Split grub config into small tasks

The way boot options for linux and config params for grub
were configured gave rise to quite a few bugs.
The configuration has now been abstracted so that
options can be added without interfering with the work
of other tasks (no more sed_i!)

CHANGELOG.rst

@@ -6,6 +6,7 @@ Changelog
 ----------
 Anders Ingemann
     * Disable persistent network interface names for >=stretch
+    * grub defaults and linux boot options are now easier to configure
 
 2016-06-02
 ----------

bootstrapvz/common/task_groups.py

@@ -152,14 +152,22 @@ def get_locale_group(manifest):
 
 def get_bootloader_group(manifest):
     from bootstrapvz.common.releases import jessie
+    from bootstrapvz.common.releases import stretch
     group = []
     if manifest.system['bootloader'] == 'grub':
         group.extend([grub.AddGrubPackage,
-                      grub.ConfigureGrub])
+                      grub.InitGrubConfig,
+                      grub.SetGrubTerminalToConsole,
+                      grub.SetGrubConsolOutputDeviceToSerial,
+                      grub.RemoveGrubTimeout,
+                      grub.DisableGrubRecovery,
+                      grub.WriteGrubConfig])
         if manifest.release < jessie:
             group.append(grub.InstallGrub_1_99)
         else:
             group.append(grub.InstallGrub_2)
+        if manifest.release >= stretch:
+            group.append(grub.DisablePNIN)
     if manifest.system['bootloader'] == 'extlinux':
         group.append(extlinux.AddExtlinuxPackage)
         if manifest.release < jessie:

bootstrapvz/common/tasks/grub.py

@@ -1,4 +1,5 @@
 from bootstrapvz.base import Task
+from ..exceptions import TaskError
 from .. import phases
 from ..tools import log_check_call
 import filesystem
@@ -16,32 +17,273 @@ class AddGrubPackage(Task):
         info.packages.add('grub-pc')
 
 
-class ConfigureGrub(Task):
+class InitGrubConfig(Task):
-    description = 'Configuring grub'
+    description = 'Initializing grub standard configuration'
+    phase = phases.preparation
+
+    @classmethod
+    def run(cls, info):
+        # The default values and documentation below was fetched from
+        # https://www.gnu.org/software/grub/manual/html_node/Simple-configuration.html
+        # Some explanations have been shortened
+        info.grub_config = {
+            # The default menu entry. This may be a number, in which case it identifies the Nth entry
+            # in the generated menu counted from zero, or the title of a menu entry,
+            # or the special string `saved'. Using the title may be useful if you want to set a menu entry
+            # as the default even though there may be a variable number of entries before it.
+            # If you set this to `saved', then the default menu entry will be that
+            # saved by `GRUB_SAVEDEFAULT', grub-set-default, or grub-reboot.
+            # The default is `0'.
+            'GRUB_DEFAULT': 0,
+
+            # If this option is set to `true', then, when an entry is selected,
+            # save it as a new default entry for use by future runs of GRUB.
+            # This is only useful if `GRUB_DEFAULT=saved';
+            # it is a separate option because `GRUB_DEFAULT=saved' is useful without this option,
+            # in conjunction with grub-set-default or grub-reboot. Unset by default.
+            'GRUB_SAVEDEFAULT': None,
+
+            # Boot the default entry this many seconds after the menu is displayed, unless a key is pressed.
+            # The default is `5'. Set to `0' to boot immediately without displaying the menu,
+            # or to `-1' to wait indefinitely.
+            'GRUB_TIMEOUT': 5,
+
+            # Wait this many seconds for a key to be pressed before displaying the menu.
+            # If no key is pressed during that time, display the menu for the number of seconds specified
+            # in GRUB_TIMEOUT before booting the default entry.
+            # We expect that most people who use GRUB_HIDDEN_TIMEOUT will want to have GRUB_TIMEOUT set to `0'
+            # so that the menu is not displayed at all unless a key is pressed. Unset by default.
+            'GRUB_HIDDEN_TIMEOUT': None,
+
+            # In conjunction with `GRUB_HIDDEN_TIMEOUT', set this to `true' to suppress the verbose countdown
+            # while waiting for a key to be pressed before displaying the menu. Unset by default.
+            'GRUB_HIDDEN_TIMEOUT_QUIET': None,
+
+            # Variants of the corresponding variables without the `_BUTTON' suffix,
+            # used to support vendor-specific power buttons. See Vendor power-on keys.
+            'GRUB_DEFAULT_BUTTON': None,
+            'GRUB_TIMEOUT_BUTTON': None,
+            'GRUB_HIDDEN_TIMEOUT_BUTTON': None,
+            'GRUB_BUTTON_CMOS_ADDRESS': None,
+
+            # Set by distributors of GRUB to their identifying name.
+            # This is used to generate more informative menu entry titles.
+            'GRUB_DISTRIBUTOR': None,
+
+            # Select the terminal input device. You may select multiple devices here, separated by spaces.
+            # Valid terminal input names depend on the platform, but may include
+            # `console' (PC BIOS and EFI consoles),
+            # `serial' (serial terminal),
+            # `ofconsole' (Open Firmware console),
+            # `at_keyboard' (PC AT keyboard, mainly useful with Coreboot),
+            # or `usb_keyboard' (USB keyboard using the HID Boot Protocol,
+            # for cases where the firmware does not handle this).
+            # The default is to use the platform's native terminal input.
+            'GRUB_TERMINAL_INPUT': None,
+
+            # Select the terminal output device. You may select multiple devices here, separated by spaces.
+            # Valid terminal output names depend on the platform, but may include
+            # `console' (PC BIOS and EFI consoles),
+            # `serial' (serial terminal),
+            # `gfxterm' (graphics-mode output),
+            # `ofconsole' (Open Firmware console),
+            # or `vga_text' (VGA text output, mainly useful with Coreboot).
+            # The default is to use the platform's native terminal output.
+            'GRUB_TERMINAL_OUTPUT': None,
+
+            # If this option is set, it overrides both `GRUB_TERMINAL_INPUT' and `GRUB_TERMINAL_OUTPUT'
+            # to the same value.
+            'GRUB_TERMINAL': None,
+
+            # A command to configure the serial port when using the serial console.
+            # See serial. Defaults to `serial'.
+            'GRUB_SERIAL_COMMAND': 'serial',
+
+            # Command-line arguments to add to menu entries for the Linux kernel.
+            'GRUB_CMDLINE_LINUX': [],
+
+            # Unless `GRUB_DISABLE_RECOVERY' is set to `true',
+            # two menu entries will be generated for each Linux kernel:
+            # one default entry and one entry for recovery mode.
+            # This option lists command-line arguments to add only to the default menu entry,
+            # after those listed in `GRUB_CMDLINE_LINUX'.
+            'GRUB_CMDLINE_LINUX_DEFAULT': [],
+
+            # As `GRUB_CMDLINE_LINUX' and `GRUB_CMDLINE_LINUX_DEFAULT', but for NetBSD.
+            'GRUB_CMDLINE_NETBSD': [],
+            'GRUB_CMDLINE_NETBSD_DEFAULT': [],
+
+            # As `GRUB_CMDLINE_LINUX', but for GNU Mach.
+            'GRUB_CMDLINE_GNUMACH': [],
+
+            # The values of these options are appended to the values of
+            # `GRUB_CMDLINE_LINUX' and `GRUB_CMDLINE_LINUX_DEFAULT'
+            # for Linux and Xen menu entries.
+            'GRUB_CMDLINE_XEN': [],
+            'GRUB_CMDLINE_XEN_DEFAULT': [],
+
+            # The values of these options replace the values of
+            # `GRUB_CMDLINE_LINUX' and `GRUB_CMDLINE_LINUX_DEFAULT' for Linux and Xen menu entries.
+            'GRUB_CMDLINE_LINUX_XEN_REPLACE': [],
+            'GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT': [],
+
+            # Normally, grub-mkconfig will generate menu entries that use
+            # universally-unique identifiers (UUIDs) to identify the root filesystem to the Linux kernel,
+            # using a `root=UUID=...' kernel parameter. This is usually more reliable,
+            # but in some cases it may not be appropriate.
+            # To disable the use of UUIDs, set this option to `true'.
+            'GRUB_DISABLE_LINUX_UUID': None,
+
+            # If this option is set to `true', disable the generation of recovery mode menu entries.
+            'GRUB_DISABLE_RECOVERY': None,
+
+            # If graphical video support is required, either because the `gfxterm' graphical terminal is
+            # in use or because `GRUB_GFXPAYLOAD_LINUX' is set,
+            # then grub-mkconfig will normally load all available GRUB video drivers and
+            # use the one most appropriate for your hardware.
+            # If you need to override this for some reason, then you can set this option.
+            # After grub-install has been run, the available video drivers are listed in /boot/grub/video.lst.
+            'GRUB_VIDEO_BACKEND': None,
+
+            # Set the resolution used on the `gfxterm' graphical terminal.
+            # Note that you can only use modes which your graphics card supports
+            # via VESA BIOS Extensions (VBE), so for example native LCD panel resolutions
+            # may not be available.
+            # The default is `auto', which tries to select a preferred resolution. See gfxmode.
+            'GRUB_GFXMODE': 'auto',
+
+            # Set a background image for use with the `gfxterm' graphical terminal.
+            # The value of this option must be a file readable by GRUB at boot time,
+            # and it must end with .png, .tga, .jpg, or .jpeg.
+            # The image will be scaled if necessary to fit the screen.
+            'GRUB_BACKGROUND': None,
+
+            # Set a theme for use with the `gfxterm' graphical terminal.
+            'GRUB_THEME': None,
+
+            # Set to `text' to force the Linux kernel to boot in normal text mode,
+            # `keep' to preserve the graphics mode set using `GRUB_GFXMODE',
+            # `widthxheight'[`xdepth'] to set a particular graphics mode,
+            # or a sequence of these separated by commas or semicolons to try several modes in sequence.
+            # See gfxpayload.
+            # Depending on your kernel, your distribution, your graphics card, and the phase of the moon,
+            # note that using this option may cause GNU/Linux to suffer from various display problems,
+            # particularly during the early part of the boot sequence.
+            # If you have problems, set this option to `text' and GRUB will
+            # tell Linux to boot in normal text mode.
+            'GRUB_GFXPAYLOAD_LINUX': None,
+
+            # Normally, grub-mkconfig will try to use the external os-prober program, if installed,
+            # to discover other operating systems installed on the same system and generate appropriate
+            # menu entries for them. Set this option to `true' to disable this.
+            'GRUB_DISABLE_OS_PROBER': None,
+
+            # Play a tune on the speaker when GRUB starts.
+            # This is particularly useful for users unable to see the screen.
+            # The value of this option is passed directly to play.
+            'GRUB_INIT_TUNE': None,
+
+            # If this option is set, GRUB will issue a badram command to filter out specified regions of RAM.
+            'GRUB_BADRAM': None,
+
+            # This option may be set to a list of GRUB module names separated by spaces.
+            # Each module will be loaded as early as possible, at the start of grub.cfg.
+            'GRUB_PRELOAD_MODULES': [],
+        }
+
+
+class WriteGrubConfig(Task):
+    description = 'Writing grub defaults configuration'
     phase = phases.system_modification
 
     @classmethod
     def run(cls, info):
-        from bootstrapvz.common.releases import stretch
+        grub_config_contents = ''
-        from bootstrapvz.common.tools import sed_i
+        for key, value in info.grub_config.items():
-        grub_def = os.path.join(info.root, 'etc/default/grub')
+            if value is None:
-        if info.manifest.release >= stretch:
+                continue
-            # Disable "Predictable Network Interface Names"
+            if isinstance(value, str):
-            # See issue #245 for more details
+                grub_config_contents += '{}="{}"\n'.format(key, value)
-            sed_i(grub_def, '^GRUB_CMDLINE_LINUX=""', 'GRUB_CMDLINE_LINUX="net.ifnames=0 biosdevname=0"')
+                continue
-        sed_i(grub_def, '^#GRUB_TERMINAL=console', 'GRUB_TERMINAL=console')
+            if isinstance(value, int):
-        sed_i(grub_def, '^GRUB_CMDLINE_LINUX_DEFAULT="quiet"',
+                grub_config_contents += '{}={}\n'.format(key, value)
-                        'GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0"')
+                continue
-        sed_i(grub_def, '^GRUB_TIMEOUT=[0-9]+', 'GRUB_TIMEOUT=0\n'
+            if isinstance(value, bool):
-                                                'GRUB_HIDDEN_TIMEOUT=0\n'
+                grub_config_contents += '{}="{}"\n'.format(key, str(value).lower())
-                                                'GRUB_HIDDEN_TIMEOUT_QUIET=true')
+                continue
-        sed_i(grub_def, '^#GRUB_DISABLE_RECOVERY="true"', 'GRUB_DISABLE_RECOVERY="true"')
+            if isinstance(value, list):
+                if len(value) == 0:
+                    continue
+                args_list = ' '.join(map(str, value))
+                grub_config_contents += '{}="{}"\n'.format(key, args_list)
+                continue
+            raise TaskError('Don\'t know how to handle type {}, '
+                            'when creating grub config'.format(type(value)))
+        grub_defaults = os.path.join(info.root, 'etc/default/grub')
+        with open(grub_defaults, 'w') as grub_defaults_handle:
+            grub_defaults_handle.write(grub_config_contents)
+
+
+class DisablePNIN(Task):
+    description = 'Disabling Predictable Network Interfaces'
+    phase = phases.system_modification
+    successors = [WriteGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        # See issue #245 for more details
+        info.grub_config['GRUB_CMDLINE_LINUX'].append('net.ifnames=0')
+        info.grub_config['GRUB_CMDLINE_LINUX'].append('biosdevname=0')
+
+
+class SetGrubTerminalToConsole(Task):
+    description = 'Setting the grub terminal to `console\''
+    phase = phases.system_modification
+    successors = [WriteGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        # See issue #245 for more details
+        info.grub_config['TERMINAL'] = 'console'
+
+
+class SetGrubConsolOutputDeviceToSerial(Task):
+    description = 'Setting the grub terminal output device to `ttyS0\''
+    phase = phases.system_modification
+    successors = [WriteGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        # See issue #245 for more details
+        info.grub_config['GRUB_CMDLINE_LINUX_DEFAULT'].append('console=ttyS0')
+
+
+class RemoveGrubTimeout(Task):
+    description = 'Setting grub menu timeout to 0'
+    phase = phases.system_modification
+    successors = [WriteGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        info.grub_config['GRUB_TIMEOUT'] = 0
+        info.grub_config['GRUB_HIDDEN_TIMEOUT'] = 0
+        info.grub_config['GRUB_HIDDEN_TIMEOUT_QUIET'] = True
+
+
+class DisableGrubRecovery(Task):
+    description = 'Disabling the grub recovery menu entry'
+    phase = phases.system_modification
+    successors = [WriteGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        info.grub_config['GRUB_DISABLE_RECOVERY'] = True
 
 
 class InstallGrub_1_99(Task):
     description = 'Installing grub 1.99'
     phase = phases.system_modification
-    predecessors = [filesystem.FStab, ConfigureGrub]
+    predecessors = [filesystem.FStab, WriteGrubConfig]
 
     @classmethod
     def run(cls, info):
@@ -83,7 +325,7 @@ class InstallGrub_1_99(Task):
 class InstallGrub_2(Task):
     description = 'Installing grub 2'
     phase = phases.system_modification
-    predecessors = [filesystem.FStab, ConfigureGrub]
+    predecessors = [filesystem.FStab, WriteGrubConfig]
     # Make sure the kernel image is updated after we have installed the bootloader
     successors = [kernel.UpdateInitramfs]
 

bootstrapvz/plugins/docker_daemon/tasks.py

@@ -4,7 +4,6 @@ from bootstrapvz.common.tasks import grub
 from bootstrapvz.common.tasks import initd
 from bootstrapvz.common.tools import log_check_call
 from bootstrapvz.common.tools import sed_i
-from bootstrapvz.providers.gce.tasks import boot as gceboot
 import os
 import os.path
 import shutil
@@ -61,15 +60,13 @@ class AddDockerInit(Task):
 
 
 class EnableMemoryCgroup(Task):
-    description = 'Change grub configuration to enable the memory cgroup'
+    description = 'Enable the memory cgroup in the grub config'
     phase = phases.system_modification
-    successors = [grub.InstallGrub_1_99, grub.InstallGrub_2]
+    successors = [grub.WriteGrubConfig]
-    predecessors = [grub.ConfigureGrub, gceboot.ConfigureGrub]
 
     @classmethod
     def run(cls, info):
-        grub_config = os.path.join(info.root, 'etc/default/grub')
+        info.grub_config['GRUB_CMDLINE_LINUX'].append('cgroup_enable=memory')
-        sed_i(grub_config, r'^(GRUB_CMDLINE_LINUX*=".*)"\s*$', r'\1 cgroup_enable=memory"')
 
 
 class PullDockerImages(Task):

bootstrapvz/providers/azure/__init__.py

@@ -6,6 +6,7 @@ from bootstrapvz.common.tasks import loopback
 from bootstrapvz.common.tasks import initd
 from bootstrapvz.common.tasks import ssh
 from bootstrapvz.common.tasks import apt
+from bootstrapvz.common.tasks import grub
 
 
 def validate_manifest(data, validator, error):
@@ -29,6 +30,7 @@ def resolve_tasks(taskset, manifest):
                     tasks.boot.ConfigureGrub,
                     tasks.boot.PatchUdev,
                     ])
+    taskset.discard(grub.SetGrubConsolOutputDeviceToSerial)
 
 
 def resolve_rollback_tasks(taskset, manifest, completed, counter_task):

bootstrapvz/providers/azure/tasks/boot.py

@@ -23,14 +23,13 @@ class PatchUdev(Task):
 class ConfigureGrub(Task):
     description = 'Change grub configuration to allow for ttyS0 output'
     phase = phases.system_modification
-    predecessors = [grub.ConfigureGrub]
+    successors = [grub.WriteGrubConfig]
-    successors = [grub.InstallGrub_1_99, grub.InstallGrub_2]
 
     @classmethod
     def run(cls, info):
-        from bootstrapvz.common.tools import sed_i
+        info.grub_config['GRUB_CMDLINE_LINUX'].extend([
-        grub_config = os.path.join(info.root, 'etc/default/grub')
+            'console=tty0',
-        sed_i(grub_config, r'^(GRUB_CMDLINE_LINUX_DEFAULT=.*)', r'GRUB_CMDLINE_LINUX_DEFAULT=""')
+            'console=ttyS0,115200n8',
-        sed_i(grub_config, r'^(GRUB_CMDLINE_LINUX*=".*)"\s*$', r'\1console=tty0 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300"')
+            'earlyprintk=ttyS0,115200',
-        sed_i(grub_config, r'^(GRUB_HIDDEN_TIMEOUT=).*', r'#GRUB_HIDDEN_TIMEOUT=true')
+            'rootdelay=300',
-        sed_i(grub_config, r'^.*(GRUB_TIMEOUT=).*$', r'GRUB_TIMEOUT=5')
+        ])

bootstrapvz/providers/ec2/__init__.py

@@ -93,7 +93,16 @@ def resolve_tasks(taskset, manifest):
 
     if manifest.system['bootloader'] == 'pvgrub':
         taskset.add(grub.AddGrubPackage)
-        taskset.add(tasks.boot.ConfigurePVGrub)
+        taskset.update([grub.AddGrubPackage,
+                        grub.InitGrubConfig,
+                        grub.SetGrubTerminalToConsole,
+                        grub.RemoveGrubTimeout,
+                        grub.DisableGrubRecovery,
+                        tasks.boot.CreatePVGrubCustomRule,
+                        tasks.boot.ConfigurePVGrub,
+                        grub.WriteGrubConfig,
+                        tasks.boot.UpdateGrubConfig,
+                        tasks.boot.LinkGrubConfig])
 
     if manifest.volume['backing'].lower() == 'ebs':
         taskset.update([tasks.host.GetInstanceMetadata,

bootstrapvz/providers/ec2/tasks/boot.py

@@ -1,19 +1,29 @@
 from bootstrapvz.base import Task
 from bootstrapvz.common import phases
+from bootstrapvz.common.tasks import grub
 from . import assets
 import os
+from bootstrapvz.common.tools import log_check_call
 
 
-class ConfigurePVGrub(Task):
+class UpdateGrubConfig(Task):
-    description = 'Creating grub config files for PVGrub'
+    description = 'Updating the grub config'
     phase = phases.system_modification
+    successors = [grub.WriteGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        log_check_call(['chroot', info.root, 'update-grub'])
+
+
+class CreatePVGrubCustomRule(Task):
+    description = 'Creating special rule for PVGrub'
+    phase = phases.system_modification
+    successors = [UpdateGrubConfig]
 
     @classmethod
     def run(cls, info):
         import stat
-        rwxr_xr_x = (stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR |
-                     stat.S_IRGRP                | stat.S_IXGRP |
-                     stat.S_IROTH                | stat.S_IXOTH)
         x_all = stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH
 
         grubd = os.path.join(info.root, 'etc/grub.d')
@@ -24,7 +34,7 @@ class ConfigurePVGrub(Task):
         script_src = os.path.join(assets, 'grub.d/40_custom')
         script_dst = os.path.join(info.root, 'etc/grub.d/40_custom')
         copy(script_src, script_dst)
-        os.chmod(script_dst, rwxr_xr_x)
+        os.chmod(script_dst, 0755)
 
         from bootstrapvz.base.fs.partitionmaps.none import NoPartitions
         if not isinstance(info.volume.partition_map, NoPartitions):
@@ -39,14 +49,27 @@ class ConfigurePVGrub(Task):
             from bootstrapvz.common.tools import sed_i
             sed_i(script_dst, '^GRUB_DEVICE=/dev/xvda$', 'GRUB_DEVICE=/dev/xvda1')
 
-        from bootstrapvz.common.tools import sed_i
-        grub_def = os.path.join(info.root, 'etc/default/grub')
-        sed_i(grub_def, '^GRUB_TIMEOUT=[0-9]+', 'GRUB_TIMEOUT=0\n'
-                                                'GRUB_HIDDEN_TIMEOUT=true')
-        sed_i(grub_def, '^#GRUB_TERMINAL=console', 'GRUB_TERMINAL=console')
-        sed_i(grub_def, '^GRUB_CMDLINE_LINUX_DEFAULT=.*', 'GRUB_CMDLINE_LINUX_DEFAULT="consoleblank=0 console=hvc0 elevator=noop"')
 
-        from bootstrapvz.common.tools import log_check_call
+class ConfigurePVGrub(Task):
-        log_check_call(['chroot', info.root, 'update-grub'])
+    description = 'Configuring PVGrub'
+    phase = phases.system_modification
+    successors = [UpdateGrubConfig]
+
+    @classmethod
+    def run(cls, info):
+        info.grub_config['GRUB_CMDLINE_LINUX'].extend([
+            'consoleblank=0',
+            'console=hvc0',
+            'elevator=noop',
+        ])
+
+
+class LinkGrubConfig(Task):
+    description = 'Linking the grub config to /boot/grub/menu.lst'
+    phase = phases.system_modification
+    predecessors = [UpdateGrubConfig]
+
+    @classmethod
+    def run(cls, info):
         log_check_call(['chroot', info.root,
                         'ln', '--symbolic', '/boot/grub/grub.cfg', '/boot/grub/menu.lst'])

bootstrapvz/providers/gce/__init__.py

@@ -12,6 +12,7 @@ from bootstrapvz.common.tasks import loopback
 from bootstrapvz.common.tasks import initd
 from bootstrapvz.common.tasks import ssh
 from bootstrapvz.common.tasks import volume
+from bootstrapvz.common.tasks import grub
 
 
 def validate_manifest(data, validator, error):
@@ -43,6 +44,7 @@ def resolve_tasks(taskset, manifest):
                     tasks.image.CreateTarball,
                     volume.Delete,
                     ])
+    taskset.discard(grub.SetGrubConsolOutputDeviceToSerial)
 
     if 'gcs_destination' in manifest.provider:
         taskset.add(tasks.image.UploadImage)

bootstrapvz/providers/gce/tasks/boot.py

@@ -1,17 +1,14 @@
 from bootstrapvz.base import Task
 from bootstrapvz.common import phases
 from bootstrapvz.common.tasks import grub
-import os.path
 
 
 class ConfigureGrub(Task):
     description = 'Change grub configuration to allow for ttyS0 output'
     phase = phases.system_modification
-    successors = [grub.InstallGrub_1_99, grub.InstallGrub_2]
+    successors = [grub.WriteGrubConfig]
 
     @classmethod
     def run(cls, info):
-        from bootstrapvz.common.tools import sed_i
+        info.grub_config['GRUB_CMDLINE_LINUX'].append('console=ttyS0,38400n8')
-        grub_config = os.path.join(info.root, 'etc/default/grub')
+        info.grub_config['GRUB_CMDLINE_LINUX'].append('elevator=noop')
-        sed_i(grub_config, r'^(GRUB_CMDLINE_LINUX*=".*)"\s*$', r'\1console=ttyS0,38400n8 elevator=noop"')
-        sed_i(grub_config, r'^.*(GRUB_TIMEOUT=).*$', r'GRUB_TIMEOUT=0')