weave/weave

#!/bin/sh
set -e

[ -n "$WEAVE_DEBUG" ] && set -x

SCRIPT_VERSION="(unreleased version)"
if [ "$SCRIPT_VERSION" = "(unreleased version)" ] ; then
    IMAGE_VERSION=latest
else
    IMAGE_VERSION=$SCRIPT_VERSION
fi
IMAGE_VERSION=${VERSION:-$IMAGE_VERSION}

# These are needed for remote execs, hence we introduce them here
DOCKERHUB_USER=${DOCKERHUB_USER:-weaveworks}
BASE_EXEC_IMAGE=$DOCKERHUB_USER/weaveexec
EXEC_IMAGE=$BASE_EXEC_IMAGE:$IMAGE_VERSION
PROXY_HOST=${PROXY_HOST:-$(echo "${DOCKER_HOST#tcp://}" | cut -s -d: -f1)}
PROXY_HOST=${PROXY_HOST:-127.0.0.1}

# Define some regular expressions for matching addresses.
# The regexp here is far from precise, but good enough.
IP_REGEXP="[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"
CIDR_REGEXP="$IP_REGEXP/[0-9]{1,2}"

usage() {
    echo "Usage:"
    echo "weave setup"
    echo "weave launch       [-password <password>] [-nickname <nickname>] [-nodiscovery]"
    echo "                       [-iprange <cidr> [-ipsubnet <cidr>]] <peer> ..."
    echo "weave launch-dns   [<addr>]"
    echo "weave launch-proxy [-D <endpoint>] [-H <endpoint>]"
    echo "                       [--with-dns | --without-dns] [--with-ipam]"
    echo "weave connect      [--replace] [<peer> ...]"
    echo "weave forget       <peer> ..."
    echo "weave run          [--with-dns | --without-dns] [<addr> ...] <docker run args> ..."
    echo "weave start        [<addr> ...] <container_id>"
    echo "weave attach       [<addr> ...] <container_id>"
    echo "weave detach       [<addr> ...] <container_id>"
    echo "weave dns-add      <ip_address> [<ip_address> ...] <container_id> [-h <fqdn>]"
    echo "weave dns-remove   <ip_address> [<ip_address> ...] <container_id> [-h <fqdn>]"
    echo "weave expose       [<addr> ...] [-h <fqdn>]"
    echo "weave hide         [<addr> ...]"
    echo "weave ps           [<container_id> ...]"
    echo "weave status"
    echo "weave proxy-env"
    echo "weave proxy-config"
    echo "weave version"
    echo "weave stop"
    echo "weave stop-dns"
    echo "weave stop-proxy"
    echo "weave reset"
    echo "weave rmpeer       <peer_id>"
    echo
    echo "where <peer>     = <ip_address_or_fqdn>[:<port>]"
    echo "      <cidr>     = <ip_address>/<routing_prefix_length>"
    echo "      <addr>     = [ip:]<cidr> | net:<cidr> | net:default"
    echo "      <endpoint> = [tcp://][<ip_address>]:<port>"
    echo "      <peer_id>  = <nickname> or weave internal peer ID"
    exit 1
}

exec_remote() {
    docker $DOCKER_CLIENT_ARGS run --rm --privileged --net=host \
        -v /var/run/docker.sock:/var/run/docker.sock \
        -v /proc:/hostproc \
        -e PROCFS=/hostproc \
        -e DOCKERHUB_USER="$DOCKERHUB_USER" \
        -e VERSION \
        -e WEAVE_DEBUG \
        -e WEAVE_DOCKER_ARGS \
        -e WEAVEDNS_DOCKER_ARGS \
        -e WEAVEPROXY_DOCKER_ARGS \
        -e WEAVE_PASSWORD \
        -e WEAVE_PORT \
        -e WEAVE_CONTAINER_NAME \
        -e DOCKER_BRIDGE \
        -e PROXY_HOST="$PROXY_HOST" \
        $WEAVEEXEC_DOCKER_ARGS $EXEC_IMAGE --local "$@"
}

check_docker_version() {
    if ! DOCKER_VERSION=$(docker -v | sed -n -e 's|^Docker version \([0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\).*|\1|p') || [ -z "$DOCKER_VERSION" ] ; then
        echo "ERROR: Unable to parse docker version" >&2
        exit 1
    fi

    # guard against https://github.com/docker/docker/issues/8632
    if [ "$DOCKER_VERSION" = "1.3.0" ] ; then
        echo "You are running Docker version $DOCKER_VERSION, which contains a bug that prevents weave from working properly. Please upgrade." >&2
        exit 1
    fi
}

is_cidr() {
    echo "$1" | grep -E "^$CIDR_REGEXP$" >/dev/null
}

collect_cidr_args() {
    CIDR_ARGS=""
    CIDR_ARG_COUNT=0
    while [ "$1" = "net:default" ] || is_cidr "$1" || is_cidr "${1#ip:}" || is_cidr "${1#net:}" ; do
        CIDR_ARGS="$CIDR_ARGS ${1#ip:}"
        CIDR_ARG_COUNT=$((CIDR_ARG_COUNT + 1))
        shift 1
    done
}

is_ip() {
    echo "$1" | grep -E "^$IP_REGEXP$" >/dev/null
}

collect_ip_args() {
    IP_ARGS=""
    IP_COUNT=0
    while is_ip "$1" ; do
        IP_ARGS="$IP_ARGS $1"
        IP_COUNT=$((IP_COUNT + 1))
        shift 1
    done
}

dns_arg_count() {
    if [ "$1" = "--with-dns" -o "$1" = "--without-dns" ]; then
        echo 1
    else
        echo 0
    fi
}

# "run" is a special case because we want to use docker directly,
# rather than the docker in $EXEC_IMAGE remotely. That's because we
# are passing arbitrary arguments on to docker run, and we can't rely
# on our baked-in docker to support those arguments.
if [ "$1" = "run" ] ; then
    shift 1
    check_docker_version
    if [ "$1" != "--without-dns" ] ; then
      DNS_ARGS=$(exec_remote dns-args "$@" || true)
    fi
    shift $(dns_arg_count "$@")
    collect_cidr_args "$@"
    shift $CIDR_ARG_COUNT
    CONTAINER=$(docker $DOCKER_CLIENT_ARGS run $DNS_ARGS -d "$@")
    exec_remote attach $CIDR_ARGS --or-die $CONTAINER
    echo $CONTAINER
    exit 0
elif [ "$1" != "--local" ] ; then
    exec_remote "$@"
    exit $?
fi

shift 1

BASE_IMAGE=$DOCKERHUB_USER/weave
BASE_DNS_IMAGE=$DOCKERHUB_USER/weavedns
IMAGE=$BASE_IMAGE:$IMAGE_VERSION
DNS_IMAGE=$BASE_DNS_IMAGE:$IMAGE_VERSION

PROCFS=${PROCFS:-/proc}
DOCKER_BRIDGE=${DOCKER_BRIDGE:-docker0}
CONTAINER_NAME=${WEAVE_CONTAINER_NAME:-weave}
DNS_CONTAINER_NAME=weavedns
BRIDGE=weave
CONTAINER_IFNAME=ethwe
MTU=65535
PORT=${WEAVE_PORT:-6783}
HTTP_PORT=6784
DNS_HTTP_PORT=6785
DNS_HTTP_IFNAME=eth0
PROXY_PORT=12375
PROXY_CONTAINER_NAME=weaveproxy


######################################################################
# general helpers; independent of docker and weave
######################################################################

# utility function to check whether a command can be executed by the shell
# see http://stackoverflow.com/questions/592620/how-to-check-if-a-program-exists-from-a-bash-script
command_exists() {
    command -v $1 >/dev/null 2>&1
}

run_iptables() {
    # -w is recent addition to iptables
    if [ -z "$CHECKED_IPTABLES_W" ] ; then
        if iptables -S -w >/dev/null 2>&1 ; then
            IPTABLES_W=-w
        fi
        CHECKED_IPTABLES_W=1
    fi

    iptables $IPTABLES_W "$@"
}

# Add a rule to iptables, if it doesn't exist already
add_iptables_rule() {
    IPTABLES_TABLE="$1"
    shift 1
    if ! run_iptables -t $IPTABLES_TABLE -C "$@" >/dev/null 2>&1 ; then
        run_iptables -t $IPTABLES_TABLE -A "$@" >/dev/null
    fi
}

# Delete a rule from iptables, if it exist
delete_iptables_rule() {
    IPTABLES_TABLE="$1"
    shift 1
    if run_iptables -t $IPTABLES_TABLE -C "$@" >/dev/null 2>&1 ; then
        run_iptables -t $IPTABLES_TABLE -D "$@" >/dev/null
    fi
}

# Configure the ARP cache parameters for the given interface.  This
# makes containers react more quickly to a change in the MAC address
# associated with an IP address.
configure_arp_cache() {
    $2 sh -c "echo 5 >/proc/sys/net/ipv4/neigh/$1/base_reachable_time &&
              echo 2 >/proc/sys/net/ipv4/neigh/$1/delay_first_probe_time &&
              echo 1 >/proc/sys/net/ipv4/neigh/$1/ucast_solicit"
}

# Send out an unsolicated ARP response to update ARP cache entries
# accross the weave network.  We do this in addition to
# configure_arp_cache because a) with those ARP cache settings it
# still takes a few seconds to correct a stale ARP mapping, and b)
# there is a kernel bug that means that the base_reachable_time
# setting is not promptly obeyed
# (<https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4bf6980dd0328530783fd657c776e3719b421d30>>).
arp_update() {
    # It's not the end of the world if this doesn't run - we configure
    # ARP caches so that stale entries will be noticed quickly.
    if command_exists arping ; then
        $3 arping -U -q -I $1 -c 1 ${2%/*}
    fi
}

# Generate a random MAC value
random_mac() {
    # In the first byte of the MAC, the 'multicast' bit should be
    # clear and 'locally administered' bit should be set.  All other
    # bits should be random.
    od -txC -An -N6 /dev/urandom | ( read a b c d e f && printf "%02x:$b:$c:$d:$e:$f" $((0x$a & ~1 | 2)) )
}

######################################################################
# weave and docker specific helpers
######################################################################

create_bridge() {
    if [ ! -d /sys/class/net/$BRIDGE ] ; then
        ip link add name $BRIDGE type bridge
        # Set a random MAC address on the bridge.  Current Linux
        # kernels already do this when creating a bridge, but there
        # are rumours it was not always so.
        ip link set dev $BRIDGE address $(random_mac)
        # Attempting to set the bridge MTU to a high value directly
        # fails. Bridges take the lowest MTU of their interfaces. So
        # instead we create a temporary interface with the desired
        # MTU, attach that to the bridge, and then remove it again.
        ip link add name v${CONTAINER_IFNAME}du mtu $MTU type dummy
        ip link set dev v${CONTAINER_IFNAME}du master $BRIDGE
        ip link del dev v${CONTAINER_IFNAME}du
        # Drop traffic from Docker bridge to Weave; it can break subnet isolation
        if [ "$DOCKER_BRIDGE" != "$BRIDGE" ] ; then
            # Note using -I to insert ahead of Docker's bridge rules
            run_iptables -t filter -I FORWARD -i $DOCKER_BRIDGE -o $BRIDGE -j DROP
        fi
        # Work around the situation where there are no rules allowing traffic
        # across our bridge. E.g. ufw
        add_iptables_rule filter FORWARD -i $BRIDGE -o $BRIDGE -j ACCEPT
        # create a chain for masquerading
        run_iptables -t nat -N WEAVE >/dev/null 2>&1 || true
        add_iptables_rule nat POSTROUTING -j WEAVE
    fi

    [ "$1" != "--without-ethtool" ] && ethtool -K $BRIDGE tx off >/dev/null

    ip link set dev $BRIDGE up

    # Configure the ARP cache parameters on the bridge interface for
    # the sake of 'weave expose'
    configure_arp_cache $BRIDGE
}

destroy_bridge() {
    [ -d /sys/class/net/$BRIDGE ] && ip link del dev $BRIDGE
    if [ "$DOCKER_BRIDGE" != "$BRIDGE" ] ; then
        run_iptables -t filter -D FORWARD -i $DOCKER_BRIDGE -o $BRIDGE -j DROP 2>/dev/null || true
    fi
    run_iptables -t filter -D FORWARD -i $BRIDGE -o $BRIDGE -j ACCEPT 2>/dev/null || true
    run_iptables -t nat -F WEAVE >/dev/null 2>&1 || true
    run_iptables -t nat -D POSTROUTING -j WEAVE >/dev/null 2>&1 || true
    run_iptables -t nat -X WEAVE >/dev/null 2>&1 || true
}

docker_bridge_ip() {
    DOCKER_BRIDGE_IP=$(ip -4 addr show dev $DOCKER_BRIDGE | grep -m1 -o 'inet [.0-9]*')
    DOCKER_BRIDGE_IP=${DOCKER_BRIDGE_IP#inet }
}

# the following borrows from https://github.com/jpetazzo/pipework

# Set $CONTAINER_PID to the PID of container $1, $LOCAL_IFNAME and
# $GUEST_IFNAME to suitable names for two ends of a veth pair, specific
# to the container, and execute args $2 $3 ... as a command. If an error
# is caused by container dying, swallow output from error.
with_container_netns() {
    CONTAINER="$1"
    CONTAINER_PID=$(docker inspect --format='{{.State.Pid}}' $CONTAINER)

    if [ "$CONTAINER_PID" = 0 ] ; then
        echo "Container $CONTAINER not running." >&2
        exit 1
    fi

    if [ "$CONTAINER_PID" = "<no value>" ] ; then
        echo "Container $CONTAINER unknown to Docker." >&2
        exit 1
    fi

    LOCAL_IFNAME="v${CONTAINER_IFNAME}pl${CONTAINER_PID}"
    GUEST_IFNAME="v${CONTAINER_IFNAME}pg${CONTAINER_PID}"
    IP_TMPOUT=/tmp/weave_ip_out_$$
    IP_TMPERR=/tmp/weave_ip_err_$$
    rm -f $IP_TMPOUT $IP_TMPERR

    # Run the wrapped command
    STATUS=0
    shift 1
    if ! "$@" >$IP_TMPOUT 2>$IP_TMPERR ; then
        STATUS=1
        if [ ! -d $PROCFS/$CONTAINER_PID ] ; then
            echo "Container $CONTAINER died" >&2
        else
            echo "Failure during network configuration for container $CONTAINER:" >&2
            cat $IP_TMPERR >&2
        fi
    else
        cat $IP_TMPOUT
        cat $IP_TMPERR >&2
    fi
    rm -f $IP_TMPOUT $IP_TMPERR
    return $STATUS
}

with_container_netns_or_die() {
    if ! with_container_netns "$@" >/dev/null ; then
        docker kill $1 >/dev/null 2>&1 || true
        exit 1
    fi
}

# Execute arguments as a command within the network namespace of $CONTAINER_PID
netnsenter() {
    nsenter --net=$PROCFS/$CONTAINER_PID/ns/net "$@"
}

connect_container_to_bridge() {
    if [ -h "$PROCFS/$CONTAINER_PID/ns/net" -a -h "$PROCFS/$$/ns/net" -a "$(readlink $PROCFS/$CONTAINER_PID/ns/net)" = "$(readlink $PROCFS/$$/ns/net)" ] ; then
        echo "Container is running in the host network namespace, and therefore cannot be" >&2
        echo "connected to weave. Perhaps the container was started with --net=host." >&2
        return 1
    fi
    ip link add name $LOCAL_IFNAME mtu $MTU type veth peer name $GUEST_IFNAME mtu $MTU || return 1

    if ! ethtool -K $GUEST_IFNAME tx off >/dev/null ||
        ! ip link set $LOCAL_IFNAME master $BRIDGE ||
        ! ip link set $LOCAL_IFNAME up ||
        ! ip link set $GUEST_IFNAME netns $PROCFS/$CONTAINER_PID/ns/net ; then
        # failed before we assigned the veth to the container's
        # namespace
        ip link del $LOCAL_IFNAME type veth || true
        return 1
    fi

    if ! netnsenter ip link set $GUEST_IFNAME name $CONTAINER_IFNAME ||
       ! configure_arp_cache $CONTAINER_IFNAME "netnsenter" ; then
        return 1
    fi
}

ask_version() {
    if ! DOCKERIMAGE=$(docker inspect --format='{{.Image}}' $1 2>/dev/null) ; then
            if ! DOCKERIMAGE=$(docker inspect --format='{{.Id}}' $2 2>/dev/null) ; then
                echo "Unable to find $2 image." >&2
            fi
    fi
    [ -n "$DOCKERIMAGE" ] && docker run --rm $DOCKERIMAGE --version
}

######################################################################
# functions invoked through with_container_netns
######################################################################

launch() {
    if ! netnsenter ip link show eth0 >/dev/null ; then
        echo "Perhaps you are running the docker daemon with container networking disabled (-b=none)." >&2
        return 1
    fi
    connect_container_to_bridge &&
        netnsenter ethtool -K eth0 tx off >/dev/null &&
        netnsenter ip link set $CONTAINER_IFNAME up
}

attach() {
    if netnsenter ip link show $CONTAINER_IFNAME >/dev/null 2>&1 ; then
        for ADDR in "$@" ; do
            # container already has the expected network interface, so assume we set it up already;
            # just add the IP address.
            if netnsenter ip addr show dev $CONTAINER_IFNAME | grep -F $ADDR >/dev/null ; then
                # address was there already
                continue
            fi
            netnsenter ip addr add $ADDR dev $CONTAINER_IFNAME || return 1
        done

        return 0
    fi

    connect_container_to_bridge || return 1

    for ADDR in "$@" ; do
        netnsenter ip addr add $ADDR dev $CONTAINER_IFNAME || return 1
    done

    netnsenter ip link set $CONTAINER_IFNAME up || return 1

    # Route multicast packets across the weave network.
    if ! netnsenter ip route show | grep '^224\.0\.0\.0/4' >/dev/null ; then
        netnsenter ip route add 224.0.0.0/4 dev $CONTAINER_IFNAME
    fi

    arp_update $CONTAINER_IFNAME $1 "netnsenter"
}

detach() {
    netnsenter ip link show $CONTAINER_IFNAME >/dev/null 2>&1 || return 0

    for ADDR in "$@" ; do
        if ! netnsenter ip addr show dev $CONTAINER_IFNAME | grep -F $ADDR >/dev/null ; then
            # address is not there, leave the device alone
            continue
        fi
        netnsenter ip addr del $ADDR dev $CONTAINER_IFNAME || return 1
    done

    if [ -n "$(netnsenter ip -f inet addr show dev $CONTAINER_IFNAME)" ] ; then
        # other addresses are left, leave the device alone
        return 0
    fi

    # Deleting the interface will delete the multicast route we set up
    netnsenter ip link del $CONTAINER_IFNAME type veth
}

container_weave_addrs() {
    netnsenter ip addr show dev $CONTAINER_IFNAME
}

######################################################################
# functions for interacting with containers
######################################################################

# Check that a container named $1 with image $2 is not running
check_not_running() {
    case $(docker inspect --format='{{.State.Running}} {{.Config.Image}}' $1 2>/dev/null) in
        "true $2")
            echo "$1 is already running." >&2
            exit 1
            ;;
        "true $2:"*)
            echo "$1 is already running." >&2
            exit 1
            ;;
        "false $2")
            docker rm $1 >/dev/null
            ;;
        "false $2:"*)
            docker rm $1 >/dev/null
            ;;
        true*)
            echo "Found another running container named '$1'. Aborting." >&2
            exit 1
            ;;
        false*)
            echo "Found another container named '$1'. Aborting." >&2
            exit 1
            ;;
    esac
}

stop() {
    if ! docker stop $1 >/dev/null 2>&1 ; then
        echo "$2 is not running." >&2
    fi
    docker rm -f $1 >/dev/null 2>&1 || true
}

# Given a container name or short ID in $1, ensure the specified
# container is running and then print its full ID to stdout. If
# it's not running or doesn't exist, print an error to stderr and
# return with an indicative non-zero exit code.
container_id() {
    if ! status=$(docker inspect --format='{{.State.Running}} {{.Id}}' $1 2>/dev/null) ; then
        echo "Error: No such container: $1" >&2
        return 1
    fi
    case "$status" in
        true*)
            echo "${status#true }"
            ;;
        *)
            echo "$1 container is not running." >&2
            return 2
            ;;
    esac
}

container_ip() {
    if ! status=$(docker inspect --format='{{.State.Running}} {{.NetworkSettings.IPAddress}}' $1 2>/dev/null) ; then
        echo "$2" >&2
        return 1
    fi
    case "$status" in
        "true ")
            echo "$1 container has no IP address; is Docker networking enabled?" >&2
            return 1
            ;;
        true*)
            CONTAINER_IP="${status#true }"
            ;;
        *)
            echo "$3" >&2
            return 1
            ;;
    esac
}

http_call_ip() {
    ip="$1"
    port="$2"
    http_verb="$3"
    url="$4"
    shift 4
    curl --connect-timeout 3 -s -S -X $http_verb "$@" http://$ip:$port$url
}

# Call url $4 with http verb $3 on container $1 at port $2
http_call() {
    HTTP_CALL_CONTAINER=$1
    container_ip $HTTP_CALL_CONTAINER \
        "$HTTP_CALL_CONTAINER container is not present. Have you launched it?" \
        "$HTTP_CALL_CONTAINER container is not running." \
        || return 1
    shift 1
    if ! http_call_ip $CONTAINER_IP "$@" ; then
        echo "Call to $HTTP_CALL_CONTAINER failed." >&2
        return 1
    fi
}

call_weave() {
    http_call $CONTAINER_NAME $HTTP_PORT "$@"
}

call_dns() {
    http_call $DNS_CONTAINER_NAME $DNS_HTTP_PORT "$@"
}

# Wait until container $1 is alive enough to respond to "GET /status"
# http request on its docker-assigned IP, port $2
wait_for_status() {
    container_ip $1 "$1 container has died." "$1 container has died." || return 1
    while true ; do
        http_call_ip $CONTAINER_IP $2 GET /status >/dev/null 2>&1 && return 0
        if ! container_id $1 >/dev/null 2>&1 ; then
            echo "$1 container has died." >&2
            return 1
        fi
        sleep 1
    done
}

# Wait until container $1 outputs a line containing $2 in its log
wait_for_log() {
    fifo=/tmp/tmpfifo.$$
    mkfifo $fifo || exit 1
    docker logs -f $1 2>/dev/null >$fifo &
    res=0
    grep -q "$2" $fifo || res=1
    kill $! 2>/dev/null || true
    rm $fifo
    [ $res -eq 1 ] && echo "$1 container has died." >&2
    return $res
}

# Call $1 for all containers, passing container ID, all MACs and all IPs
with_container_addresses() {
    COMMAND=$1
    shift 1
    for CONTAINER_ID in "$@" ; do
        if [ "$CONTAINER_ID" = "weave:expose" ] ; then
            ADDRS_CMD="ip addr show dev $BRIDGE"
        else
            ADDRS_CMD="with_container_netns $CONTAINER_ID container_weave_addrs"
        fi
        if CONTAINER_ADDRS=$($ADDRS_CMD 2>/dev/null) ; then
            CONTAINER_MAC=$(echo "$CONTAINER_ADDRS" | grep -o 'link/ether .*' | cut -d ' ' -f 2)
            CONTAINER_IPS=$(echo "$CONTAINER_ADDRS" | grep -o 'inet .*'       | cut -d ' ' -f 2)
            $COMMAND "$CONTAINER_ID" "$CONTAINER_MAC" "$CONTAINER_IPS"
        fi
    done
}

echo_addresses() {
    echo $1 $2 $3
}

peer_args() {
  res=''
  sep=''
  for p in "$@" ; do
    res="$res${sep}peer=$p"
    sep="&"
  done
  echo "$res"
}

######################################################################
# weaveDNS helpers
######################################################################

# Memoized function to query the weaveDNS server for our dns domain.
dns_domain() {
  DNS_DOMAIN=${DNS_DOMAIN:-$(call_dns GET /domain 2>/dev/null || true)}
  DNS_DOMAIN=${DNS_DOMAIN:-weave.local.}
  echo $DNS_DOMAIN
}

dns_args() {
    if [ \( "$DOCKER_VERSION_MAJOR" -lt 1 \) -o \
        \( "$DOCKER_VERSION_MAJOR" -eq 1 -a \
        "$DOCKER_VERSION_MINOR" -lt 3 \) ] ; then
        # Versions prior to 1.2.0 cannot parse `--dns-search=.`, and
        # versions prior to 1.3.0 fail to include the domain when
        # setting the hostname, so lookups for non-fully-qualified
        # names fail.
        echo "ERROR: Need Docker 1.3.0 or later to configure container DNS; you are running $DOCKER_VERSION" >&2
        exit 1
    fi
    docker_bridge_ip
    NAME_ARG=""
    HOSTNAME_SPECIFIED=
    DNS_SEARCH_SPECIFIED=
    WITH_DNS=
    WITHOUT_DNS=
    while [ $# -gt 0 ] ; do
        case "$1" in
            --dns-search=*)
                DNS_SEARCH_SPECIFIED=1
                ;;
            --name)
                NAME_ARG="$2"
                shift
                ;;
            --name=*)
                NAME_ARG="${1#*=}"
                ;;
            -h|--hostname|--hostname=*)
                HOSTNAME_SPECIFIED=1
                ;;
            --with-dns)
                WITH_DNS=1
                ;;
            --without-dns)
                WITHOUT_DNS=1
                ;;
        esac
        shift
    done
    [ -n "$WITHOUT_DNS" ] && return 0
    if [ -z "$WITH_DNS" ] ; then
        check_running $DNS_CONTAINER_NAME 2>/dev/null || return 0
    fi
    DNS_ARGS="--dns $DOCKER_BRIDGE_IP"
    if [ -n "$NAME_ARG" -a -z "$HOSTNAME_SPECIFIED" ] ; then
        DOMAIN=$(dns_domain)
        DNS_ARGS="$DNS_ARGS --hostname=$NAME_ARG.${DOMAIN%.}"
        HOSTNAME_SPECIFIED=1
    fi
    if [ -z "$DNS_SEARCH_SPECIFIED" ] ; then
      if [ -z "$HOSTNAME_SPECIFIED" ] ; then
        DNS_ARGS="$DNS_ARGS --dns-search=$(dns_domain)"
      else
        DNS_ARGS="$DNS_ARGS --dns-search=."
      fi
    fi
}

# Print an error to stderr and return with an indicative exit status
# if the container $1 does not exist or isn't running.
check_running() {
    if ! STATUS=$(docker inspect --format='{{.State.Running}}' $1 2>/dev/null); then
        echo  "$1 container is not present. Have you launched it?" >&2
        return 1
    elif [ "$STATUS" != "true" ] ; then
        echo "$1 container is not running." >&2
        return 2
    fi
}

# Execute $@ only if the weaveDNS container is running
when_dns_running() {
    if check_running $DNS_CONTAINER_NAME 2>/dev/null; then
        "$@"
    fi
}

# Iff the container in $1 has an FQDN, invoke $2 as a command passing
# the container as the first argument, the FQDN as the second argument
# and $3.. as additional arguments
with_container_fqdn() {
    CONTAINER="$1"
    COMMAND="$2"
    shift 2

    CONTAINER_FQDN=$(docker inspect --format='{{.Config.Hostname}}.{{.Config.Domainname}}' $CONTAINER 2>/dev/null) || return 0

    if echo "$CONTAINER_FQDN" | grep -Eq '[^.]+\..+' ; then
        $COMMAND "$CONTAINER" "$CONTAINER_FQDN" "$@"
    fi
}

# Register FQDN in $2 as names for addresses $3.. under full container ID $1
put_dns_fqdn() {
    CONTAINER_ID="$1"
    FQDN="$2"
    shift 2

    for ADDR in "$@" ; do
        call_dns PUT /name/$CONTAINER_ID/${ADDR%/*} --data-urlencode fqdn=$FQDN || true
    done
}

# Delete all names for addresses $3.. under full container ID $1
delete_dns() {
    CONTAINER_ID="$1"
    shift 1

    for ADDR in "$@" ; do
        call_dns DELETE /name/$CONTAINER_ID/${ADDR%/*} || true
    done
}

# Delete any FQDNs $2 from addresses $3.. under full container ID $1
delete_dns_fqdn() {
    CONTAINER_ID="$1"
    FQDN="$2"
    shift 2

    for ADDR in "$@" ; do
        call_dns DELETE /name/$CONTAINER_ID/${ADDR%/*}?fqdn=$FQDN || true
    done
}

# Tell the newly-started weaveDNS about existing weave IPs
populate_dns() {
    if ! wait_for_status $DNS_CONTAINER_NAME $DNS_HTTP_PORT ; then
        echo "If running, it will not be pre-populated." >&2
        return 0
    fi
    for CONTAINER in $(docker ps -q --no-trunc) ; do
        if CONTAINER_IPS=$(with_container_netns $CONTAINER container_weave_addrs 2>&1 | sed -n -e 's/inet \([^/]*\)\/\(.*\)/\1/p') ; then
            with_container_fqdn $CONTAINER put_dns_fqdn $CONTAINER_IPS
        fi
    done
}

######################################################################
# IP Allocation Management helpers
######################################################################

# Claim addresses for a container in IPAM.  Expects to be called from
# with_container_addresses.
ipam_claim() {
    for CIDR in $3 ; do
        # NB: CONTAINER_IP is the IP of the weave container; it is set by wait_for_status.
        http_call_ip $CONTAINER_IP $HTTP_PORT PUT /ip/$1/${CIDR%/*}
    done
}

# Call IPAM as necessary to allocate addresses
# $1 is the full container id and following args are previously parsed CIDR_ARGS.
# Returns ALL_CIDRS and IPAM_CIDRS
ipam_cidrs() {
    CONTAINER_ID="$1"
    shift 1
    ALL_CIDRS=""
    IPAM_CIDRs=""
    if [ $# -eq 0 ] ; then
        # If no addresses passed in, get one in the default subnet
        if ! IPAM_CIDRS=$(call_weave POST /ip/$CONTAINER_ID) ; then
            return 1
        fi
        if [ "$IPAM_CIDRS" = "404 page not found" ] ; then
            echo "No IP address supplied (use the -iprange option on 'weave launch' to enable IP address allocation)" >&2
            return 1
        fi
        ALL_CIDRS="$IPAM_CIDRS"
    fi
    while [ $# -gt 0 ] ; do
        if [ "${1%:*}" = "net" ] ; then
            if [ "$1" = "net:default" ] ; then
                IPAM_URL=/ip/$CONTAINER_ID
            else
                IPAM_URL=/ip/$CONTAINER_ID/"${1#net:}"
            fi
            if ! CIDR=$(call_weave POST $IPAM_URL) ; then
                return 1
            fi
            if [ "$CIDR" = "404 page not found" ] ; then
                echo "IP address allocation must be enabled to use --subnet (use the -iprange option on 'weave launch')" >&2
                return 1
            fi
            if ! is_cidr "$CIDR" ; then
                echo "$CIDR" >&2
                return 1
            fi
            IPAM_CIDRS="$IPAM_CIDRS $CIDR"
            ALL_CIDRS="$ALL_CIDRS $CIDR"
        else
            ALL_CIDRS="$ALL_CIDRS $1"
        fi
        shift 1
    done
}

ipam_cidrs_or_die() {
    if ! ipam_cidrs "$@" ; then
        docker kill $1 >/dev/null 2>&1 || true
        exit 1
    fi
}

######################################################################
# weave proxy helpers
######################################################################


# TODO: Handle relative paths for args
# TODO: Handle args with spaces
tls_arg() {
    filename=${3:-$2}
    PROXY_VOLUMES="$PROXY_VOLUMES -v $1:/home/weave/tls/$filename.pem"
    PROXY_ARGS="$PROXY_ARGS --tls$2 /home/weave/tls/$filename.pem"
}

proxy_args() {
    PROXY_VOLUMES=""
    PROXY_ARGS=""
    while [ $# -gt 0 ]; do
        case "$1" in
          --tlscacert)
            shift
            tls_arg "$1" cacert ca
            ;;
          --tlscacert=*)
            tls_arg "${1#*=}" cacert ca
            ;;
          --tlscert)
            shift
            tls_arg "$1" cert
            ;;
          --tlscert=*)
            tls_arg "${1#*=}" cert
            ;;
          --tlskey)
            shift
            tls_arg "$1" key
            ;;
          --tlskey=*)
            tls_arg "${1#*=}" key
            ;;
          *)
            PROXY_ARGS="$PROXY_ARGS $1"
            ;;
        esac
        shift
    done
}

proxy_addr() {
    if addr=$(docker logs weaveproxy | head -n3 | grep -oE "proxy listening on .*"); then
      addr=${addr##* }
      host=${addr%:*}
      [ "$host" = "0.0.0.0" ] && host=$PROXY_HOST
      port=${addr#*:}
      echo "${1}tcp://${host:-$PROXY_HOST}:${port:-$PROXY_PORT}"
      return 0
    fi
    echo  "$PROXY_CONTAINER_NAME container is not present. Have you launched it?" >&2
    return 1
}

##########################################################################################

[ $(id -u) = 0 ] || {
    echo "weave must be run as 'root' when run locally" >&2
    exit 1
}

uname -s -r | sed -n -e 's|^\([^ ]*\) \([0-9][0-9]*\)\.\([0-9][0-9]*\).*|\1 \2 \3|p' | {
    if ! read sys maj min ; then
        echo "ERROR: Unable to parse operating system version $(uname -s -r)" >&2
        exit 1
    fi

    if [ "$sys" != 'Linux' ] ; then
        echo "ERROR: Operating systems other than Linux are not supported (you have $(uname -s -r))" >&2
        exit 1
    fi

    if ! [ \( "$maj" -eq 3 -a "$min" -ge 8 \) -o "$maj" -gt 3 ] ; then
        echo "WARNING: Linux kernel version 3.8 or newer is required (you have ${maj}.${min})" >&2
    fi
}

if ! command_exists ip ; then
    echo "ERROR: ip utility is missing. Please install it." >&2
    exit 1
fi

if ! ip netns list >/dev/null 2>&1 ; then
    echo "ERROR: $(ip -V) does not support network namespaces." >&2
    echo "       Please install iproute2-ss111010 or later." >&2
    exit 1
fi

if ! command_exists nsenter ; then
    echo "ERROR: nsenter utility missing. Please install it." >&2
    exit 1
fi

check_docker_version
DOCKER_VERSION_MAJOR=$(echo "$DOCKER_VERSION" | cut -d. -f 1)
DOCKER_VERSION_MINOR=$(echo "$DOCKER_VERSION" | cut -d. -f 2)
DOCKER_VERSION_PATCH=$(echo "$DOCKER_VERSION" | cut -d. -f 3)

[ $# -gt 0 ] || usage
COMMAND=$1
shift 1

case "$COMMAND" in
    setup)
        for img in $IMAGE $DNS_IMAGE $EXEC_IMAGE ; do
            docker pull $img
        done
        ;;
    # intentionally undocumented since it assumes knowledge of weave
    # internals
    create-bridge)
        create_bridge --without-ethtool
        ;;
    launch)
        check_not_running $CONTAINER_NAME $BASE_IMAGE
        create_bridge
        # We set the router name to the bridge mac since that is
        # stable across re-creations of the containers.
        #
        # TODO use the mac of one of the physical host interfaces
        # (eth0, wlan0, etc) so the name becomes stable across host
        # restarts.
        PEERNAME=$(cat /sys/class/net/$BRIDGE/address)
        # backward compatibility...
        if is_cidr "$1" ; then
            echo "WARNING: $1 parameter ignored; 'weave launch' no longer takes a CIDR as the first parameter" >&2
            shift 1
        fi
        CONTAINER_PORT=$PORT
        ARGS=""
        IPRANGE=
        IPRANGE_SPECIFIED=
        while [ $# -gt 0 ] ; do
            case "$1" in
                -password)
                    [ $# -gt 1 ] || usage
                    WEAVE_PASSWORD="$2"
                    export WEAVE_PASSWORD
                    shift 2
                    ;;
                -port)
                    [ $# -gt 1 ] || usage
                    CONTAINER_PORT="$2"
                    shift 2
                    ;;
                -iprange)
                    [ $# -gt 1 ] || usage
                    IPRANGE="$2"
                    IPRANGE_SPECIFIED=1
                    shift 2
                    ;;
                *)
                    ARGS="$ARGS '$(echo "$1" | sed "s|'|'\"'\"'|g")'"
                    shift
                    ;;
            esac
        done
        eval "set -- $ARGS"
        if [ -z "$IPRANGE_SPECIFIED" ] ; then
            IPRANGE="10.128.0.0/10"
            if command_exists netcheck && ! netcheck $IPRANGE ; then
                echo "Default -iprange $IPRANGE overlaps with existing route." >&2
                echo "Please pick another range and set it on all hosts." >&2
                exit 1
            fi
        fi
        # Set WEAVE_DOCKER_ARGS in the environment in order to supply
        # additional parameters, such as resource limits, to docker
        # when launching the weave container.
        CONTAINER=$(docker run --privileged -d --name=$CONTAINER_NAME \
            -p $PORT:$CONTAINER_PORT/tcp -p $PORT:$CONTAINER_PORT/udp \
            -v /var/run/docker.sock:/var/run/docker.sock \
            -e WEAVE_PASSWORD \
            $WEAVE_DOCKER_ARGS $IMAGE -iface $CONTAINER_IFNAME -port $CONTAINER_PORT -name "$PEERNAME" -nickname "$(hostname)" -iprange "$IPRANGE" "$@")
        with_container_netns_or_die $CONTAINER launch
        wait_for_status $CONTAINER_NAME $HTTP_PORT
        if [ -n "$IPRANGE" ] ; then
            # Tell the newly-started weave IP allocator about existing weave IPs
            with_container_addresses ipam_claim weave:expose $(docker ps -q --no-trunc)
        fi
        echo $CONTAINER
        ;;
    launch-dns)
        collect_cidr_args "$@"
        [ $CIDR_ARG_COUNT -lt 2 ] || usage
        shift $CIDR_ARG_COUNT
        check_not_running $DNS_CONTAINER_NAME $BASE_DNS_IMAGE
        create_bridge
        docker_bridge_ip
        # Set WEAVEDNS_DOCKER_ARGS in the environment in order to supply
        # additional parameters, such as resource limits, to docker
        # when launching the weave container.
        DNS_CONTAINER=$(docker run --privileged -d --name=$DNS_CONTAINER_NAME \
            -p $DOCKER_BRIDGE_IP:53:53/udp \
            -v /var/run/docker.sock:/var/run/docker.sock \
            $WEAVEDNS_DOCKER_ARGS $DNS_IMAGE -iface $CONTAINER_IFNAME -httpiface "$DNS_HTTP_IFNAME" "$@")
        ipam_cidrs_or_die $DNS_CONTAINER $CIDR_ARGS
        with_container_netns_or_die $DNS_CONTAINER attach $ALL_CIDRS
        populate_dns
        echo $DNS_CONTAINER
        ;;
    launch-proxy)
        check_not_running $PROXY_CONTAINER_NAME $EXEC_IMAGE
        # Set WEAVEPROXY_DOCKER_ARGS in the environment in order to supply
        # additional parameters, such as resource limits, to docker
        # when launching the weaveproxy container.
        proxy_args "$@"
        PROXY_CONTAINER=$(docker run --privileged -d --name=$PROXY_CONTAINER_NAME --net=host \
            $PROXY_VOLUMES \
            -v /var/run/docker.sock:/var/run/docker.sock \
            -v /proc:/hostproc \
            -e PROCFS=/hostproc \
            --entrypoint=/home/weave/weaveproxy \
            $WEAVEPROXY_DOCKER_ARGS $EXEC_IMAGE $PROXY_ARGS)
        wait_for_log $PROXY_CONTAINER_NAME "proxy listening"
        echo $PROXY_CONTAINER
        ;;
    proxy-env)
        proxy_addr "export DOCKER_HOST="
        ;;
    proxy-config)
        proxy_addr "-H="
        ;;
    connect)
        [ $# -gt 0 ] || usage
        if [ "$1" == "--replace" ]; then
          replace="-d replace=true"
          shift
        fi
        call_weave POST /connect $replace -d $(peer_args "$@")
        ;;
    forget)
        [ $# -gt 0 ] || usage
        call_weave POST /forget -d $(peer_args "$@")
        ;;
    status)
        res=0
        call_weave GET /status || res=1
        echo
        call_dns GET /status 2>/dev/null || true
        if check_running $PROXY_CONTAINER_NAME 2>/dev/null ; then
            echo
            echo "weave proxy is running"
        fi
        [ $res -eq 0 ]
        ;;
    ps)
        [ $# -eq 0 ] && CONTAINERS="weave:expose $(docker ps -q)" || CONTAINERS="$@"
        with_container_addresses echo_addresses $CONTAINERS
        ;;
    version)
        [ $# -eq 0 ] || usage
        echo weave script $SCRIPT_VERSION
        ask_version $CONTAINER_NAME $IMAGE || true
        ask_version $DNS_CONTAINER_NAME $DNS_IMAGE || true
        if ! EXEC_IMAGE_ID=$(docker inspect --format='{{.Id}}' $EXEC_IMAGE 2>/dev/null) ; then
            echo "Unable to find $EXEC_IMAGE image." >&2
        else
            EXEC_VERSION=$(docker images --no-trunc | grep $EXEC_IMAGE_ID | grep -v latest | tr -s ' ' | cut -d ' ' -f 2 | tr "\n" ' ')
            if [ -n "$EXEC_VERSION" ] ; then
                echo "weave exec $EXEC_VERSION"
            else
                echo "weave exec (unreleased version)"
            fi
        fi
        ;;
    run)
        dns_args "$@"
        shift $(dns_arg_count "$@")
        collect_cidr_args "$@"
        shift $CIDR_ARG_COUNT
        CONTAINER=$(docker run $DNS_ARGS -d "$@")
        create_bridge
        ipam_cidrs_or_die $CONTAINER $CIDR_ARGS
        with_container_netns_or_die $CONTAINER attach $ALL_CIDRS
        when_dns_running with_container_fqdn $CONTAINER put_dns_fqdn $ALL_CIDRS
        echo $CONTAINER
        ;;
    dns-args)
        dns_args "$@"
        echo -n $DNS_ARGS
        ;;
    docker-bridge-ip)
        docker_bridge_ip
        echo -n $DOCKER_BRIDGE_IP
        ;;
    start)
        collect_cidr_args "$@"
        shift $CIDR_ARG_COUNT
        [ $# -eq 1 ] || usage
        RES=$(docker start $1)
        CONTAINER=$(container_id $1)
        create_bridge
        ipam_cidrs_or_die $CONTAINER $CIDR_ARGS
        with_container_netns_or_die $CONTAINER attach $ALL_CIDRS
        when_dns_running with_container_fqdn $CONTAINER put_dns_fqdn $ALL_CIDRS
        echo $RES
        ;;
    attach)
        collect_cidr_args "$@"
        shift $CIDR_ARG_COUNT
        if [ "$1" = "--or-die" ]; then
          ATTACH_TYPE="_or_die"
          shift
        fi
        [ $# -eq 1 ] || usage
        CONTAINER=$(container_id $1)
        create_bridge
        ipam_cidrs$ATTACH_TYPE $CONTAINER $CIDR_ARGS
        with_container_netns$ATTACH_TYPE $CONTAINER attach $ALL_CIDRS >/dev/null
        when_dns_running with_container_fqdn $CONTAINER put_dns_fqdn $ALL_CIDRS
        ;;
    detach)
        collect_cidr_args "$@"
        shift $CIDR_ARG_COUNT
        [ $# -eq 1 ] || usage
        CONTAINER=$(container_id $1)
        ipam_cidrs $CONTAINER $CIDR_ARGS
        with_container_netns $CONTAINER detach $ALL_CIDRS >/dev/null
        when_dns_running with_container_fqdn $CONTAINER delete_dns_fqdn $ALL_CIDRS
        for CIDR in $IPAM_CIDRS ; do
            call_weave DELETE /ip/$CONTAINER/${CIDR%/*}
        done
        ;;
    dns-add)
        collect_ip_args "$@"
        shift $IP_COUNT
        [ $IP_COUNT -gt 0 -a \( $# -eq 1 -o \( $# -eq 3 -a "$2" = "-h" \) \) ] || usage
        check_running $DNS_CONTAINER_NAME
        CONTAINER=$(container_id $1)
        if [ $# -eq 1 ] ; then
            with_container_fqdn $CONTAINER put_dns_fqdn $IP_ARGS
        else
            put_dns_fqdn $CONTAINER "$3" $IP_ARGS
        fi
        ;;
    dns-remove)
        collect_ip_args "$@"
        shift $IP_COUNT
        [ $IP_COUNT -gt 0 -a \( $# -eq 1 -o \( $# -eq 3 -a "$2" = "-h" \) \) ] || usage
        check_running $DNS_CONTAINER_NAME
        CONTAINER=$(container_id $1)
        if [ $# -eq 1 ] ; then
            delete_dns $CONTAINER $IP_ARGS
        else
            delete_dns_fqdn $CONTAINER "$3" $IP_ARGS
        fi
        ;;
    expose)
        collect_cidr_args "$@"
        shift $CIDR_ARG_COUNT
        ipam_cidrs weave:expose $CIDR_ARGS
        if [ $# -eq 0 ] ; then
            FQDN=""
        else
            [ $# -eq 2 -a "$1" = "-h" ] || usage
            FQDN="$2"
        fi
        create_bridge --without-ethtool
        for CIDR in $ALL_CIDRS ; do
            if ! ip addr show dev $BRIDGE | grep -qF $CIDR ; then
                ip addr add dev $BRIDGE $CIDR
                arp_update $BRIDGE $CIDR
                add_iptables_rule nat WEAVE -d $CIDR ! -s $CIDR -j MASQUERADE
                add_iptables_rule nat WEAVE -s $CIDR ! -d $CIDR -j MASQUERADE
                if [ -n "$FQDN" ] ; then
                    when_dns_running put_dns_fqdn 'weave:expose' $FQDN $CIDR
                fi
            fi
        done
        ;;
    hide)
        collect_cidr_args "$@"
        shift $CIDR_ARG_COUNT
        ipam_cidrs weave:expose $CIDR_ARGS
        create_bridge --without-ethtool
        for CIDR in $ALL_CIDRS ; do
            if ip addr show dev $BRIDGE | grep -qF $CIDR ; then
                ip addr del dev $BRIDGE $CIDR
                delete_iptables_rule nat WEAVE -d $CIDR ! -s $CIDR -j MASQUERADE
                delete_iptables_rule nat WEAVE -s $CIDR ! -d $CIDR -j MASQUERADE
                when_dns_running delete_dns 'weave:expose' $CIDR
            fi
        done
        for CIDR in $IPAM_CIDRS ; do
            call_weave DELETE /ip/weave:expose/${CIDR%/*}
        done
        ;;
    stop)
        [ $# -eq 0 ] || usage
        stop $CONTAINER_NAME "Weave"
        conntrack -D -p udp --dport $PORT >/dev/null 2>&1 || true
        ;;
    stop-dns)
        [ $# -eq 0 ] || usage
        stop $DNS_CONTAINER_NAME "WeaveDNS"
        ;;
    stop-proxy)
        [ $# -eq 0 ] || usage
        stop $PROXY_CONTAINER_NAME "Proxy"
        ;;
    reset)
        [ $# -eq 0 ] || usage
        call_weave DELETE /peer >/dev/null 2>&1 || true
        for NAME in $CONTAINER_NAME $DNS_CONTAINER_NAME $PROXY_CONTAINER_NAME ; do
            docker stop  $NAME >/dev/null 2>&1 || true
            docker rm -f $NAME >/dev/null 2>&1 || true
        done
        conntrack -D -p udp --dport $PORT >/dev/null 2>&1 || true
        destroy_bridge
        for LOCAL_IFNAME in $(ip link show | grep v${CONTAINER_IFNAME}pl | cut -d ' ' -f 2 | tr -d ':') ; do
            ip link del $LOCAL_IFNAME
        done
        ;;
    rmpeer)
        [ $# -eq 1 ] || usage
        PEER=$1
        call_weave DELETE /peer/$PEER
        ;;
    *)
        echo "Unknown weave command '$COMMAND'" >&2
        usage
        ;;
esac