Re: [PATCH 2/2] wic: Add --embed-rootfs argument

[Paul Barker <pbarker@konsulko.com>]

On Wed, 4 Mar 2020 10:56:20 +0100
Ricardo Ribalda Delgado <ricardo@ribalda.com> wrote:

> Hi Paul
> 
> Thanks for your reply
> 
> On Wed, Mar 4, 2020 at 10:43 AM Paul Barker <pbarker@konsulko.com> wrote:
> >
> > On Wed,  4 Mar 2020 09:34:38 +0100
> > Ricardo Ribalda Delgado <ricardo@ribalda.com> wrote:
> >  
> > > This option adds the content of a rootfs on a specific location on the
> > > rootfs.
> > >
> > > It is very useful for making a partition that contains the rootfs for a
> > > host and a target Eg:
> > >
> > > / -> Roofs for the host
> > > /export/ -> Rootfs for the target (which will netboot)
> > >
> > > Although today we support making a partition for "/export" this might
> > > not be compatible with some upgrade systems, or we might be limited by
> > > the number of partitions.
> > >
> > > With this patch we can use something like:
> > >
> > > part / --source rootfs --embed-rootfs=target-image:/export  
> >
> > I considered using a syntax like this for --include-path but I chose not to
> > as it's not easy to choose a separator. ':' is a valid character in a
> > directory name.  
> 
> I think we have to live with not being able to copy files to a
> directory with a colon :(

I wouldn't like to place a limitation like that on users and I'd like to
avoid the proliferation of similar arguments here.

How about modifying '--include-path' to take two arguments, a source path and
a destination prefix? The python argument parser should be able to handle
this and you can build a list of tuples (source_path, dest_prefix) when
parsing the arguments.

The '--include-path' argument hasn't been part of a Yocto release yet it's
just on the master branch so I think if we're going to fix it with a breaking
change, now is definitely the time.

> 
> >
> > My approach is to handle this in two steps:
> >
> > 1) Add a new task before do_image_wic which creates an 'embedded-rootfs'
> >   directory and copies 'target-image' to 'embedded-rootfs/export'.
> >
> > 2) Use '--include-path=embedded-rootfs' in the wks file.
> >  
> 
> The biggest problem with that approach is permissions. We need files
> with UID 0, siticky bits, etc. We lose the pseudo database if we
> simply copy to a folder.
> 
> Also, if we have a complex system with multiple partitions I prefer to
> handle all in a single .wks file instead of a script + wks file
> 
> > >
> > > on the .wks file.
> > >
> > > Signed-off-by: Ricardo Ribalda Delgado <ricardo@ribalda.com>
> > > ---
> > >  scripts/lib/wic/help.py                  |  7 +++++++
> > >  scripts/lib/wic/ksparser.py              |  1 +
> > >  scripts/lib/wic/partition.py             |  1 +
> > >  scripts/lib/wic/plugins/source/rootfs.py | 20 +++++++++++++++++++-
> > >  4 files changed, 28 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/scripts/lib/wic/help.py b/scripts/lib/wic/help.py
> > > index 4d342fcf05..67a33e6a65 100644
> > > --- a/scripts/lib/wic/help.py
> > > +++ b/scripts/lib/wic/help.py
> > > @@ -979,6 +979,13 @@ DESCRIPTION
> > >                           copies. This option only has an effect with the rootfs
> > >                           source plugin.
> > >
> > > +         --embed-rootfs: This option is specific to wic. It embeds a rootfs into
> > > +                         the given path to the resulting image. The option
> > > +                         contains two fields, the roofs and the path, separated
> > > +                         by a colon. The rootfs follows the same logic as the
> > > +                         rootfs-dir argument. This option only has an effect
> > > +                         with the rootfs source plugin.
> > > +
> > >           --extra-space: This option is specific to wic. It adds extra
> > >                          space after the space filled by the content
> > >                          of the partition. The final size can go
> > > diff --git a/scripts/lib/wic/ksparser.py b/scripts/lib/wic/ksparser.py
> > > index 650b976223..d422e2a6bb 100644
> > > --- a/scripts/lib/wic/ksparser.py
> > > +++ b/scripts/lib/wic/ksparser.py
> > > @@ -138,6 +138,7 @@ class KickStart():
> > >          part.add_argument('--align', type=int)
> > >          part.add_argument('--exclude-path', nargs='+')
> > >          part.add_argument('--include-path', nargs='+')
> > > +        part.add_argument('--embed-rootfs', nargs='+')
> > >          part.add_argument("--extra-space", type=sizetype)
> > >          part.add_argument('--fsoptions', dest='fsopts')
> > >          part.add_argument('--fstype', default='vfat',
> > > diff --git a/scripts/lib/wic/partition.py b/scripts/lib/wic/partition.py
> > > index 2d95f78439..13857df82f 100644
> > > --- a/scripts/lib/wic/partition.py
> > > +++ b/scripts/lib/wic/partition.py
> > > @@ -31,6 +31,7 @@ class Partition():
> > >          self.extra_space = args.extra_space
> > >          self.exclude_path = args.exclude_path
> > >          self.include_path = args.include_path
> > > +        self.embed_rootfs = args.embed_rootfs
> > >          self.fsopts = args.fsopts
> > >          self.fstype = args.fstype
> > >          self.label = args.label
> > > diff --git a/scripts/lib/wic/plugins/source/rootfs.py b/scripts/lib/wic/plugins/source/rootfs.py
> > > index 40419a64b3..16359601dc 100644
> > > --- a/scripts/lib/wic/plugins/source/rootfs.py
> > > +++ b/scripts/lib/wic/plugins/source/rootfs.py
> > > @@ -80,7 +80,7 @@ class RootfsPlugin(SourcePlugin):
> > >
> > >          new_rootfs = None
> > >          # Handle excluded paths.
> > > -        if part.exclude_path or part.include_path:
> > > +        if part.exclude_path or part.include_path or part.embed_rootfs:
> > >              # We need a new rootfs directory we can delete files from. Copy to
> > >              # workdir.
> > >              new_rootfs = os.path.realpath(os.path.join(cr_workdir, "rootfs%d" % part.lineno))
> > > @@ -100,6 +100,24 @@ class RootfsPlugin(SourcePlugin):
> > >              for path in part.include_path or []:
> > >                  copyhardlinktree(path, new_rootfs)
> > >
> > > +            for embed in part.embed_rootfs or []:
> > > +                [embed_rootfs, path] = embed.split(":")
> > > +                #we need to remove the initial / for os.path.join to work
> > > +                if os.path.isabs(path):
> > > +                    path = path[1:]
> > > +                if embed_rootfs in krootfs_dir:
> > > +                    embed_rootfs = krootfs_dir[embed_rootfs]
> > > +                embed_rootfs = cls.__get_rootfs_dir(embed_rootfs)
> > > +                tar_file = os.path.realpath(os.path.join(cr_workdir, "aux.tar"))
> > > +                tar_cmd = "%s tar cpf %s -C %s ." % (cls.__get_pseudo(native_sysroot,
> > > +                                                     embed_rootfs), tar_file, embed_rootfs)
> > > +                exec_native_cmd(tar_cmd, native_sysroot)
> > > +                untar_cmd = "%s tar xf %s -C %s ." % (cls.__get_pseudo(native_sysroot, new_rootfs),
> > > +                                                      tar_file, os.path.join(new_rootfs, path))
> > > +                exec_native_cmd(untar_cmd, native_sysroot,
> > > +                                cls.__get_pseudo(native_sysroot, new_rootfs))
> > > +                os.remove(tar_file)
> > > +  
> >
> > Why are you using an intermediate tar file here?  
> 
> For the permissions :(

Your previous patch handled this using 'pseudo -B'. It would be good to be
consistent if possible - either use an intermediate tar file in all cases if
it's necessary or use 'pseudo -B' in all cases.

-- 
Paul Barker
Konsulko Group