weave/weave

#!/bin/sh
set -e

usage() {
    echo "Usage:"
    echo "weave launch     [-password <password> | -passwordfile <path>] <peer> ..."
    echo "weave launch-dns <cidr>"
    echo "weave connect    <peer>"
    echo "weave run        [--with-dns] <cidr> <docker run args> ..."
    echo "weave start      <cidr> <container_id>"
    echo "weave attach     <cidr> <container_id>"
    echo "weave detach     <cidr> <container_id>"
    echo "weave expose     <cidr>"
    echo "weave hide       <cidr>"
    echo "weave ps"
    echo "weave status"
    echo "weave version"
    echo "weave stop"
    echo "weave stop-dns"
    echo "weave reset"
    echo
    echo "where <peer> is of the form <ip_address_or_fqdn>[:<port>], and"
    echo "      <cidr> is of the form <ip_address>/<routing_prefix_length>"
    exit 1
}

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

[ $# -gt 0 ] || usage

IMAGE=zettio/weave
DNS_IMAGE=zettio/weavedns
CONTAINER_NAME=weave
DNS_CONTAINER_NAME=weavedns
BRIDGE=weave
CONTAINER_IFNAME=ethwe
MTU=65535
PORT=6783
HTTP_PORT=6784
DNS_HTTP_PORT=6785
DOCKER_BRIDGE=${DOCKER_BRIDGE:-docker0}

COMMAND=$1

shift 1

# 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
}

command_exists_or_warn () {
    if ! command_exists $1 ; then
        echo "Cannot find $1; please install it. Continuing without it." >&2
        return 1
    fi
}

is_cidr() {
    # The regexp here is far from precise, but good enough.
    echo "$1" | grep -E '^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}/[0-9]{1,2}$' >/dev/null
}

validate_cidr() {
    if ! is_cidr "$1" ; then
        echo "Invalid CIDR: $1" >&2
        echo "CIDR must of be of form <ip_address>/<routing_prefix_length>, e.g. 10.0.1.1/24" >&2
        exit 1
    fi
}

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
}

create_bridge() {
    [ ! -d /sys/class/net/$BRIDGE ] && {
        ip link add name $BRIDGE type bridge
        ip link set dev $BRIDGE address 7a:$(od -txC -An -N5 /dev/urandom | tr \  : | tail -c+2)
        # 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
        # disable offloading
        if command_exists_or_warn ethtool; then ethtool -K $BRIDGE tx off >/dev/null; 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
    }
    ip link set dev $BRIDGE up
}

destroy_bridge() {
    if [ -d /sys/class/net/$BRIDGE ] ; then
        ip link del dev $BRIDGE
    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 $NETNS to the network namespace 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

    NETNS=$CONTAINER_PID
    [ ! -d /var/run/netns ] && mkdir -p /var/run/netns
    rm -f /var/run/netns/$NETNS
    ln -s /proc/$CONTAINER_PID/ns/net /var/run/netns/$NETNS

    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>$IP_TMPERR ; then
        STATUS=1
        if [ "$(docker inspect --format='{{ .State.Pid }}' $CONTAINER)" != "$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 $IP_TMPERR /var/run/netns/$NETNS
    return $STATUS
}

connect_container_to_bridge() {
    if [ "$(readlink /proc/$CONTAINER_PID/ns/net)" = "$(readlink /proc/$$/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
    if ! ip link add name $LOCAL_IFNAME mtu $MTU type veth peer name $GUEST_IFNAME mtu $MTU ; then
        return 1
    fi

    if { if command_exists_or_warn ethtool; then ethtool -K $GUEST_IFNAME tx off >/dev/null; fi } &&
        ip link set $LOCAL_IFNAME master $BRIDGE &&
        ip link set $LOCAL_IFNAME up &&
        ip link set $GUEST_IFNAME netns $NETNS ; then
        ip netns exec $NETNS ip link set $GUEST_IFNAME name $CONTAINER_IFNAME
    else
        # failed before we assigned the veth to the container's
        # namespace - delete it
        ip link del $LOCAL_IFNAME type veth || true
        return 1
    fi
}

launch() {
    if ! ip netns exec $NETNS 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 &&
        { if command_exists_or_warn ethtool ; then ip netns exec $NETNS ethtool -K eth0 tx off >/dev/null; fi } &&
        ip netns exec $NETNS ip link set $CONTAINER_IFNAME up
}

attach() {
    if ip link show $LOCAL_IFNAME >/dev/null 2>&1 ; then
        # veth name already exists, so assume we set it up already;
        # just add the IP address.
        if ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME | grep -F $1 >/dev/null ; then
            # address was there already
            return 0
        fi

        if ! ip netns exec $NETNS ip addr add $1 dev $CONTAINER_IFNAME ; then
            return 1
        fi

        return 0
    fi

    if ! connect_container_to_bridge ||
        ! ip netns exec $NETNS ip addr add $1 dev $CONTAINER_IFNAME ||
        ! ip netns exec $NETNS ip link set $CONTAINER_IFNAME up ; then
        return 1
    fi

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

detach() {
    if ! ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME | grep -F $1 >/dev/null ; then
        # address is not there, leave the device alone
        return 0
    fi

    if ! ip netns exec $NETNS ip addr del $1 dev $CONTAINER_IFNAME ; then
        return 1
    fi

    if [ -n "$(ip netns exec $NETNS 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
    ip link del $LOCAL_IFNAME type veth
}

# Call url $4 with http verb $3 on container $1 at port $2
http_call() {
    if ! status=$(docker inspect --format='{{ .State.Running }} {{ .NetworkSettings.IPAddress }}' $1 2>/dev/null); then
        echo "$1 container is not present; have you launched it?" >&2
        exit 1
    fi
    case "$status" in
        "true ")
            echo "$1 container has no IP address; is Docker networking enabled?" >&2
            exit 1
            ;;
        true*)
            ip="${status#true }"
            ;;
        *)
            echo "$1 container is not running." >&2
            exit 1
            ;;
    esac
    shift 1
    http_call_ip $ip "$@"
}

http_call_ip() {
    ip="$1"
    port="$2"
    http_verb="$3"
    url="$4"
    shift 4
    if command_exists curl ; then
        curl -s -X $http_verb "$@" http://$ip:$port$url
    else
        echo "Cannot find curl, which is required for this operation." >&2
        exit 1
    fi
}

# Perform operation $1 on container ID $2 to local DNS database at address $3
# This function is only called where we know $2 is a valid container name
tell_dns() {
    if ! DNSID=$(docker inspect --format='{{ .Id }}' $DNS_CONTAINER_NAME 2>/dev/null) || [ -z "$DNSID" ] ; then
        # weavedns not running - silently return
        return
    fi
    # get the long form of the container ID
    CONTAINER=$(docker inspect --format '{{.Id}}' $2 2>/dev/null)
    # extract IP address and routing prefix from CIDR
    WEAVE_ADDR_IP=$(echo $3 | sed -e 's/\([^/]*\)\/\(.*\)/\1/')
    MORE_ARGS=$(docker inspect --format '--data-urlencode fqdn={{ .Config.Hostname }}.{{ .Config.Domainname }}.' $CONTAINER 2>/dev/null) && true
    http_call $DNS_CONTAINER_NAME $DNS_HTTP_PORT $1 /name/$CONTAINER/$WEAVE_ADDR_IP $MORE_ARGS
}

# Tell the newly-started weaveDNS about existing weave IPs
populate_dns() {
    DNS_IP=$(docker inspect --format '{{ .NetworkSettings.IPAddress }}' $DNS_CONTAINER_NAME)
    WAIT_TIME=1
    while ! http_call_ip $DNS_IP $DNS_HTTP_PORT GET /status >/dev/null && [ $WAIT_TIME -lt 4 ]; do
        sleep $WAIT_TIME
        WAIT_TIME=$((WAIT_TIME+1))
    done
    if [ $WAIT_TIME = 4 ]; then
        echo "Timed out waiting for weaveDNS container to start." >&2
        echo "If running, it will not be pre-populated." >&2
    fi

    for CONTAINER in $(docker ps -q --no-trunc); do
        MORE_ARGS=$(docker inspect --format '--data-urlencode fqdn={{ .Config.Hostname }}.{{ .Config.Domainname }}.' $CONTAINER 2>/dev/null) && true
        if CONTAINER_ADDRS=$(with_container_netns $CONTAINER container_weave_addrs 2>&1) ; then
            CONTAINER_IPS=$(echo "$CONTAINER_ADDRS" | grep -o 'inet .*' | sed -e 's/inet \([^/]*\)\/\(.*\)/\1/')
            for IP in $CONTAINER_IPS; do
                http_call_ip $DNS_IP $DNS_HTTP_PORT PUT /name/$CONTAINER/$IP $MORE_ARGS
            done
        fi
    done
}

# 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
            ;;
        "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
}

container_weave_addrs() {
    ip netns exec $NETNS ip addr show dev $CONTAINER_IFNAME
}

uname -s -r | sed -n 's|^\([^ ]*\) \([0-9]\+\)\.\([0-9]\+\).*|\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 ! [ \( "$maj" -eq 3 -a "$min" -ge 5 \) -o "$maj" -gt 3 ] ; then
        echo "WARNING: Linux kernel version 3.5 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 ! DOCKER_VERSION=$(docker -v | sed -n 's|^Docker version \([0-9]\+\.[0-9]\+.[0-9]\+\).*|\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

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)

case "$COMMAND" in
    launch)
        check_not_running $CONTAINER_NAME $IMAGE
        create_bridge
        # We set the router name to the bridge mac since that is
        # stable across re-creations of the containers.
        #
        # TODO use the mac of one of the physical host interfaces
        # (eth0, wlan0, etc) so the name becomes stable across host
        # restarts.
        MACADDR=$(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
        if [ "$1" = "-password" ] ; then
            [ $# -gt 1 ] || usage
            PASSWORD=$2
            shift 2
        elif [ "$1" = "-passwordfile" ] ; then
            [ $# -gt 1 ] || usage
            PASSWORDFILE=$2
            shift 2
        fi
        # Set WEAVE_DOCKER_ARGS in the environment in order to supply
        # additional parameters, such as resource limits, to docker
        # when launching the weave container.
        CONTAINER=$(docker run --privileged -d --name=$CONTAINER_NAME \
            -p $PORT:$PORT/tcp -p $PORT:$PORT/udp \
            ${PASSWORD:+-e WEAVE_PASSWORD="$PASSWORD"} ${PASSWORDFILE:+--env-file="$PASSWORDFILE"} \
            $WEAVE_DOCKER_ARGS $IMAGE -name $MACADDR -iface $CONTAINER_IFNAME "$@")
        with_container_netns $CONTAINER launch >/dev/null
        echo $CONTAINER
        ;;
    launch-dns)
        [ $# -gt 0 ] || usage
        CIDR=$1
        shift 1
        check_not_running $DNS_CONTAINER_NAME $DNS_IMAGE
        create_bridge
        docker_bridge_ip
        DNS_CONTAINER=$(docker run --privileged -d --name=$DNS_CONTAINER_NAME \
            -p $DOCKER_BRIDGE_IP:53:53/udp -v /var/run/docker.sock:/var/run/docker.sock \
            $DNS_IMAGE -iface $CONTAINER_IFNAME "$@")
        with_container_netns $DNS_CONTAINER attach $CIDR >/dev/null
        populate_dns
        echo $DNS_CONTAINER
        ;;
    connect)
        [ $# -eq 1 ] || usage
        http_call $CONTAINER_NAME $HTTP_PORT POST /connect -d "peer=$1"
        ;;
    status)
        http_call $CONTAINER_NAME $HTTP_PORT GET /status
        ;;
    ps)
        [ $# -eq 0 ] || usage
        for CONTAINER_ID in $(docker ps -q) ; do
            if CONTAINER_ADDRS=$(with_container_netns $CONTAINER_ID container_weave_addrs 2>&1) ; then
                CONTAINER_MAC=$(echo "$CONTAINER_ADDRS" | grep -o 'link/ether .*' | cut -d ' ' -f 2)
                CONTAINER_IPS=$(echo "$CONTAINER_ADDRS" | grep -o 'inet .*'       | cut -d ' ' -f 2)
                echo $CONTAINER_ID $CONTAINER_MAC $CONTAINER_IPS
            fi
        done
        ;;
    version)
        [ $# -eq 0 ] || usage
        # Try the running container first; if no luck try the image
        if ! DOCKERIMAGE=$(docker inspect --format='{{ .Image }}' $CONTAINER_NAME 2>/dev/null) ; then
            if ! DOCKERIMAGE=$(docker inspect --format='{{ .Id }}' $IMAGE 2>/dev/null) ; then
                echo "Unable to find $IMAGE image." >&2
                exit 1
            fi
        fi
        docker images --no-trunc | grep $DOCKERIMAGE | grep -v latest | tr -s ' ' | cut -d ' ' -f 2
        ;;
    run)
        [ $# -gt 0 ] || usage
        if [ "$1" = "--with-dns" ] ; then
            shift 1
            if [ \( "$DOCKER_VERSION_MAJOR" -lt 1 \) -o \
                 \( "$DOCKER_VERSION_MAJOR" -eq 1 -a \
                    "$DOCKER_VERSION_MINOR" -lt 2 \) ] ; then
                echo "ERROR: The '--with-dns' option requires Docker 1.2.0 or later; you are running $DOCKER_VERSION" >&2
                exit 1
            fi
            docker_bridge_ip
            DNS_ARG="--dns $DOCKER_BRIDGE_IP"
            DNS_SEARCH_ARG="--dns-search=."
            for arg in "$@"; do
                case $arg in
                    --dns-search=*)
                        DNS_SEARCH_ARG=""
                        ;;
                    *)
                        ;;
                esac;
            done
        fi
        validate_cidr $1
        CIDR=$1
        shift 1
        create_bridge
        CONTAINER=$(docker run $DNS_ARG $DNS_SEARCH_ARG -d "$@")
        with_container_netns $CONTAINER attach $CIDR >/dev/null
        tell_dns PUT $CONTAINER $CIDR
        echo $CONTAINER
        ;;
    start)
        [ $# -eq 2 ] || usage
        validate_cidr $1
        create_bridge
        CONTAINER=$(docker start $2)
        with_container_netns $CONTAINER attach $1 >/dev/null
        tell_dns PUT $CONTAINER $1
        echo $CONTAINER
        ;;
    attach)
        [ $# -eq 2 ] || usage
        validate_cidr $1
        create_bridge
        with_container_netns $2 attach $1 >/dev/null
        tell_dns PUT $2 $1
        ;;
    detach)
        [ $# -eq 2 ] || usage
        validate_cidr $1
        with_container_netns $2 detach $1 >/dev/null
        tell_dns DELETE $2 $1
        ;;
    expose)
        [ $# -eq 1 ] || usage
        validate_cidr $1
        create_bridge
        if ! ip addr show dev $BRIDGE | grep -qF $1
        then
            ip addr add dev $BRIDGE $1
            add_iptables_rule nat WEAVE -o $BRIDGE ! -s $1 -j MASQUERADE
            add_iptables_rule nat WEAVE -s $1 ! -o $BRIDGE -j MASQUERADE
        fi
        ;;
    hide)
        [ $# -eq 1 ] || usage
        validate_cidr $1
        create_bridge
        if ip addr show dev $BRIDGE | grep -qF $1
        then
            ip addr del dev $BRIDGE $1
            delete_iptables_rule nat WEAVE -o $BRIDGE ! -s $1 -j MASQUERADE
            delete_iptables_rule nat WEAVE -s $1 ! -o $BRIDGE -j MASQUERADE
        fi
        ;;
    stop)
        [ $# -eq 0 ] || usage
        if ! docker kill $CONTAINER_NAME >/dev/null 2>&1 ; then
            echo "Weave is not running." >&2
        fi
        docker rm -f $CONTAINER_NAME >/dev/null 2>&1 || true
        if command_exists_or_warn conntrack; then
            conntrack -D -p udp --dport $PORT >/dev/null 2>&1 || true
        fi
        ;;
    stop-dns)
        [ $# -eq 0 ] || usage
        if ! docker kill $DNS_CONTAINER_NAME >/dev/null 2>&1 ; then
            echo "WeaveDNS is not running." >&2
        fi
        docker rm -f $DNS_CONTAINER_NAME >/dev/null 2>&1 || true
        ;;
    reset)
        [ $# -eq 0 ] || usage
        docker kill  $CONTAINER_NAME     >/dev/null 2>&1 || true
        docker kill  $DNS_CONTAINER_NAME >/dev/null 2>&1 || true
        docker rm -f $CONTAINER_NAME     >/dev/null 2>&1 || true
        docker rm -f $DNS_CONTAINER_NAME >/dev/null 2>&1 || true
        if command_exists_or_warn conntrack; then
            conntrack -D -p udp --dport $PORT >/dev/null 2>&1 || true
        fi
        destroy_bridge
        for LOCAL_IFNAME in $(ip link show | grep v${CONTAINER_IFNAME}pl | cut -d ' ' -f 2 | tr -d ':') ; do
            ip link del $LOCAL_IFNAME
        done
        ;;
    *)
        echo "Unknown weave command '$COMMAND'" >&2
        usage
        ;;
esac