All of this needs a rewrite/redesign, and that will be coming (details
below), but for now
You can start 'non-ephemeral ephemeral' containers using
lxc-start-ephemeral -o oldname -n newname --keep-data
When you shut that down, the container stick around and can be
restarted. Now lxc-clone will recognize such a container by the
presence of the delta0/ which contains the read-write overlayfs
layer. This means you can do incremental development of containers,
i.e.
lxc-create -t ubuntu -n r1
lxc-start-ephemeral --keep-data -o r1 -n r1-2
# make some changes, poweroff
lxc-clone -o r1-2 -n r1-3
# make some changes...
lxc-clone -o r1-3 -n r1-4
# etc...
Now, as for design changes... from a higher level
1. lxc-clone should be re-written in c and exported through the
api.
2. lxc-clone should support overlayfs and aufs
3. lxc-start-ephemeral should become a thin layer which clones a
container, starts and stops and destroys it.
at a lower level,
1. the api should support container->setup_mounts
2. lxc-clone should be written as a set of backend classes which
can copy mounts to each other. So when you load a container
which is lvm-backed, it creates a lvm backend class. That
class instance can be converted into a loopback or qemu-nbd
or directory backed class. A directory-backed class can be
converted into a overlayfs or aufs backed class, which (a)
uses the dirctory-backed class as the read-only base, and (b)
pins the base container (so it can't be deleted until all
snapshots are deleted).
Signed-off-by: Serge Hallyn <[email protected]>
---
src/lxc/lxc-clone.in | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/src/lxc/lxc-clone.in b/src/lxc/lxc-clone.in
index 291db30..4c8acb4 100755
--- a/src/lxc/lxc-clone.in
+++ b/src/lxc/lxc-clone.in
@@ -251,6 +251,23 @@ elif which btrfs >/dev/null 2>&1 && btrfs subvolume list
$oldroot >/dev/null 2>&
# if oldroot is a btrfs subvolume, assume they want a snapshot
btrfs subvolume snapshot "$oldroot" "$rootfs" 2>&1 || { echo "$(basename
$0): btrfs snapshot failed" >&2; false; }
echo "lxc.rootfs = $rootfs" >> "$lxc_path/$lxc_new/config"
+elif [ -d $lxc_path/$lxc_orig/delta0 ]; then # this is a quasi-ephemeral
container
+ if [ $container_running = "True" ]; then
+ echo "$(basename $0): container $lxc_orig is running." >&2
+ cleanup
+ fi
+ rsync -Hax $lxc_path/$lxc_orig/delta0 $lxc_path/$lxc_new/
+ touch $lxc_path/$lxc_new/configured
+ cp -f $lxc_path/$lxc_orig/pre-mount $lxc_path/$lxc_new/
+ sed -i "s@$lxc_path/$lxc_orig@$lxc_path/$lxc_new@g"
$lxc_path/$lxc_new/config
+ sed -i "s@$lxc_path/$lxc_orig@$lxc_path/$lxc_new@g"
$lxc_path/$lxc_new/pre-mount
+ sed -i "s@LXC_NAME=\"$lxc_orig@LXC_NAME=\"$lxc_new@"
$lxc_path/$lxc_new/pre-mount
+ # lxc-start-ephemeral will have updated /etc/hostname and such under the
+ # delta0, so just mounting the delta should suffice.
+ mkdir -p $rootfs
+ mount --bind $lxc_path/$lxc_new/delta0 $rootfs
+ mounted=1
+ echo "lxc.rootfs = $rootfs" >> "$lxc_path/$lxc_new/config"
else
if [ $snapshot = "yes" ]; then
echo "$(basename $0): cannot snapshot a directory" >&2
--
1.8.1.2
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