Libguestfs - Aug 2012 - libguestfs! help!

On Sun, Aug 26, 2012 at 09:52:23PM -0400, tao zhou
wrote:
> hello everyone!
>
> first i use libguestfs API to upload a file into my linux VM , and
> then i want to execute some command(for example : tar xzvf XXX?
> chkconfig --add XXX) to config my application by java libguestfs
> API?what should i do? could you show me an example in java?
> Thanks!
Attached is a simple example in Java.

However to run the command it may be better to run the command using a
"firstboot" script.  See:

  http://libguestfs.org/guestfs.3.html#running-commands
  http://libguestfs.org/virt-sysprep.1.html#firstboot-

(Note that the ability to use firstboot scripts was only added very
recently to virt-sysprep).

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
programs, test, and build Windows installers. Over 70 libraries supprt'd
http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw
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// Example showing how to upload file(s) and run commands in a VM.
// javac Example.java -classpath /usr/share/java/libguestfs-*.jar

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.redhat.et.libguestfs.*;

public class Example
{
    static final Comparator<String> COMPARE_KEYS_LEN         new
Comparator<String>() {
        public int compare (String k1, String k2) {
            return k1.length() - k2.length();
        }
    };

    public static void main (String[] argv)
    {
        try {
            if (argv.length != 2)
                throw new Error ("usage: Example disk.img
content.tar.gz");

            String disk = argv[0];
            String content_tgz = argv[1];

            GuestFS g = new GuestFS ();

            g.add_drive_opts (disk, null);

            // Run the libguestfs back-end.
            g.launch ();

            // Ask libguestfs to inspect for operating systems.
            String roots[] = g.inspect_os ();
            if (roots.length == 0)
                throw new Error ("no operating systems found");
            if (roots.length > 1)
                throw new Error ("multi-boot VM is not supported");

            String root = roots[0];

            // Mount up the disks, like guestfish -i.
            //
            // Sort keys by length, shortest first, so that we end up
            // mounting the filesystems in the correct order.
            Map<String,String> mps = g.inspect_get_mountpoints (root);
            List<String> mps_keys = new ArrayList (mps.keySet ());
            Collections.sort (mps_keys, COMPARE_KEYS_LEN);

            for (String mp : mps_keys) {
                String dev = mps.get (mp);
                try {
                    g.mount (dev, mp);
                }
                catch (Exception exn) {
                    System.err.println (exn + " (ignored)");
                }
            }

            // Upload content.
            g.tgz_in (content_tgz, "/");

            // Run a command.
            String cmd = "chkconfig --add myservice";
            g.sh (cmd);

            // Unmount everything.
            g.umount_all ();
        }
        catch (Exception exn) {
            System.err.println (exn);
            System.exit (1);
        }
    }
}

I realized that this code is missing the call to shutdown the disk and
detect write errors.  (Sorry about that -- the code was adapted from a
read-only example where this is not necessary).
>             // Unmount everything.
>             g.umount_all ();
After these two lines, add:

     g.shutdown ();
     g.close ();

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v

i try it in my environment?it allways throws the exception :
com.redhat.et.libguestfs.LibGuestFSException: sh: /bin/sh: Exec format error
then i try the following programs, "Exec format error" still happens:
String cmd1 = "chkconfig --add tomcat";
g.sh(cmd1);
String cmd2 = "/sbin/chkconfig --add tomcat";
g.sh(cmd2);
String[] cmd = new String[] {"/sbin/chkconfig", "--list"};
g.command(cmd);
but i can execute the command in system, could show me the reason, Thanks!




??

From: Richard W.M. Jones
Date: 2012-08-28 00:39
To: libguestfs at redhat.com
CC: tao.zhou at neusoft.com
Subject: Re: libguestfs! help!
On Sun, Aug 26, 2012 at 09:52:23PM -0400, tao zhou
wrote:
> hello everyone!
>
> first i use libguestfs API to upload a file into my linux VM , and
> then i want to execute some command(for example : tar xzvf XXX?
> chkconfig --add XXX) to config my application by java libguestfs
> API?what should i do? could you show me an example in java?
> Thanks!
Attached is a simple example in Java.

However to run the command it may be better to run the command using a
"firstboot" script.  See:

  http://libguestfs.org/guestfs.3.html#running-commands
  http://libguestfs.org/virt-sysprep.1.html#firstboot-

(Note that the ability to use firstboot scripts was only added very
recently to virt-sysprep).

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
programs, test, and build Windows installers. Over 70 libraries supprt'd
http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw
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On Wed, Aug 29, 2012 at 11:34:51AM +0800, ?? wrote:
> i try it in my environment?it allways throws the exception :
> com.redhat.et.libguestfs.LibGuestFSException: sh: /bin/sh: Exec format
error
> then i try the following programs, "Exec format error" still
happens:
> String cmd1 = "chkconfig --add tomcat";
> g.sh(cmd1);
> String cmd2 = "/sbin/chkconfig --add tomcat";
> g.sh(cmd2);
> String[] cmd = new String[] {"/sbin/chkconfig",
"--list"};
> g.command(cmd);
> but i can execute the command in system, could show me the reason, Thanks!
Well it's something to do with the guest being either a much older or
much newer version of Linux than the host, or perhaps it's a different
architecture (32 vs 64 bits?), or not even Linux at all.

The way to solve this is to use a firstboot script:
> From: Richard W.M. Jones
> Date: 2012-08-28 00:39
> To: libguestfs at redhat.com
[...]
> However to run the command it may be better to run the command using a
> "firstboot" script.  See:
> 
>   http://libguestfs.org/guestfs.3.html#running-commands
>   http://libguestfs.org/virt-sysprep.1.html#firstboot-
> 
> (Note that the ability to use firstboot scripts was only added very
> recently to virt-sysprep).
Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/