mk-network-dot

#!/bin/sh

topdir=$PWD
workdir=$(mktemp -d networkXXXXXX)
trap "cd $topdir; rm -rf $workdir" EXIT

cd $workdir

> nodes
> edges
> peers

# Get a list of running instances and their associated
# interfaces.
virsh list --name | while read instance; do
	[ "$instance" ] || continue

	echo "$instance instance global" >> nodes

	for dev in $(virsh dumpxml $instance |
		xmllint --xpath '//interface/target/@dev' -); do
		dev=${dev#dev=\"}
		dev=${dev%\"}
		echo "$instance $dev" >> edges
	done
done

# Gather network device information from the global
# namespace.
sh $topdir/ns-get-devs global

# Gather network device information for all of the
# active namespaces.
ip netns | while read ns; do
	ip netns exec $ns sh $topdir/ns-get-devs $ns
done

# Get information about OVS ports
> seen
ovs-vsctl list-br |
while read brdev; do
	ovs-vsctl list-ports $brdev |
	while read port; do
		# Only handle interfaces that we haven't seen
		# previously.
		grep -q "$port" nodes && continue

		porttype=$(ovs-vsctl get Interface $port type)
		
		if [ "$porttype" = patch ]; then
			porttype=ovspatch
			peer=$(ovs-vsctl get Interface $port options:peer)

			if [ "$peer" ] && ! grep -q $peer seen; then
				echo "$port $peer" >> edges
			fi
		elif [ "$porttype" = gre ] || [ "$porttype" = vxlan ]; then
			porttype=ovstun
			peer=$(ovs-vsctl get Interface $port options:remote_ip)
			if [ "$peer" ]; then
				echo "$port ${peer//\"/}" >> edges
				echo "${peer//\"/} remote global" >> nodes
			fi
		fi

		echo "$port $porttype global" >> nodes
		echo $port >> seen
	done
done

# Add edges for veth peer inferfaces.
> seen
while read dev ifindex peer_ifindex; do
	peer_dev=$(awk -v peer=$peer_ifindex '$2 == peer {print $1}' peers)
	grep -q $peer_dev seen && continue

	echo "$dev $peer_dev" >> edges
	echo $dev >> seen
done < peers

# Generates dot output.

cat <<EOF
graph network {
	rankdir=LR
EOF

# Emit device nodes by namespace
sort -k3,3 -k2,2 -k1,1 nodes | awk '
	$3 != "global" && $3 != lastns {
		if (lastns)
			print "}"
		printf "subgraph \"cluster_%s\" {\n", $3
		printf "  label=\"%s\"\n", $3
		lastns=$3
	}

	{
		style="filled"
		shape="oval"
		color="grey50"
	}

	# Set node styles.
	$2 == "instance"	{shape="box"; color="tomato"}
	$2 == "ovsbridge"	{color="lightblue"}
	$2 == "bridge"		{color="olivedrab"}
	$2 == "veth"		{color="lightgrey"}
	$2 == "ovspatch"	{shape="cds"; color="gold"}
	$2 == "ovstun"		{shape="cds"; color="thistle"}
	$2 == "remote"		{shape="box"; style="solid"; color="black"}

	{
		printf "\"%s\" [shape=%s,style=%s,color=%s]\n", $1, shape, style, color
	}

	END {
		if (lastns != "global")
			print "}"
	}
'

# Emit all the edges.
awk '
	{printf "\"%s\" -- \"%s\"\n", $1, $2}
' edges

cat <<EOF
}
EOF