qemu + vde on slackware 13.1

Ramurd · 09-04-2010, 03:22 PM

You should; As Eric said, it was my main reason to start using VDE as well: no root authority needed to start a VM with "true" networking support.

Btw; got a bit early home tonight, so started on the script; the crude 1st part of parsing the ini file is done now, more or less. It's very basic and won't start your VM yet; in fact it does nothing other than echo stuff, but it gives an idea of the direction I'm thinking of going... Share your ideas with me and it may grow to something quite funny :-)

Code:

#!/bin/ksh

# ksh is more or less required due to scoping of variables
# bash is picky and doesn't scope outside piped loops :-(

machine=${1}
inifile="check.ini"

parse_inifile()
{
	section_start=`cat ${inifile} | grep -v "^#" | grep -n "^\[${machine}\]$" | cut -d ':' -f 1`
	
	if [ -z "${section_start}" ]
	then
	        echo "Not found; valid sections are: "
	        cat ${inifile} | grep -v "^#" | grep -e "^\[.*\]$" | cut -d '[' -f 2 - | cut -d ']' -f 1
	        exit
	fi
	
	section_end=`cat ${inifile} | grep -v "^#" | grep -e "^$" -n | cut -d ':' -f 1 | while read num
	do
		if [ ${num} -gt ${section_start} ]
		then
			echo ${num}
		fi
	done | head -n 1`
	
	((diff=section_end - section_start))
	
	echo "Start: ${section_start}"
	echo "End  : ${section_end}"
	echo "Diff : ${diff}"
	cat ${inifile} | grep -v "^#" | tail -n +${section_start} | head -n ${diff} | while read option
	do
		echo "${#OPT[*]}: ${option}" 
		OPT[${#OPT[*]}]=${option}
	done 
}

parse_options()
{
	COUNT=0
	PARAMETERS=""

	while [ ${COUNT} -lt ${#OPT[*]} ]
	do
		((COUNT+=1)) # we can safely do this; as OPT[0] is the section header
		ARG=`echo ${OPT[${COUNT}]} | cut -d '=' -f 1` 
		VAL=`echo ${OPT[${COUNT}]} | cut -d '=' -f 2-`

		case ${ARG} in
			"")
				PARAMETERS=${PARAMETERS}
				;; # yes pretty silly, right?

			"machine")
				PARAMETERS="${PARAMETERS}-M ${VAL} "
				;;
			*)
				PARAMETERS="${PARAMETERS} -${ARG} ${VAL} "
				;;
		esac
	done
	echo ${PARAMETERS}
}

main()
{
	parse_inifile
	parse_options
}

main

The idea is to have an ini file that has these requirements:
- Each machine starts with [<machine name>]
- an empty line means the end of the machine definition
- comments are possible with an # at the very start of the line
- parameters to be passed to qemu are similar put as <parameter minus the leading ->=<value>
- other things can be put in the ini file, for which I have to write the support yet; e.g. qemu_binary=/usr/bin/qemu

Chuck56 · 09-04-2010, 04:20 PM

Quote:

Originally Posted by Ramurd

You should; As Eric said, it was my main reason to start using VDE as well: no root authority needed to start a VM with "true" networking support.

That is a valuable attribute of VDE but I currently use a slightly different approach. Any machine, desktop or server, that has qemu-kvm installed also has my bridge start up script run from rc.local. I run the bridge all the time on those machines. Does that make sense?

Granted I have to provision a separate tap interface for each guest but I rarely run more than 3 guests simultaneously so I setup 3 tap interfaces that are referenced in my consolidated guest config file. The config file is not an ini or xml but just a script that is called by other scripts and assigns values to variables and arrays.

I really like what you're doing with your script and look forward to future updates on your progress!

Slax-Dude · 09-04-2010, 07:21 PM

Quote:

Originally Posted by Chuck56

I currently use a slightly different approach. Any machine, desktop or server, that has qemu-kvm installed also has my bridge start up script run from rc.local. I run the bridge all the time on those machines. Does that make sense?

It makes perfect sense to me

Before I switched to libvirt, I used VDE + bridge, because I wanted my VMs to access all my physical machines as well as the internet, instead of being confined to their own network segment. It also makes things simpler, as I didn't need dnsmasq to make a separate network.

All I did was make the tap0 with VDE, then bridge that with eth0, and there you go: VDE switch bridged with the rest of my network

Quote:

Originally Posted by Chuck56

Granted I have to provision a separate tap interface for each guest but I rarely run more than 3 guests simultaneously so I setup 3 tap interfaces that are referenced in my consolidated guest config file.

One of the advantages of VDE is you only need one TAP device, as long as you define unique MAC addresses on your virtual NICs.

Ramurd · 09-05-2010, 06:02 AM

Got the script working in basics now:

Code:

#!/bin/ksh

# ksh is more or less required due to scoping of variables
# bash is picky and doesn't scope outside piped loops :-(

machine=${1}
inifile="manage_vm.ini"

parse_inifile()
{
	if [ "${machine}" = "list"  ]
	then
		cat ${inifile} | grep -v "^#" | grep -e "^\[.*\]$" | cut -d '[' -f 2 - | cut -d ']' -f 1
		return
	fi

	section_start=`cat ${inifile} | grep -v "^#" | grep -n "^\[${machine}\]$" | cut -d ':' -f 1`
	
	if [ -z "${section_start}" ]
	then
	        echo "No [${machine}] section found; valid sections are: "
	        cat ${inifile} | grep -v "^#" | grep -e "^\[.*\]$" | cut -d '[' -f 2 - | cut -d ']' -f 1
	        exit
	fi
	
	section_end=`cat ${inifile} | grep -v "^#" | grep -e "^$" -n | cut -d ':' -f 1 | while read num
	do
		if [ ${num} -gt ${section_start} ]
		then
			echo ${num}
		fi
	done | head -n 1`
	
	((diff=section_end - section_start))
	
	echo "Start: ${section_start}"
	echo "End  : ${section_end}"
	echo "Diff : ${diff}"
	cat ${inifile} | grep -v "^#" | tail -n +${section_start} | head -n ${diff} | while read option
	do
		echo "${#OPT[*]}: ${option}" 
		OPT[${#OPT[*]}]=${option}
	done 
}

parse_options()
{
	COUNT=0
	PARAMETERS=""
	QEMU_BIN=/usr/bin/qemu-system-x86_64

	while [ ${COUNT} -lt ${#OPT[*]} ]
	do
		((COUNT+=1)) # we can safely do this; as OPT[0] is the section header
		ARG=`echo ${OPT[${COUNT}]} | cut -d '=' -f 1` 
		VAL=`echo ${OPT[${COUNT}]} | cut -d '=' -f 2-`

		case ${ARG} in
			"")
				echo "${machine} parsed."
				;; # yes pretty silly, right?
			"qemu_bin") # with qemu_bin you can configure another qemu binary
				QEMU_BIN="${VAL}"
				;;
			"machine")
				PARAMETERS="${PARAMETERS}-M ${VAL} "
				;;
			*)
				PARAMETERS="${PARAMETERS} -${ARG} ${VAL} "
				;;
		esac
	done
	echo ${PARAMETERS}
}

main()
{
	parse_inifile
	parse_options
	
	case $1 in
		"stop")
			echo "Not implemented yet."
			;;
		"start")
			${QEMU_BIN} ${PARAMETERS}
			;;
	esac
}

if [ -z "${1}" ]
then
	echo "Usage: $0 <machine|"list"> <stop|start|restart|status>"
	return 1
fi

if [ "${1}" = "list" ]
then
	main list
	return 0
fi

if [ -z "${2}" ]
then
	echo "Usage: $0 <machine|"list"> <stop|start|restart|status>"
	return 1
fi

case ${2} in
	"stop")
		echo "Not implemented yet."
		;;
	"start")
		main start
		;;
	"status")
		echo "Not implemented yet."
		;;
	"restart")
		echo "Not implemented yet."
		;;
	*)
		echo "Invalid action: actions are: stop, start, restart or status"
		;;
esac

and here my example of an ini file:

Code:

[slack64]
monitor=stdio
smp=2
cpu=qemu64
soundhw=sb16
vga=vmware
m=1500
localtime=
hda=/qcow/Slack64.qcow2
boot=order=dc,menu=off
net=nic,vlan=0,macaddr=52:54:00:e7:91:a4,model=virtio,name="slack64"
net=vde,vlan=0
enable-kvm=
name="Linux-x86_64"
qemu_bin=/usr/bin/qemu-system-x86_64