introduce WEAVEDNS_DOCKER_ARGS

same purpuse as WEAVE_DOCKER_ARGS, except for weavedns
This allows us to get rid if the -fallback option since
WEAVEDNS_DOCKER_ARGS="--dns=..." has the same effect.

Closes #487.

weave

@@ -57,6 +57,7 @@ exec_remote() {
         -v "$PROCFS":/hostproc \
         -e VERSION \
         -e WEAVE_DOCKER_ARGS \
+        -e WEAVEDNS_DOCKER_ARGS \
         -e WEAVE_PASSWORD \
         -e DOCKER_BRIDGE \
         -e PROCFS=/hostproc --privileged --net=host \
@@ -587,9 +588,12 @@ case "$COMMAND" in
         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 \
-            $DNS_IMAGE -iface $CONTAINER_IFNAME "$@")
+            $WEAVEDNS_DOCKER_ARGS $DNS_IMAGE -iface $CONTAINER_IFNAME "$@")
         with_container_netns $DNS_CONTAINER attach $CIDR >/dev/null
         populate_dns
         echo $DNS_CONTAINER

weavedns/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"github.com/miekg/dns"
 	. "github.com/zettio/weave/common"
 	weavedns "github.com/zettio/weave/nameserver"
 	weavenet "github.com/zettio/weave/net"
@@ -23,7 +22,6 @@ func main() {
 		ifaceName   string
 		apiPath     string
 		localDomain string
-		fallback    string
 		dnsPort     int
 		httpPort    int
 		wait        int
@@ -42,7 +40,6 @@ func main() {
 	flag.IntVar(&wait, "wait", 0, "number of seconds to wait for interface to be created and come up")
 	flag.IntVar(&dnsPort, "dnsport", weavedns.DefaultServerPort, "port to listen to DNS requests")
 	flag.IntVar(&httpPort, "httpport", 6785, "port to listen to HTTP requests")
-	flag.StringVar(&fallback, "fallback", "", "force a fallback (ie, '8.8.8.8:53') instead of /etc/resolv.conf values")
 	flag.IntVar(&timeout, "timeout", weavedns.DefaultTimeout, "timeout for resolutions")
 	flag.IntVar(&udpbuf, "udpbuf", weavedns.DefaultUDPBuflen, "UDP buffer length")
 	flag.IntVar(&cacheLen, "cache", weavedns.DefaultCacheLen, "cache length")
@@ -86,15 +83,6 @@ func main() {
 		UDPBufLen:   udpbuf,
 	}
 
-	if len(fallback) > 0 {
-		fallbackHost, fallbackPort, err := net.SplitHostPort(fallback)
-		if err != nil {
-			Error.Fatal("Could not parse fallback host and port", err)
-		}
-		srvConfig.UpstreamCfg = &dns.ClientConfig{Servers: []string{fallbackHost}, Port: fallbackPort}
-		Debug.Printf("DNS fallback at %s:%s", fallbackHost, fallbackPort)
-	}
-
 	srv, err := weavedns.NewDNSServer(srvConfig, zone, iface)
 	if err != nil {
 		Error.Fatal("Failed to initialize the WeaveDNS server", err)