Libguestfs - Sep 2016 - [PATCH v4] v2v: linux: correctly reconfigure the initrd on Debian

Using update-initramfs is the native way of updating initrd on Debian
based systems.

To add some modules to the image we can list them in file
/etc/initramfs-tools/modules.

Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
---
 v2v/convert_linux.ml | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/v2v/convert_linux.ml b/v2v/convert_linux.ml
index 08f4b2a..22a7919 100644
--- a/v2v/convert_linux.ml
+++ b/v2v/convert_linux.ml
@@ -478,6 +478,15 @@ let rec convert ~keep_serial_console (g : G.guestfs)
inspect source rcaps          ignore (g#command (Array.of_list args))
       in
 
+      let run_update_initramfs_command () +        let args +         
"/usr/sbin/update-initramfs"  ::
+            (if verbose () then [ "-v" ] else [])
+          @ [ "-c"; "-k"; mkinitrd_kv ]
+        in
+        ignore (g#command (Array.of_list args))
+      in
+
       if g#is_file ~followsymlinks:true "/sbin/dracut" then
         run_dracut_command "/sbin/dracut"
       else if g#is_file ~followsymlinks:true "/usr/bin/dracut" then
@@ -491,6 +500,30 @@ let rec convert ~keep_serial_console (g : G.guestfs)
inspect source rcaps                         "-k"; kernel.ki_vmlinuz
|]
         )
       )
+      else if family = `Debian_family then (
+        if not (g#is_file ~followsymlinks:true
"/usr/sbin/update-initramfs") then
+          error (f_"unable to rebuild initrd (%s) because update-initramfs
was not found in the guest")
+            initrd;
+
+        if List.length modules > 0 then (
+          (* The modules to add to initrd are defined in:
+          *     /etc/initramfs-tools/modules
+          * File format is same as modules(5).
+          *)
+          let file = "/etc/initramfs-tools/modules" in
+          let path = sprintf "/files%s" file in
+          g#aug_transform "modules" file;
+          g#aug_load ();
+          g#aug_set (sprintf "%s/#comment[last()+1]" path)
+            "The following modules were added by virt-v2v";
+          List.iter (
+            fun m -> g#aug_clear (sprintf "%s/%s" path m)
+          ) modules;
+          g#aug_save ();
+        );
+
+        run_update_initramfs_command ()
+      )
       else if g#is_file ~followsymlinks:true "/sbin/mkinitrd" then (
         let module_args = List.map (sprintf "--with=%s") modules in
         let args -- 
2.9.3

v4 changes: using Augeas to do the dirty job

On Friday, 16 September 2016 13:10:37 CEST Tomáš Golembiovský
wrote:
> Using update-initramfs is the native way of updating initrd on Debian
> based systems.
> 
> To add some modules to the image we can list them in file
> /etc/initramfs-tools/modules.
> 
> Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
> ---
>  v2v/convert_linux.ml | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/v2v/convert_linux.ml b/v2v/convert_linux.ml
> index 08f4b2a..22a7919 100644
> --- a/v2v/convert_linux.ml
> +++ b/v2v/convert_linux.ml
> @@ -478,6 +478,15 @@ let rec convert ~keep_serial_console (g : G.guestfs)
inspect source rcaps >          ignore (g#command (Array.of_list args))
>        in
>  
> +      let run_update_initramfs_command () > +        let args > +   
"/usr/sbin/update-initramfs"  ::
> +            (if verbose () then [ "-v" ] else [])
> +          @ [ "-c"; "-k"; mkinitrd_kv ]
> +        in
> +        ignore (g#command (Array.of_list args))
> +      in
> +
>        if g#is_file ~followsymlinks:true "/sbin/dracut" then
>          run_dracut_command "/sbin/dracut"
>        else if g#is_file ~followsymlinks:true "/usr/bin/dracut"
then
> @@ -491,6 +500,30 @@ let rec convert ~keep_serial_console (g : G.guestfs)
inspect source rcaps >                         "-k";
kernel.ki_vmlinuz |]
>          )
>        )
> +      else if family = `Debian_family then (
> +        if not (g#is_file ~followsymlinks:true
"/usr/sbin/update-initramfs") then
> +          error (f_"unable to rebuild initrd (%s) because
update-initramfs was not found in the guest")
> +            initrd;
> +
> +        if List.length modules > 0 then (
> +          (* The modules to add to initrd are defined in:
> +          *     /etc/initramfs-tools/modules
> +          * File format is same as modules(5).
> +          *)
> +          let file = "/etc/initramfs-tools/modules" in
> +          let path = sprintf "/files%s" file in
IMHO you can avoid this help variable, and just write "/files"
directly
in the two places below.
> +          g#aug_transform "modules" file;
> +          g#aug_load ();
Use Linux.augeas_init here -- it's roughly the same, but it logs Augeas
errors.
> +          g#aug_set (sprintf "%s/#comment[last()+1]" path)
> +            "The following modules were added by virt-v2v";
> +          List.iter (
> +            fun m -> g#aug_clear (sprintf "%s/%s" path m)
> +          ) modules;
You can use currying here:

  List.iter (g#aug_clear (sprintf "/files%s/%s") file) modules;

With the above files, LGTM.

Thanks,
-- 
Pino Toscano