Setup the environment - Run VM in qemu

If you followed the previous two blog posts now you should have a rootfiles system, a kernel image and a compiled ceph to run on your host.

Now that we have everything that we need we should get to work in running the VM, the ceph filesystem and mount the filesystem into the guest VM.

The first step is to run the virtual machine using qemu. I have created a small script that just creates and configures a network bridge, a tap connected to it and to the VM and starts the virtual machine.

For this to happen smoothly you should install some packages:
	* bridge-utils  (in order to create a bridge)
	* isc-dhcp-server (to start a dhcp server on the bridge
	  interface)

In order to configure the dhcp server you should add the following entry at the end of /etc/dhcp/dhcpd.conf file:

    subnet 192.168.2.0 netmask 255.255.255.0 {
		range dynamic-bootp 192.168.2.5 192.168.2.150;
		option broadcast-address 192.168.2.255;
		option routers 192.168.2.4 ;
	}

The folder structure in which I copied the rootfs and the kernel is
the following:

drwxrwxr-x  5 ioana 1000 4096 Jan 20 15:36 ./
drwxr-xr-x 25 ioana 1000 4096 Jan 20 13:17 ../
drwxrwxr-x 24 ioana 1000 4096 Dec 30 02:09 ceph/
drwxrwxr-x 26 ioana 1000 4096 Jan 20 16:28 ceph-client/
drwxr-xr-x  3 root  root 4096 Jan 20 16:45 testing/

drwxr-xr-x 3 root  root  4096 Jan 20 16:45 ./
drwxrwxr-x 5 ioana  1000 4096 Jan 20 15:36 ../
drwxr-xr-x 2 root  root  4096 Jan 20 16:08 boot_files/
-rwxrwxr-x 1 ioana users  614 Jan 20 16:46 launch.sh*

root@yoga:/home/ioana/work/testing# ll boot_files/
drwxr-xr-x 2 root root       4096 Jan 20 16:08 ./
drwxr-xr-x 3 root root       4096 Jan 20 16:45 ../
-rw-r--r-- 1 root root    6307248 Jan 20 16:28 bzImage
-rw-r--r-- 1 root root 1073741824 Jan 20 16:47 rootfs.img


The script that you need to use in order to launch the qemu VM is:

#! /bin/sh

brctl addbr br0
ip addr add 192.168.5.4/24 broadcast 192.168.5.255 dev br0
ip link set br0 up

ip tuntap add dev tap0 mode tap
ip link set tap0 up promisc on

brctl addif br0 tap0

qemu-system-x86_64  -M pc -m 1024 -no-reboot -kernel \
boot_files/bzImage  -append "highres=off \
root=/dev/sda rootfstype=ext3" \
-hda  boot_files/rootfs.img \
-net nic,macaddr="52:54:be:36:42:a9" -net tap,ifname=tap0,script=no,downscript=no

ip link set br0 down
brctl delbr br0

ip link set tap0 down
ip link delete tap0