From a75a0d870947f3b7d207e01edf6e78d920f492e3 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Thu, 18 Sep 2014 11:24:08 +0100
Subject: [PATCH] If and only if network setup because the container died, say
 so. This involves capturing stderr output from all the 'ip' commands so we
 can hide that output if we see the process died, or show it to the user if
 the process didn't die, in which case we don't know why we failed.

---
 weaver/weave | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/weaver/weave b/weaver/weave
index 7aa4d14d..8da45d72 100755
--- a/weaver/weave
+++ b/weaver/weave
@@ -120,15 +120,16 @@ configure_container_networking() {
     EXITCODE=1
     LOCAL_IFNAME="v${CONTAINER_IFNAME}pl${NSPID}"
     GUEST_IFNAME="v${CONTAINER_IFNAME}pg${NSPID}"
-    if ip link add name $LOCAL_IFNAME mtu $MTU type veth peer name $GUEST_IFNAME mtu $MTU ; then
-        if  ip link set $LOCAL_IFNAME master $BRIDGE && \
-            ip link set $LOCAL_IFNAME up && \
-            ip link set $GUEST_IFNAME netns $NSPID
+    IP_TMPFILE=/tmp/weave_ip_output_$$
+    if ip link add name $LOCAL_IFNAME mtu $MTU type veth peer name $GUEST_IFNAME mtu $MTU > $IP_TMPFILE 2>&1 ; then
+        if  (ip link set $LOCAL_IFNAME master $BRIDGE &&
+            ip link set $LOCAL_IFNAME up &&
+            ip link set $GUEST_IFNAME netns $NSPID) > $IP_TMPFILE 2>&1
         then
-            ip netns exec $NSPID ip link set $GUEST_IFNAME name $CONTAINER_IFNAME && \
-            ip netns exec $NSPID ip addr add $2 dev $CONTAINER_IFNAME && \
-            ip netns exec $NSPID ip link set $CONTAINER_IFNAME up && \
-            (check_command_and_run ethtool ip netns exec $NSPID ethtool -K $3 tx off >/dev/null) && \
+            (ip netns exec $NSPID ip link set $GUEST_IFNAME name $CONTAINER_IFNAME &&
+            ip netns exec $NSPID ip addr add $2 dev $CONTAINER_IFNAME &&
+            ip netns exec $NSPID ip link set $CONTAINER_IFNAME up &&
+            check_command_and_run ethtool ip netns exec $NSPID ethtool -K $3 tx off) > $IP_TMPFILE 2>&1 &&
             EXITCODE=0
         else
             # failed before we assigned the veth to the container's namespace - delete it
@@ -136,6 +137,16 @@ configure_container_networking() {
         fi
     fi
 
+    if [ "$EXITCODE" -ne 0 ] ; then
+        if ! ps -p $DOCKERPID > /dev/null 2>&1 ; then
+            echo "Container died during network set-up. ID $1" >&2
+        else
+            echo "Failure during network set-up:" >&2
+            cat $IP_TMPFILE
+        fi
+    fi
+
+    rm -f $IP_TMPFILE
     rm -f /var/run/netns/$NSPID
 
     return $EXITCODE