Libguestfs - Jun 2013 - Re: [PATCH] Mask some package names if appliance is build for SUSE

On Tue, Jun 11, Richard W.M. Jones wrote:
> But supermin is supposed to ignore packages that don't exist in the
> distro.  This is a bug in supermin or the zypp plugin for supermin.
It looks like zypper has no "ignore unknown packages/provides" flag. 
zypper .. install $pkg is called with an unknown package then zypper
will just abort because it expects valid input.

Maybe there should be some code which iterates over "names" and lets
zypper check for every single pkg and drop the ones which it can not
resolve. Later the smaller "names" list can be passed to zypper.

Are other plugins more forgiving in this?

Olaf

On Tue, Jun 11, Olaf Hering wrote:
> On Tue, Jun 11, Richard W.M. Jones wrote:
> 
> > But supermin is supposed to ignore packages that don't exist in
the
> > distro.  This is a bug in supermin or the zypp plugin for supermin.
Related to this, zypper --xml gives the chance to parse the output. But
doing it all in the shell is cumbersome. Right now there is no output if
something fails.

Whats the best way to do "xml sel -t -m
'stream/install-summary/to-install/solvable[@type='\''package'\'']'
-c
'string(@name)' -n" in ocaml itself? So zypper can write to a
tmpfile
and the .ml file can parse the xml output and process it as needed.

There is no obvious way to extract the "pkg not found" other than:
<message type="error">No provider of &apos;gdisk&apos;
found.</message>


Olaf

On Tue, Jun 11, 2013 at 04:07:17PM +0200, Olaf Hering
wrote:
> On Tue, Jun 11, Richard W.M. Jones wrote:
> 
> > But supermin is supposed to ignore packages that don't exist in
the
> > distro.  This is a bug in supermin or the zypp plugin for supermin.
> 
> It looks like zypper has no "ignore unknown packages/provides"
flag.
> zypper .. install $pkg is called with an unknown package then zypper
> will just abort because it expects valid input.
> 
> Maybe there should be some code which iterates over "names" and
lets
> zypper check for every single pkg and drop the ones which it can not
> resolve. Later the smaller "names" list can be passed to zypper.
> 
> Are other plugins more forgiving in this?
Yes.  For example, the yum/RPM plugin does effectively this:

  #!/usr/bin/python
  
  import yum
  import yum.misc
  import sys
  
  yb = yum.YumBase ()
  yb.setCacheDir ()
  
  patterns = ["bash", "notarealpackage"]
  pkgs = yb.pkgSack.returnPackages (patterns=patterns, repoid=0)
  for pkg in pkgs:
      print pkg

... which prints (after ages, for yum is very slow):

  bash-4.2.39-3.fc18.x86_64
  bash-4.2.45-1.fc18.x86_64

This is a feature of supermin, because it lets you have package lists
that don't need to be heavily conditionalized based on the precise
version of a distro, especially when packages are often being renamed
(like util-linux -> util-linux-ng and back again).

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
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http://people.redhat.com/~rjones/virt-top

On Tue, Jun 11, 2013 at 04:24:38PM +0200, Olaf Hering
wrote:
> On Tue, Jun 11, Olaf Hering wrote:
> 
> > On Tue, Jun 11, Richard W.M. Jones wrote:
> > 
> > > But supermin is supposed to ignore packages that don't exist
in the
> > > distro.  This is a bug in supermin or the zypp plugin for
supermin.
> 
> Related to this, zypper --xml gives the chance to parse the output. But
> doing it all in the shell is cumbersome. Right now there is no output if
> something fails.
> 
> Whats the best way to do "xml sel -t -m
>
'stream/install-summary/to-install/solvable[@type='\''package'\'']'
-c
> 'string(@name)' -n" in ocaml itself?
Unfortunately there's no best (or even good) way.  Two ways are:

 - Use an external OCaml library.  Ones I would recommend are:
   XML Light (very simple), xmlm (not used it but active upstream), or
   PXP (very comprehensive but also very masochistic).

 - Run the external bash command above and try parsing the output
   using regexps or something.  Has the possible advantage of not needing
   any extra OCaml deps.

Does zypper have a C API?  Binding C APIs from OCaml is easy (or
at least much easier than dealing with XML).
> So zypper can write to a tmpfile
> and the .ml file can parse the xml output and process it as needed.
> 
> There is no obvious way to extract the "pkg not found" other
than:
> <message type="error">No provider of
&apos;gdisk&apos; found.</message>
Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org