[ostree] ostadmin: add update-kernel command to regenerate initramfs and boot config

[Giovanni Campagna <gcampagna src gnome org>]

commit affa5755a6a1b5355a9f9a20b18ab203274eb387
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Mon Aug 13 23:47:23 2012 +0200

    ostadmin: add update-kernel command to regenerate initramfs and boot config
    
    This command regenerates kernel-dependent files. It is meant to
    be run after kernel upgrades in the host distribution, to keep
    the ostree installation running, and attempts to figure out the
    right version automatically (and without changing the ostree checkout)

 Makefile-ostadmin.am                          |    1 +
 src/ostadmin/main.c                           |    1 +
 src/ostadmin/ot-admin-builtin-deploy.c        |  289 +++--------------------
 src/ostadmin/ot-admin-builtin-update-kernel.c |  328 +++++++++++++++++++++++++
 src/ostadmin/ot-admin-builtins.h              |    1 +
 5 files changed, 360 insertions(+), 260 deletions(-)
---
diff --git a/Makefile-ostadmin.am b/Makefile-ostadmin.am
index 16eca42..df22f8b 100644
--- a/Makefile-ostadmin.am
+++ b/Makefile-ostadmin.am
@@ -21,6 +21,7 @@ ostadmin_SOURCES = src/ostadmin/main.c \
 	src/ostadmin/ot-admin-builtins.h \
 	src/ostadmin/ot-admin-builtin-init.c \
 	src/ostadmin/ot-admin-builtin-deploy.c \
+	src/ostadmin/ot-admin-builtin-update-kernel.c \
 	src/ostadmin/ot-admin-main.h \
 	src/ostadmin/ot-admin-main.c \
 	$(NULL)
diff --git a/src/ostadmin/main.c b/src/ostadmin/main.c
index 42d6f21..8a2ded3 100644
--- a/src/ostadmin/main.c
+++ b/src/ostadmin/main.c
@@ -32,6 +32,7 @@
 static OtAdminBuiltin builtins[] = {
   { "deploy", ot_admin_builtin_deploy, 0 },
   { "init", ot_admin_builtin_init, 0 },
+  { "update-kernel", ot_admin_builtin_update_kernel, 0 },
   { NULL }
 };
 
diff --git a/src/ostadmin/ot-admin-builtin-deploy.c b/src/ostadmin/ot-admin-builtin-deploy.c
index 4665889..cc5cae8 100644
--- a/src/ostadmin/ot-admin-builtin-deploy.c
+++ b/src/ostadmin/ot-admin-builtin-deploy.c
@@ -26,255 +26,21 @@
 #include "ostree.h"
 
 #include <glib/gi18n.h>
-#include <sys/utsname.h>
 
 typedef struct {
   OstreeRepo  *repo;
 } OtAdminDeploy;
 
-static gboolean opt_no_initramfs;
-static gboolean opt_no_bootloader;
+static gboolean opt_no_kernel;
 static char *opt_ostree_dir;
 
 static GOptionEntry options[] = {
   { "ostree-dir", 0, 0, G_OPTION_ARG_STRING, &opt_ostree_dir, "Path to OSTree root directory", NULL },
-  { "no-initramfs", 0, 0, G_OPTION_ARG_NONE, &opt_no_initramfs, "Don't generate initramfs", NULL },
-  { "no-bootloader", 0, 0, G_OPTION_ARG_NONE, &opt_no_bootloader, "Don't update bootloader", NULL },
+  { "no-kernel", 0, 0, G_OPTION_ARG_NONE, &opt_no_kernel, "Don't update kernel related config (initramfs, bootloader)", NULL },
   { NULL }
 };
 
 static gboolean
-copy_modules (const char    *release,
-              GCancellable  *cancellable,
-              GError       **error)
-{
-  gboolean ret = FALSE;
-  ot_lobj GFile *src_modules_file = NULL;
-  ot_lobj GFile *dest_modules_parent = NULL;
-  ot_lobj GFile *dest_modules_file = NULL;
-  
-  src_modules_file = ot_gfile_from_build_path ("/lib/modules", release, NULL);
-  dest_modules_file = ot_gfile_from_build_path (opt_ostree_dir, "modules", release, NULL);
-  dest_modules_parent = g_file_get_parent (dest_modules_file);
-  if (!ot_gfile_ensure_directory (dest_modules_parent, FALSE, error))
-    goto out;
-
-  if (!g_file_query_exists (dest_modules_file, cancellable))
-    {
-      if (!ot_gio_shutil_cp_al_or_fallback (src_modules_file, dest_modules_file, cancellable, error))
-        goto out;
-    }
-      
-  ret = TRUE;
- out:
-  if (error)
-    g_prefix_error (error, "Error copying kernel modules: ");
-  return ret;
-}
-
-static gboolean
-update_initramfs (const char       *release,
-                  const char       *deploy_target,
-                  GCancellable     *cancellable,
-                  GError          **error)
-{
-  gboolean ret = FALSE;
-  ot_lfree char *initramfs_name = NULL;
-  ot_lobj GFile *initramfs_file = NULL;
-  ot_lfree char *last_deploy_path = NULL;
-
-  initramfs_name = g_strconcat ("initramfs-ostree-", release, ".img", NULL);
-  initramfs_file = ot_gfile_from_build_path ("/boot", initramfs_name, NULL);
-  if (!g_file_query_exists (initramfs_file, NULL))
-    {
-      ot_lptrarray GPtrArray *mkinitramfs_args = NULL;
-      ot_lobj GFile *tmpdir = NULL;
-      ot_lfree char *initramfs_tmp_path = NULL;
-      ot_lfree char *ostree_vardir = NULL;
-      ot_lfree char *ostree_moduledir = NULL;
-      ot_lobj GFile *initramfs_tmp_file = NULL;
-      ot_lobj GFileInfo *initramfs_tmp_info = NULL;
-          
-      if (!ostree_create_temp_dir (NULL, "ostree-initramfs", NULL, &tmpdir,
-                                   cancellable, error))
-        goto out;
-
-      ostree_vardir = g_build_filename (opt_ostree_dir, "var", NULL);
-      ostree_moduledir = g_build_filename (opt_ostree_dir, "modules", NULL);
-
-      last_deploy_path = g_build_filename (opt_ostree_dir, deploy_target, NULL);
-
-      mkinitramfs_args = g_ptr_array_new ();
-      /* Note: the hardcoded /tmp path below is not actually a
-       * security flaw, because we've bind-mounted dracut's view
-       * of /tmp to the securely-created tmpdir above.
-       */
-      ot_ptrarray_add_many (mkinitramfs_args,
-                            "linux-user-chroot",
-                            "--mount-readonly", "/",
-                            "--mount-proc", "/proc",
-                            "--mount-bind", "/dev", "/dev",
-                            "--mount-bind", ostree_vardir, "/var",
-                            "--mount-bind", ot_gfile_get_path_cached (tmpdir), "/tmp",
-                            "--mount-bind", ostree_moduledir, "/lib/modules",
-                            last_deploy_path,
-                            "dracut", "-f", "/tmp/initramfs-ostree.img", release,
-                            NULL);
-      g_ptr_array_add (mkinitramfs_args, NULL);
-          
-      g_print ("Generating initramfs using %s...\n", last_deploy_path);
-      if (!ot_spawn_sync_checked (NULL, (char**)mkinitramfs_args->pdata, NULL,
-                                  G_SPAWN_SEARCH_PATH,
-                                  NULL, NULL, NULL, NULL, error))
-        goto out;
-          
-      initramfs_tmp_file = g_file_get_child (tmpdir, "initramfs-ostree.img");
-      initramfs_tmp_info = g_file_query_info (initramfs_tmp_file, OSTREE_GIO_FAST_QUERYINFO,
-                                              G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
-                                              cancellable, error);
-      if (!initramfs_tmp_info)
-        goto out;
-
-      if (g_file_info_get_size (initramfs_tmp_info) == 0)
-        {
-          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
-                       "Initramfs generation failed, check dracut.log");
-          goto out;
-        }
-
-      if (!g_file_copy (initramfs_tmp_file, initramfs_file, 0, cancellable, NULL, NULL, error))
-        goto out;
-          
-      g_print ("Created: %s\n", ot_gfile_get_path_cached (initramfs_file));
-
-      (void) ot_gfile_unlink (initramfs_tmp_file, NULL, NULL);
-      (void) rmdir (ot_gfile_get_path_cached (tmpdir));
-    }
-
-  ret = TRUE;
- out:
-  return ret;
-}
-
-static gboolean
-grep_literal (GFile              *f,
-              const char         *string,
-              gboolean           *out_matches,
-              GCancellable       *cancellable,
-              GError            **error)
-{
-  gboolean ret = FALSE;
-  gboolean ret_matches = FALSE;
-  ot_lobj GInputStream *in = NULL;
-  ot_lobj GDataInputStream *datain = NULL;
-  ot_lfree char *line = NULL;
-
-  in = (GInputStream*)g_file_read (f, cancellable, error);
-  if (!in)
-    goto out;
-  datain = (GDataInputStream*)g_data_input_stream_new (in);
-  if (!in)
-    goto out;
-
-  while ((line = g_data_input_stream_read_line (datain, NULL, cancellable, error)) != NULL)
-    {
-      if (strstr (line, string))
-        {
-          ret_matches = TRUE;
-          break;
-        }
-      
-      g_free (line);
-    }
-
-  ret = TRUE;
-  if (out_matches)
-    *out_matches = ret_matches;
- out:
-  return ret;
-}
-
-static gboolean
-get_kernel_path_from_release (const char         *release,
-                              GFile             **out_path,
-                              GCancellable       *cancellable,
-                              GError            **error)
-{
-  gboolean ret = FALSE;
-  ot_lfree char *name = NULL;
-  ot_lobj GFile *possible_path = NULL;
-
-  /* TODO - replace this with grubby code */
-
-  name = g_strconcat ("vmlinuz-", release, NULL);
-  possible_path = ot_gfile_from_build_path ("/boot", name, NULL);
-  if (!g_file_query_exists (possible_path, cancellable))
-    g_clear_object (&possible_path);
-
-  ret = TRUE;
-  ot_transfer_out_value (out_path, &possible_path);
-  /*  out: */
-  return ret;
-}
-
-static gboolean
-update_grub (const char         *release,
-             GCancellable       *cancellable,
-             GError            **error)
-{
-  gboolean ret = FALSE;
-  ot_lobj GFile *grub_path = g_file_new_for_path ("/boot/grub/grub.conf");
-
-  if (g_file_query_exists (grub_path, cancellable))
-    {
-      gboolean have_grub_entry;
-      if (!grep_literal (grub_path, "OSTree", &have_grub_entry,
-                         cancellable, error))
-        goto out;
-
-      if (!have_grub_entry)
-        {
-          ot_lptrarray GPtrArray *grubby_args = NULL;
-          ot_lfree char *add_kernel_arg = NULL;
-          ot_lfree char *initramfs_arg = NULL;
-          ot_lobj GFile *kernel_path = NULL;
-
-          if (!get_kernel_path_from_release (release, &kernel_path, cancellable, error))
-            goto out;
-
-          if (kernel_path == NULL)
-            {
-              g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
-                           "Couldn't find kernel for release %s", release);
-              goto out;
-            }
-
-          grubby_args = g_ptr_array_new ();
-          add_kernel_arg = g_strconcat ("--add-kernel=", ot_gfile_get_path_cached (kernel_path), NULL);
-          initramfs_arg = g_strconcat ("--initrd=", "/boot/initramfs-ostree-", release, ".img", NULL);
-          ot_ptrarray_add_many (grubby_args, "grubby", "--grub", add_kernel_arg, initramfs_arg,
-                                "--copy-default", "--title=OSTree", NULL);
-          g_ptr_array_add (grubby_args, NULL);
-
-          g_print ("Adding OSTree grub entry...\n");
-          if (!ot_spawn_sync_checked (NULL, (char**)grubby_args->pdata, NULL, G_SPAWN_SEARCH_PATH,
-                                      NULL, NULL, NULL, NULL, error))
-            goto out;
-        } 
-      else
-        g_print ("Already have OSTree entry in grub config\n");
-    }
-  else
-    {
-      g_print ("/boot/grub/grub.conf not found, assuming you have GRUB 2\n");
-    }
-  
-  ret = TRUE;
- out:
-  return ret;
-}
-
-static gboolean
 update_current (const char         *deploy_target,
                 GCancellable       *cancellable,
                 GError            **error)
@@ -344,6 +110,31 @@ do_checkout (OtAdminDeploy     *self,
   return ret;
 }
 
+static gboolean
+do_update_kernel (OtAdminDeploy     *self,
+                  const char        *deploy_target,
+                  GCancellable      *cancellable,
+                  GError           **error)
+{
+  gboolean ret = FALSE;
+  ot_lptrarray GPtrArray *args = NULL;
+
+  args = g_ptr_array_new ();
+  ot_ptrarray_add_many (args, "ostadmin", "update-kernel",
+                        "--ostree-dir", opt_ostree_dir,
+                        deploy_target, NULL);
+  g_ptr_array_add (args, NULL);
+
+  if (!ot_spawn_sync_checked (opt_ostree_dir, (char**)args->pdata, NULL, G_SPAWN_SEARCH_PATH,
+                              NULL, NULL, NULL, NULL, error))
+    goto out;
+
+  ret = TRUE;
+ out:
+  return ret;
+}
+
+
 gboolean
 ot_admin_builtin_deploy (int argc, char **argv, GError **error)
 {
@@ -353,8 +144,6 @@ ot_admin_builtin_deploy (int argc, char **argv, GError **error)
   gboolean ret = FALSE;
   const char *deploy_target = NULL;
   const char *revision = NULL;
-  struct utsname utsname;
-  const char *release;
   __attribute__((unused)) GCancellable *cancellable = NULL;
 
   if (!opt_ostree_dir)
@@ -381,32 +170,12 @@ ot_admin_builtin_deploy (int argc, char **argv, GError **error)
   if (!do_checkout (self, deploy_target, revision, cancellable, error))
     goto out;
 
-  (void) uname (&utsname);
-  
-  if (strcmp (utsname.sysname, "Linux") != 0)
-    {
-      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
-                   "Unsupported machine %s", utsname.sysname);
-      goto out;
-    }
-  
-  release = utsname.release;
-  
-  if (!copy_modules (release, cancellable, error))
-    goto out;
-  
-  if (!opt_no_initramfs)
+  if (!opt_no_kernel)
     {
-      if (!update_initramfs (release, deploy_target, cancellable, error))
+      if (!do_update_kernel (self, deploy_target, cancellable, error))
         goto out;
     }
   
-  if (!opt_no_bootloader)
-    {
-      if (!update_grub (release, cancellable, error))
-        goto out;
-    }
-
   if (!update_current (deploy_target, cancellable, error))
     goto out;
 
diff --git a/src/ostadmin/ot-admin-builtin-update-kernel.c b/src/ostadmin/ot-admin-builtin-update-kernel.c
new file mode 100644
index 0000000..dd538ca
--- /dev/null
+++ b/src/ostadmin/ot-admin-builtin-update-kernel.c
@@ -0,0 +1,328 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2012 Colin Walters <walters verbum org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Colin Walters <walters verbum org>
+ */
+
+#include "config.h"
+
+#include "ot-admin-builtins.h"
+#include "ostree.h"
+
+#include <glib/gi18n.h>
+#include <sys/utsname.h>
+
+typedef struct {
+  OstreeRepo  *repo;
+} OtAdminUpdateKernel;
+
+static char *opt_ostree_dir;
+
+static GOptionEntry options[] = {
+  { "ostree-dir", 0, 0, G_OPTION_ARG_STRING, &opt_ostree_dir, "Path to OSTree root directory", NULL },
+  { NULL }
+};
+
+static gboolean
+copy_modules (const char    *release,
+              GCancellable  *cancellable,
+              GError       **error)
+{
+  gboolean ret = FALSE;
+  ot_lobj GFile *src_modules_file = NULL;
+  ot_lobj GFile *dest_modules_parent = NULL;
+  ot_lobj GFile *dest_modules_file = NULL;
+  
+  src_modules_file = ot_gfile_from_build_path ("/lib/modules", release, NULL);
+  dest_modules_file = ot_gfile_from_build_path (opt_ostree_dir, "modules", release, NULL);
+  dest_modules_parent = g_file_get_parent (dest_modules_file);
+  if (!ot_gfile_ensure_directory (dest_modules_parent, FALSE, error))
+    goto out;
+
+  if (!g_file_query_exists (dest_modules_file, cancellable))
+    {
+      if (!ot_gio_shutil_cp_al_or_fallback (src_modules_file, dest_modules_file, cancellable, error))
+        goto out;
+    }
+      
+  ret = TRUE;
+ out:
+  if (error)
+    g_prefix_error (error, "Error copying kernel modules: ");
+  return ret;
+}
+
+static gboolean
+update_initramfs (const char       *release,
+                  const char       *deploy_target,
+                  GCancellable     *cancellable,
+                  GError          **error)
+{
+  gboolean ret = FALSE;
+  ot_lfree char *initramfs_name = NULL;
+  ot_lobj GFile *initramfs_file = NULL;
+  ot_lfree char *last_deploy_path = NULL;
+
+  initramfs_name = g_strconcat ("initramfs-ostree-", release, ".img", NULL);
+  initramfs_file = ot_gfile_from_build_path ("/boot", initramfs_name, NULL);
+  if (!g_file_query_exists (initramfs_file, NULL))
+    {
+      ot_lptrarray GPtrArray *mkinitramfs_args = NULL;
+      ot_lobj GFile *tmpdir = NULL;
+      ot_lfree char *initramfs_tmp_path = NULL;
+      ot_lfree char *ostree_vardir = NULL;
+      ot_lfree char *ostree_moduledir = NULL;
+      ot_lobj GFile *initramfs_tmp_file = NULL;
+      ot_lobj GFileInfo *initramfs_tmp_info = NULL;
+          
+      if (!ostree_create_temp_dir (NULL, "ostree-initramfs", NULL, &tmpdir,
+                                   cancellable, error))
+        goto out;
+
+      ostree_vardir = g_build_filename (opt_ostree_dir, "var", NULL);
+      ostree_moduledir = g_build_filename (opt_ostree_dir, "modules", NULL);
+
+      last_deploy_path = g_build_filename (opt_ostree_dir, deploy_target, NULL);
+
+      mkinitramfs_args = g_ptr_array_new ();
+      /* Note: the hardcoded /tmp path below is not actually a
+       * security flaw, because we've bind-mounted dracut's view
+       * of /tmp to the securely-created tmpdir above.
+       */
+      ot_ptrarray_add_many (mkinitramfs_args,
+                            "linux-user-chroot",
+                            "--mount-readonly", "/",
+                            "--mount-proc", "/proc",
+                            "--mount-bind", "/dev", "/dev",
+                            "--mount-bind", ostree_vardir, "/var",
+                            "--mount-bind", ot_gfile_get_path_cached (tmpdir), "/tmp",
+                            "--mount-bind", ostree_moduledir, "/lib/modules",
+                            last_deploy_path,
+                            "dracut", "-f", "/tmp/initramfs-ostree.img", release,
+                            NULL);
+      g_ptr_array_add (mkinitramfs_args, NULL);
+          
+      g_print ("Generating initramfs using %s...\n", last_deploy_path);
+      if (!ot_spawn_sync_checked (NULL, (char**)mkinitramfs_args->pdata, NULL,
+                                  G_SPAWN_SEARCH_PATH,
+                                  NULL, NULL, NULL, NULL, error))
+        goto out;
+          
+      initramfs_tmp_file = g_file_get_child (tmpdir, "initramfs-ostree.img");
+      initramfs_tmp_info = g_file_query_info (initramfs_tmp_file, OSTREE_GIO_FAST_QUERYINFO,
+                                              G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
+                                              cancellable, error);
+      if (!initramfs_tmp_info)
+        goto out;
+
+      if (g_file_info_get_size (initramfs_tmp_info) == 0)
+        {
+          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                       "Initramfs generation failed, check dracut.log");
+          goto out;
+        }
+
+      if (!g_file_copy (initramfs_tmp_file, initramfs_file, 0, cancellable, NULL, NULL, error))
+        goto out;
+          
+      g_print ("Created: %s\n", ot_gfile_get_path_cached (initramfs_file));
+
+      (void) ot_gfile_unlink (initramfs_tmp_file, NULL, NULL);
+      (void) rmdir (ot_gfile_get_path_cached (tmpdir));
+    }
+
+  ret = TRUE;
+ out:
+  return ret;
+}
+
+static gboolean
+grep_literal (GFile              *f,
+              const char         *string,
+              gboolean           *out_matches,
+              GCancellable       *cancellable,
+              GError            **error)
+{
+  gboolean ret = FALSE;
+  gboolean ret_matches = FALSE;
+  ot_lobj GInputStream *in = NULL;
+  ot_lobj GDataInputStream *datain = NULL;
+  ot_lfree char *line = NULL;
+
+  in = (GInputStream*)g_file_read (f, cancellable, error);
+  if (!in)
+    goto out;
+  datain = (GDataInputStream*)g_data_input_stream_new (in);
+  if (!in)
+    goto out;
+
+  while ((line = g_data_input_stream_read_line (datain, NULL, cancellable, error)) != NULL)
+    {
+      if (strstr (line, string))
+        {
+          ret_matches = TRUE;
+          break;
+        }
+      
+      g_free (line);
+    }
+
+  ret = TRUE;
+  if (out_matches)
+    *out_matches = ret_matches;
+ out:
+  return ret;
+}
+
+static gboolean
+get_kernel_path_from_release (const char         *release,
+                              GFile             **out_path,
+                              GCancellable       *cancellable,
+                              GError            **error)
+{
+  gboolean ret = FALSE;
+  ot_lfree char *name = NULL;
+  ot_lobj GFile *possible_path = NULL;
+
+  /* TODO - replace this with grubby code */
+
+  name = g_strconcat ("vmlinuz-", release, NULL);
+  possible_path = ot_gfile_from_build_path ("/boot", name, NULL);
+  if (!g_file_query_exists (possible_path, cancellable))
+    g_clear_object (&possible_path);
+
+  ret = TRUE;
+  ot_transfer_out_value (out_path, &possible_path);
+  /*  out: */
+  return ret;
+}
+
+static gboolean
+update_grub (const char         *release,
+             GCancellable       *cancellable,
+             GError            **error)
+{
+  gboolean ret = FALSE;
+  ot_lobj GFile *grub_path = g_file_new_for_path ("/boot/grub/grub.conf");
+
+  if (g_file_query_exists (grub_path, cancellable))
+    {
+      gboolean have_grub_entry;
+      if (!grep_literal (grub_path, "OSTree", &have_grub_entry,
+                         cancellable, error))
+        goto out;
+
+      if (!have_grub_entry)
+        {
+          ot_lptrarray GPtrArray *grubby_args = NULL;
+          ot_lfree char *add_kernel_arg = NULL;
+          ot_lfree char *initramfs_arg = NULL;
+          ot_lobj GFile *kernel_path = NULL;
+
+          if (!get_kernel_path_from_release (release, &kernel_path, cancellable, error))
+            goto out;
+
+          if (kernel_path == NULL)
+            {
+              g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                           "Couldn't find kernel for release %s", release);
+              goto out;
+            }
+
+          grubby_args = g_ptr_array_new ();
+          add_kernel_arg = g_strconcat ("--add-kernel=", ot_gfile_get_path_cached (kernel_path), NULL);
+          initramfs_arg = g_strconcat ("--initrd=", "/boot/initramfs-ostree-", release, ".img", NULL);
+          ot_ptrarray_add_many (grubby_args, "grubby", "--grub", add_kernel_arg, initramfs_arg,
+                                "--copy-default", "--title=OSTree", NULL);
+          g_ptr_array_add (grubby_args, NULL);
+
+          g_print ("Adding OSTree grub entry...\n");
+          if (!ot_spawn_sync_checked (NULL, (char**)grubby_args->pdata, NULL, G_SPAWN_SEARCH_PATH,
+                                      NULL, NULL, NULL, NULL, error))
+            goto out;
+        } 
+      else
+        g_print ("Already have OSTree entry in grub config\n");
+    }
+  else
+    {
+      g_print ("/boot/grub/grub.conf not found, assuming you have GRUB 2\n");
+    }
+  
+  ret = TRUE;
+ out:
+  return ret;
+}
+
+gboolean
+ot_admin_builtin_update_kernel (int argc, char **argv, GError **error)
+{
+  GOptionContext *context;
+  OtAdminUpdateKernel self_data;
+  OtAdminUpdateKernel *self = &self_data;
+  gboolean ret = FALSE;
+  const char *deploy_target = NULL;
+  struct utsname utsname;
+  const char *release;
+  __attribute__((unused)) GCancellable *cancellable = NULL;
+
+  if (!opt_ostree_dir)
+    opt_ostree_dir = "/ostree";
+
+  memset (self, 0, sizeof (*self));
+
+  context = g_option_context_new ("[OSTREE_REVISION [KERNEL_RELEASE]] - Update kernel and regenerate initial ramfs");
+  g_option_context_add_main_entries (context, options, NULL);
+
+  if (!g_option_context_parse (context, &argc, &argv, error))
+    goto out;
+
+  if (argc > 1)
+    deploy_target = argv[1];
+  else
+    deploy_target = "current";
+
+  (void) uname (&utsname);
+  
+  if (strcmp (utsname.sysname, "Linux") != 0)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Unsupported machine %s", utsname.sysname);
+      goto out;
+    }
+  
+  release = utsname.release;
+  if (argc > 2)
+    release = argv[2];
+  
+  if (!copy_modules (release, cancellable, error))
+    goto out;
+  
+  if (!update_initramfs (release, deploy_target, cancellable, error))
+    goto out;
+  
+  if (!update_grub (release, cancellable, error))
+    goto out;
+
+  ret = TRUE;
+ out:
+  if (context)
+    g_option_context_free (context);
+  return ret;
+}
diff --git a/src/ostadmin/ot-admin-builtins.h b/src/ostadmin/ot-admin-builtins.h
index 44c2209..59d220b 100644
--- a/src/ostadmin/ot-admin-builtins.h
+++ b/src/ostadmin/ot-admin-builtins.h
@@ -29,6 +29,7 @@ G_BEGIN_DECLS
 
 gboolean ot_admin_builtin_init (int argc, char **argv, GError **error);
 gboolean ot_admin_builtin_deploy (int argc, char **argv, GError **error);
+gboolean ot_admin_builtin_update_kernel (int argc, char **argv, GError **error);
 
 G_END_DECLS