {
 		depsWg.Wait()
 		if err := finitModule(mod); err != nil {
 			info("finit(%v): %v", mod, err)
+			if errors.Is(err, os.ErrNotExist) {
+				missingModulesMutex.Lock()
+				missingModules[mod] = true
+				missingModulesMutex.Unlock()
+			}
 		}
 
 		modulesMutex.Lock()

tests/integration_test.go

@@ -159,6 +159,20 @@ func TestMountTimeout(t *testing.T) {
 	require.NoError(t, vm.ConsoleExpect("Timeout waiting for root filesystem"))
 }
 
+func TestMountTimeoutWithAllModaliases(t *testing.T) {
+	vm, err := buildVmInstance(t, Opts{
+		kernelArgs:          []string{"root=/dev/sda"},
+		modules:             "-*",
+		mountTimeout:        1,
+		appendAllModAliases: true,
+	})
+	require.NoError(t, err)
+	defer vm.Kill()
+
+	require.NoError(t, vm.ConsoleExpect("Timeout waiting for root filesystem"))
+	require.NoError(t, vm.ConsoleExpect("Following modules were requested by kernel but not present in the image: ["))
+}
+
 func TestFsck(t *testing.T) {
 	vm, err := buildVmInstance(t, Opts{
 		compression: "none",

tests/util.go

@@ -236,6 +236,7 @@ type GeneratorConfig struct {
 	ModulesForceLoad     string         `yaml:"modules_force_load,omitempty"` // comma separated list of extra modules to load at the boot time
 	Compression          string         `yaml:",omitempty"`
 	MountTimeout         string         `yaml:"mount_timeout,omitempty"`
+	AppendAllModAliases  bool           `yaml:"append_all_modaliases,omitempty"`
 	ExtraFiles           string         `yaml:"extra_files,omitempty"`
 	StripBinaries        bool           `yaml:"strip,omitempty"` // strip symbols from the binaries, shared libraries and kernel modules
 	EnableVirtualConsole bool           `yaml:"vconsole,omitempty"`
@@ -265,6 +266,7 @@ func generateBoosterConfig(output string, opts Opts) error {
 	conf.Universal = true
 	conf.Compression = opts.compression
 	conf.MountTimeout = strconv.Itoa(opts.mountTimeout) + "s"
+	conf.AppendAllModAliases = opts.appendAllModAliases
 	conf.ExtraFiles = opts.extraFiles
 	conf.StripBinaries = opts.stripBinaries
 	conf.EnableVirtualConsole = opts.enableVirtualConsole
@@ -305,6 +307,7 @@ type Opts struct {
 	asIso                bool // generate ISO file instead of *.raw
 	scriptEnvvars        []string
 	mountTimeout         int // in seconds
+	appendAllModAliases  bool
 	extraFiles           string
 	stripBinaries        bool
 	enableVirtualConsole bool