take the bridge-creation code out in lbuild-bridge.sh so we can reuse this in regular...

[build.git] / lbuild-bridge.sh

diff --git a/lbuild-bridge.sh b/lbuild-bridge.sh
new file mode 100644 (file)
index 0000000..ecf218b
--- /dev/null
+++ b/lbuild-bridge.sh
@@ -0,0 +1,134 @@
+#!/bin/bash
+
+# taking this bridge-initialization code out of lbuild-initvm.sh 
+# so we can use it on our libvirt/lxc local infra 
+# there's something very similar in 
+# tests/system/template-qemu/qemu-bridge-init
+# that the current code was actually based on, but 
+# nobody was ever bold enough to reconcile these two 
+
+# hard-wired 
+DEFAULT_PUBLIC_BRIDGE=br0
+
+##############################
+# use /proc/net/dev instead of a hard-wired list
+function gather_interfaces () {
+    python <<EOF
+for line in file("/proc/net/dev"):
+    if ':' not in line: continue
+    ifname=line.replace(" ","").split(":")[0]
+    if ifname.find("lo")==0: continue
+    if ifname.find("br")==0: continue
+    if ifname.find("virbr")==0: continue
+    if ifname.find("veth")==0: continue
+    if ifname.find("tap")==0: continue
+    print ifname
+EOF
+}
+
+function discover_interface () {
+    for ifname in $(gather_interfaces); do
+       ip link show $ifname | grep -qi 'state UP' && { echo $ifname; return; }
+    done
+    # still not found ? that's bad
+    echo unknown
+}
+
+#################### bridge initialization
+function create_bridge_if_needed() {
+
+    # turn on verbosity
+    set -x
+
+    public_bridge=$1; shift
+
+    # already created ? - we're done
+    ip addr show $public_bridge >& /dev/null && {
+       echo "Bridge already set up - skipping create_bridge_if_needed"
+       return 0
+    }
+
+    # find out the physical interface to bridge onto
+    if_lan=$(discover_interface)
+
+    ip addr show $if_lan &>/dev/null || {
+        echo "Cannot use interface $if_lan - exiting"
+        exit 1
+    }
+
+    #################### bride initialization
+    check_yum_installed bridge-utils
+
+    echo "========== $COMMAND: entering create_bridge - beg"
+    hostname
+    uname -a
+    ip addr show
+    ip route
+    echo "========== $COMMAND: entering create_bridge - end"
+
+    # disable netfilter calls for bridge interface (they cause panick on 2.6.35 anyway)
+    #
+    # another option would be to accept the all forward packages for
+    # bridged interface like: -A FORWARD -m physdev --physdev-is-bridged -j ACCEPT
+    sysctl net.bridge.bridge-nf-call-iptables=0
+    sysctl net.bridge.bridge-nf-call-ip6tables=0
+    sysctl net.bridge.bridge-nf-call-arptables=0
+
+    
+    #Getting host IP/masklen
+    address=$(ip addr show $if_lan | grep -v inet6 | grep inet | head --lines=1 | awk '{print $2;}')
+    [ -z "$address" ] && { echo "ERROR: Could not determine IP address for $if_lan" ; exit 1 ; }
+
+    broadcast=$(ip addr show $if_lan | grep -v inet6 | grep inet | head --lines=1 | awk '{print $4;}')
+    [ -z "$broadcast" ] && echo "WARNING: Could not determine broadcast address for $if_lan"
+
+    gateway=$(ip route show | grep default | awk '{print $3;}')
+    [ -z "$gateway" ] && echo "WARNING: Could not determine gateway IP"
+
+
+    # creating the bridge
+    echo "Creating public bridge interface $public_bridge"
+    brctl addbr $public_bridge
+    brctl addif $public_bridge $if_lan
+    echo "Activating promiscuous mode if_lan=$if_lan"
+    ip link set $if_lan up promisc on
+    sleep 2
+    # rely on dhcp to re assign IP.. 
+    echo "Starting dhclient on $public_bridge"
+    dhclient $public_bridge
+    sleep 1
+
+    #Reconfigure the routing table
+    echo "Configuring gateway=$gateway"
+    ip route add default via $gateway dev $public_bridge
+    ip route del default via $gateway dev $if_lan
+    # at this point we have an extra route like e.g.
+    ## ip route show
+    #default via 138.96.112.250 dev br0
+    #138.96.112.0/21 dev em1  proto kernel  scope link  src 138.96.112.57
+    #138.96.112.0/21 dev br0  proto kernel  scope link  src 138.96.112.57
+    #192.168.122.0/24 dev virbr0  proto kernel  scope link  src 192.168.122.1
+    route_dest=$(ip route show | grep -v default | grep "dev $public_bridge" | awk '{print $1;}')
+    ip route del $route_dest dev $if_lan
+
+    echo "========== $COMMAND: exiting create_bridge - beg"
+    ip addr show
+    ip route show
+    echo "========== $COMMAND: exiting create_bridge - end"
+
+    # for safety
+    sleep 3
+    return 0
+
+}
+
+function main () {
+    if [[ -n "$@" ]] ; then 
+       public_bridge="$1"; shift
+    else
+       public_bridge="$DEFAULT_PUBLIC_BRIDGE"
+    fi
+    create_bridge_if_needed $public_bridge
+}
+
+main "$@"