User:Ncopa/migrate-vserver-to-lxc
Some notes on how to migrate an Alpine Linux vserver to an lxcontainer.
Its fairly straightforward. Basically, the only thing that differs is:
- /etc/inittab
- /etc/network/interfaces
On vserver the host sets up the network, on LXC the container needs to do it itself.
Migration steps
Here follows some step by step. build-edge-x86 is used as example.
Create container
Create the new container on the LXC host
lxc-create -n build-edge-x86 -t alpine -- --release edge --arch x86
Backup inittab
Make a copy of the inittab to a location outside the container rootfs.
cp /var/lib/lxc/build-edge-x86/rootfs/etc/inittab /var/lib/lxc/build-edge-x86/
Copy data
Use rsync to mirror the vserver. We do this before we shut down the vserver guest to keep downtime as low as possible. In this example we rsync from the vserver host:
rsync --partial --delete --numeric-ids -rva /vservers/build-edge/* bld1.alpinelinux.org:/var/lib/lxc/build-ege-x86/rootfs/
Configure networking
While data is copying we can use the time to configure the network. Edit /var/lib/lxc/build-edge-x86/config and set up the network devices. In this example we do:
Contents of /var/lib/lxc/build-edge-x86/config
We can also create a interfaces file that we will copy into the container after old vserver is shutdown.
Contents of /var/lib/lxc/build-edge-x86/interfaces
Shut down old vserver
After data is copied we shut down the old vserver. This is on old Vserver host.
vserver build-edge stop
Mirror data again
We mirror the changes on the powered off vserver once again so we get the changes that happened after first data copy started. This is done from vserver host here.
rsync --partial --delete --numeric-ids -rva /vservers/build-edge/* bld1.alpinelinux.org:/var/lib/lxc/build-ege-x86/rootfs/
We rename the vserver so its not started/copied by mistake.
mv /vservers/build-edge /vserver/build-edge.old
We unmark the auto-start.
rm /etc/vservers/build-edge/apps/init/mark
Prepare lxcontainer for startup
Before we start up the container we copy the inittab. This is on new LXC host.
cp /var/lib/lxc/build-edge-x86/inittab /var/lib/lxc/build-edge-x86/rootfs/etc/
...and we copy the interfaces file too.
cp /var/lib/lxc/build-edge-x86/interfaces /var/lib/lxc/build-edge-x86/rootfs/etc/networking/
We make sure networking is started at bootup.
ln -s /etc/init.d/networking /var/lib/lxc/build-edge-x86/rootfs/etc/runlevels/default/networking
TODO: send GARP to tell switch of new ip.