+++ /dev/null
-#!/bin/bash -norc
-
-# Magic startup script for a UML instance. As long as unique
-# instances are started, more than one of them can be concurrently
-# in use on a single system. All their network interfaces are
-# bridged together onto the virtual bridge "virbr0" which is
-# supplied by the "libvirt" package.
-#
-# Note that a DHCP server is started for that interface. It's
-# configured in this file:
-# /etc/libvirt/qemu/networks/default.xml
-# Unfortunately what I see there serves all possible DHCP addresses,
-# so stealing them like we do here isn't really kosher. To fix
-# it, that configuration should change to serve a smaller subset
-# of the available address range.
-#
-# Each instance uses its own tun/tap device, created using the
-# "tunctl" command. The assigned tap device will correspond with
-# the guest id (a small integer representing the instance), i.e.,
-# guest id 1 uses tap1, etc. The tap device is attached to the
-# virtual bridge, which will have its own subnet associated with it.
-# The guest side of that interface will have the same subnet as the
-# bridge interface, with the bottom bits representing (normally) 100
-# more than the guest id. So for subnet 192.168.122.0/24, guest
-# id 1 will use ip 192.168.122.101, guest id 2 will use ip
-# 192.168.122.102, and so on. Because these interfaces are bridged,
-# they can all communicate with each other.
-
-# You will want to override this by setting and exporting the
-# "CEPH_TOP" environment variable to be the directory that contains
-# the "ceph-client" source tree.
-CEPH_TOP="${CEPH_TOP:-/home/elder/ceph}"
-
-# You may want to change this too, if you want guest UML instances
-# to have a diffeerent IP address range. The guest IP will be based
-# on this plus GUEST_ID (defined below).
-GUEST_IP_OFFSET="${GUEST_IP_OFFSET:-100}"
-
-#############################
-
-if [ $# -gt 1 ]; then
- echo "" >&2
- echo "Usage: $(basename $0) [guest_id]" >&2
- echo "" >&2
- echo " guest_id is a small integer (default 1)" >&2
- echo " (each UML instance needs a distinct guest_id)" >&2
- echo "" >&2
- exit 1
-elif [ $# -eq 1 ]; then
- GUEST_ID="$1"
-else
- GUEST_ID=1
-fi
-
-# This will be what the guest host calls itself.
-GUEST_HOSTNAME="uml-${GUEST_ID}"
-
-# This is the path to the boot disk image used by UML.
-DISK_IMAGE_A="${CEPH_TOP}/ceph-client/uml.${GUEST_ID}"
-if [ ! -f "${DISK_IMAGE_A}" ]; then
- echo "root disk image not found (or not a file)" >&2
- exit 2
-fi
-
-# Hostid 1 uses tun/tap device tap1, hostid 2 uses tap2, etc.
-TAP_ID="${GUEST_ID}"
-# This is the tap device used for this UML instance
-TAP="tap${TAP_ID}"
-
-# This is just used to mount an image temporarily
-TMP_MNT="/tmp/m$$"
-
-# Where to put a config file generated for this tap device
-TAP_IFUPDOWN_CONFIG="/tmp/interface-${TAP}"
-
-# Compute the HOST_IP and BROADCAST address values to use,
-# and assign shell variables with those names to their values.
-# Also compute BITS, which is the network prefix length used.
-# The NETMASK is then computed using that BITS value.
-eval $(
-ip addr show virbr0 | awk '
-/inet/ {
- split($2, a, "/")
- printf("HOST_IP=%s\n", a[1]);
- printf("BROADCAST=%s\n", $4);
- printf("BITS=%s\n", a[2]);
- exit(0);
-}')
-
-# Use bc to avoid 32-bit wrap when computing netmask
-eval $(
-echo -n "NETMASK="
-bc <<! | fmt | sed 's/ /./g'
-m = 2 ^ 32 - 2 ^ (32 - ${BITS})
-for (p = 24; p >= 0; p = p - 8)
- m / (2 ^ p) % 256
-!
-)
-
-# Now use the netmask and the host IP to compute the subnet address
-# and from that the guest IP address to use.
-eval $(
-awk '
-function from_quad(addr, a, val, i) {
- if (split(addr, a, ".") != 4)
- exit(1); # address not in dotted quad format
- val = 0;
- for (i = 1; i <= 4; i++)
- val = val * 256 + a[i];
- return val;
-}
-function to_quad(val, addr, i) {
- addr = "";
- for (i = 1; i <= 4; i++) {
- addr = sprintf("%u%s%s", val % 256, i > 1 ? "." : "", addr);
- val = int(val / 256);
- }
- if ((val + 0) != 0)
- exit(1); # value provided exceeded 32 bits
- return addr;
-}
-BEGIN {
- host_ip = from_quad("'${HOST_IP}'");
- netmask = from_quad("'${NETMASK}'");
- guest_net_ip = '${GUEST_IP_OFFSET}' + '${GUEST_ID}';
- if (and(netmask, guest_net_ip))
- exit(1); # address too big for subnet
- subnet = and(host_ip, netmask);
- guest_ip = or(subnet, guest_net_ip);
- if (guest_ip == host_ip)
- exit(1); # computed guest ip matches host ip
-
- printf("SUBNET=%s\n", to_quad(subnet));
- printf("GUEST_IP=%s\n", to_quad(guest_ip));
-}
-' < /dev/null
-)
-
-############## OK, we now know all our network parameters...
-
-# There is a series of things that need to be done as superuser,
-# so group them all into one big (and sort of nested!) sudo request.
-sudo -s <<EnD_Of_sUdO
-# Mount the boot disk for the UML and set up some configuration
-# files there.
-mkdir -p "${TMP_MNT}"
-mount -o loop "${DISK_IMAGE_A}" "${TMP_MNT}"
-
-# Arrange for loopback and eth0 to load automatically,
-# and for eth0 to have our desired network parameters.
-cat > "${TMP_MNT}/etc/network/interfaces" <<!
-# Used by ifup(8) and ifdown(8). See the interfaces(5) manpage or
-# /usr/share/doc/ifupdown/examples for more information.
-auto lo
-iface lo inet loopback
-auto eth0
-# iface eth0 inet dhcp
-iface eth0 inet static
- address ${GUEST_IP}
- netmask ${NETMASK}
- broadcast ${BROADCAST}
- gateway ${HOST_IP}
-!
-
-# Have the guest start with an appropriate host name.
-# Also record an entry for it in its own hosts file.
-echo "${GUEST_HOSTNAME}" > "${TMP_MNT}/etc/hostname"
-echo "${GUEST_IP} ${GUEST_HOSTNAME}" >> "${TMP_MNT}/etc/hosts"
-
-# The host will serve as the name server also
-cat > "${TMP_MNT}/etc/resolv.conf" <<!
-nameserver ${HOST_IP}
-!
-
-# OK, done tweaking the boot image.
-sync
-umount "${DISK_IMAGE_A}"
-rmdir "${TMP_MNT}"
-
-# Set up a config file for "ifup" and "ifdown" (on the host) to use.
-# All the backslashes below are needed because we're sitting inside
-# a double here-document...
-cat > "${TAP_IFUPDOWN_CONFIG}" <<!
-iface ${TAP} inet manual
- up brctl addif virbr0 "\\\${IFACE}"
- up ip link set dev "\\\${IFACE}" up
- pre-down brctl delif virbr0 "\\\${IFACE}"
- pre-down ip link del dev "\\\${IFACE}"
- tunctl_user $(whoami)
-!
-
-# OK, bring up the tap device using our config file
-ifup -i "${TAP_IFUPDOWN_CONFIG}" "${TAP}"
-
-EnD_Of_sUdO
-
-# Finally ready to launch the UML instance.
-./linux \
- umid="${GUEST_HOSTNAME}" \
- ubda="${DISK_IMAGE_A}" \
- eth0="tuntap,${TAP}" \
- mem=1024M
-
-# When we're done, clean up. Bring down the tap interface and
-# delete the config file.
-#
-# Note that if the above "./linux" crashes, you'll need to run the
-# following commands manually in order to clean up state.
-sudo ifdown -i "${TAP_IFUPDOWN_CONFIG}" "${TAP}"
-sudo rm -f "${TAP_IFUPDOWN_CONFIG}"
-
-exit 0
Code Review / stor4nfv.git / blobdiff