1:48 p.m.
Inspired by something Glauber asked me about today, I made a very
simple pair of patches which add a 'virt-rescue' command to
libguestfs. This uses the appliance as a "rescue appliance", so
people can boot into a disk image and repair it in an unstructured,
interactive way. (Specifically, Glauber's question was how to run
fsck interactively - with this patch you could do that).
Example session:
$ virt-rescue --ro /dev/vg_trick/F11x64
Welcome to virt-rescue, the libguestfs rescue shell.
Note: The contents of / are the rescue appliance.
You have to mount the guest's partitions under /sysroot
before you will be able to examine them.
bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell
<rescue> mount /dev/vg_f11x64/lv_root /sysroot
EXT4-fs
(dm-0): barriers enabled
kjournald2 starting: pid 269, dev dm-0:8, commit interval 5 seconds
EXT4-fs (dm-0): internal journal on dm-0:8
EXT4-fs (dm-0): delayed allocation enabled
EXT4-fs: file extents enabled
EXT4-fs: mballoc enabled
EXT4-fs (dm-0): mounted filesystem with ordered data mode
<rescue> ls /sysroot/
bin dev home lib64 media
opt root selinux sys usr
boot etc lib lost+found mnt proc sbin srv tmp var
<rescue> exit
I'd really like to know how to get rid of that bash error message.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 75 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora
1:55 p.m.
There are actually going to be 3 patches in this series.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://et.redhat.com/~rjones/libguestfs/
See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html
2 p.m.
New subject: [PATCH 1/3] Tidy up appliance rescue code.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 75 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora
5:12 a.m.
New subject: [PATCH 1/3] Tidy up appliance rescue code.
Richard W.M. Jones wrote:
Subject: [PATCH 1/3] Tidy up appliance rescue code.
The appliance shouldn't run the daemon after we leave the
rescue shell. It should just exit instead.
---
appliance/init | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/appliance/init b/appliance/init
index fe135b4..8b97590 100755
--- a/appliance/init
+++ b/appliance/init
@@ -61,7 +61,11 @@ lsmod
# Improve virtio-blk performance (RHBZ#509383).
for f in /sys/block/vd*/queue/rotational; do echo 1 > $f; done
-if grep -sq guestfs_rescue=1 /proc/cmdline; then
- bash -i
+if ! grep -sq guestfs_rescue=1 /proc/cmdline; then
+ exec guestfsd -f
fi
-exec guestfsd -f
+
+TERM=linux ;# XXX library should pass this from library's environment
+PS1='><rescue> '
+export TERM PS1
+exec bash -i
Looks right.
ACK
2:01 p.m.
New subject: [PATCH 2/3] Add direct appliance mode flag and implementation.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
7:44 a.m.
New subject: [PATCH 2/3] Add direct appliance mode flag and implementation.
Richard W.M. Jones wrote:
Subject: [PATCH 2/3] Add direct appliance mode flag and
implementation.
When the g->direct flag is set, the appliance stdin/stdout
are not connected to the library. Instead they inherit the
stdin/stdout of the caller.
THis looks fine. ACK
...
diff --git a/src/guestfs.c b/src/guestfs.c
index 6eafcf5..03089ea 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -119,6 +119,7 @@ struct guestfs_h
int verbose;
int trace;
int autosync;
+ int direct;
char *path; /* Path to kernel, initrd. */
char *qemu; /* Qemu binary. */
@@ -651,6 +652,19 @@ guestfs__get_trace (guestfs_h *g)
return g->trace;
}
+int
+guestfs__set_direct (guestfs_h *g, int d)
+{
+ g->direct = !!d;
+ return 0;
+}
+
+int
+guestfs__get_direct (guestfs_h *g)
+{
+ return g->direct;
+}
Probably of only marginal benefit (who has const guestfs_h* pointers?),
but at least from its definition, you can see that this parameter
can be "const".
2:01 p.m.
New subject: [PATCH 3/3] Add 'virt-rescue' command.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
5:36 a.m.
New subject: [PATCH 3/3 VERSION 2] Add 'virt-rescue' command.
Slightly updated patch, which just changes the documentation.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.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/
5:36 a.m.
New subject: [PATCH 3/3] Add 'virt-rescue' command.
Richard W.M. Jones wrote:
...
Subject: [PATCH 3/3] Add 'virt-rescue' command.
This command runs a "rescue appliance" against a virtual machine
or disk image. This is useful for making ad-hoc interactive
...
diff --git a/rescue/Makefile.am b/rescue/Makefile.am
...
+if HAVE_RESCUE
+
+man_MANS = virt-rescue.1
I have a vague memory that recent automake generates
better rules if you spell the above like this:
dist_man1_MANS = virt-rescue.1
+noinst_DATA = @top_builddir(a)/html/virt-rescue.1.html
IMHO, it's better to avoid automake's obsolescent @VAR@ notation.
Instead, use $(VAR). There's even a syntax-check rule for this,
but it's currently disabled.
+virt-rescue.1: virt-rescue.pl
+ $(POD2MAN) \
+ --section 1 \
+ -c "Virtualization Support" \
+ --release "$(PACKAGE_NAME)-$(PACKAGE_VERSION)" \
+ $< > $@
Don't redirect directly to $@, in case the command fails
without removing the incomplete result. This idiom ensures
that it is updated atomically:
$< > $@-t && mv $@-t $@
+@top_builddir(a)/html/virt-rescue.1.html: virt-rescue.pl
+ mkdir -p @top_builddir@/html
+ cd @top_builddir@ && pod2html \
+ --css 'pod.css' \
+ --title 'virt-rescue, run a rescue shell on a virtual machine' \
+ --htmldir html \
+ --outfile html/virt-rescue.1.html \
+ rescue/$<
+
+install-data-hook:
+ mkdir -p $(DESTDIR)$(bindir)
+ install -m 0755 virt-rescue.pl $(DESTDIR)$(bindir)/virt-rescue
+
+endif
diff --git a/rescue/run-rescue-locally b/rescue/run-rescue-locally
...
+my $path = $0;
+
+# Follow symlinks until we get to the real file
+while(-l $path) {
+ my $link = readlink($path);
You'll want to handle the case in which readlink fails
and returns "undef".
+ if(File::Spec->file_name_is_absolute($link)) {
+ $path = $link;
+ } else {
+ $path = File::Spec->catfile(dirname($path), $link);
+ }
6:10 a.m.
New subject: [PATCH 3/3] Add 'virt-rescue' command.
On Wed, Sep 23, 2009 at 12:36:34PM +0200, Jim Meyering wrote:
Richard W.M. Jones wrote:
> +man_MANS = virt-rescue.1
I have a vague memory that recent automake generates
better rules if you spell the above like this:
dist_man1_MANS = virt-rescue.1
I'm not sure if that would work with the older automakes.
The other three things, I will submit as separate patches in a moment,
since the same problems affect four other directories too.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://et.redhat.com/~rjones/libguestfs/
See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html
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