Use fmt precision to limit string length

The previous code used string slices to limit the length of certain
fields like endpoint or sandbox IDs.  This assumes that these strings
are at least as long as the slice length.  Unfortunately, some sandbox
IDs can be smaller than 7 characters.   This fix addresses this issue
by systematically converting format string calls that were taking
fixed-slice arguments to use a precision specifier in the string format
itself.  From the golang fmt package documentation:

    For strings, byte slices and byte arrays, however, precision limits
    the length of the input to be formatted (not the size of the output),
    truncating if necessary. Normally it is measured in runes, but for
    these types when formatted with the %x or %X format it is measured
    in bytes.

This nicely fits the desired behavior: it will limit the number of
runes considered for string interpolation to the precision value.

Signed-off-by: Chris Telfer <ctelfer@docker.com>

1 files changed, 11 insertions, 11 deletions

diff --git a/libnetwork/service_linux.go b/libnetwork/service_linux.go
index 532b8c8233..3ffa60719c 100644
--- a/libnetwork/service_linux.go
+++ b/libnetwork/service_linux.go
@@ -43,7 +43,7 @@ func (sb *sandbox) populateLoadBalancers(ep *endpoint) {
 
 	if n.ingress {
 		if err := addRedirectRules(sb.Key(), eIP, ep.ingressPorts); err != nil {
-			logrus.Errorf("Failed to add redirect rules for ep %s (%s): %v", ep.Name(), ep.ID()[0:7], err)
+			logrus.Errorf("Failed to add redirect rules for ep %s (%.7s): %v", ep.Name(), ep.ID(), err)
 		}
 	}
 }
@@ -106,7 +106,7 @@ func (n *network) addLBBackend(ip net.IP, lb *loadBalancer) {
 
 	i, err := ipvs.New(sb.Key())
 	if err != nil {
-		logrus.Errorf("Failed to create an ipvs handle for sbox %s (%s,%s) for lb addition: %v", sb.ID()[0:7], sb.ContainerID()[0:7], sb.Key(), err)
+		logrus.Errorf("Failed to create an ipvs handle for sbox %.7s (%.7s,%s) for lb addition: %v", sb.ID(), sb.ContainerID(), sb.Key(), err)
 		return
 	}
 	defer i.Close()
@@ -142,14 +142,14 @@ func (n *network) addLBBackend(ip net.IP, lb *loadBalancer) {
 			}
 		}
 
-		logrus.Debugf("Creating service for vip %s fwMark %d ingressPorts %#v in sbox %s (%s)", lb.vip, lb.fwMark, lb.service.ingressPorts, sb.ID()[0:7], sb.ContainerID()[0:7])
+		logrus.Debugf("Creating service for vip %s fwMark %d ingressPorts %#v in sbox %.7s (%.7s)", lb.vip, lb.fwMark, lb.service.ingressPorts, sb.ID(), sb.ContainerID())
 		if err := invokeFWMarker(sb.Key(), lb.vip, lb.fwMark, lb.service.ingressPorts, eIP, false); err != nil {
-			logrus.Errorf("Failed to add firewall mark rule in sbox %s (%s): %v", sb.ID()[0:7], sb.ContainerID()[0:7], err)
+			logrus.Errorf("Failed to add firewall mark rule in sbox %.7s (%.7s): %v", sb.ID(), sb.ContainerID(), err)
 			return
 		}
 
 		if err := i.NewService(s); err != nil && err != syscall.EEXIST {
-			logrus.Errorf("Failed to create a new service for vip %s fwmark %d in sbox %s (%s): %v", lb.vip, lb.fwMark, sb.ID()[0:7], sb.ContainerID()[0:7], err)
+			logrus.Errorf("Failed to create a new service for vip %s fwmark %d in sbox %.7s (%.7s): %v", lb.vip, lb.fwMark, sb.ID(), sb.ContainerID(), err)
 			return
 		}
 	}
@@ -164,7 +164,7 @@ func (n *network) addLBBackend(ip net.IP, lb *loadBalancer) {
 	// destination.
 	s.SchedName = ""
 	if err := i.NewDestination(s, d); err != nil && err != syscall.EEXIST {
-		logrus.Errorf("Failed to create real server %s for vip %s fwmark %d in sbox %s (%s): %v", ip, lb.vip, lb.fwMark, sb.ID()[0:7], sb.ContainerID()[0:7], err)
+		logrus.Errorf("Failed to create real server %s for vip %s fwmark %d in sbox %.7s (%.7s): %v", ip, lb.vip, lb.fwMark, sb.ID(), sb.ContainerID(), err)
 	}
 }
 
@@ -189,7 +189,7 @@ func (n *network) rmLBBackend(ip net.IP, lb *loadBalancer, rmService bool, fullR
 
 	i, err := ipvs.New(sb.Key())
 	if err != nil {
-		logrus.Errorf("Failed to create an ipvs handle for sbox %s (%s,%s) for lb removal: %v", sb.ID()[0:7], sb.ContainerID()[0:7], sb.Key(), err)
+		logrus.Errorf("Failed to create an ipvs handle for sbox %.7s (%.7s,%s) for lb removal: %v", sb.ID(), sb.ContainerID(), sb.Key(), err)
 		return
 	}
 	defer i.Close()
@@ -207,19 +207,19 @@ func (n *network) rmLBBackend(ip net.IP, lb *loadBalancer, rmService bool, fullR
 
 	if fullRemove {
 		if err := i.DelDestination(s, d); err != nil && err != syscall.ENOENT {
-			logrus.Errorf("Failed to delete real server %s for vip %s fwmark %d in sbox %s (%s): %v", ip, lb.vip, lb.fwMark, sb.ID()[0:7], sb.ContainerID()[0:7], err)
+			logrus.Errorf("Failed to delete real server %s for vip %s fwmark %d in sbox %.7s (%.7s): %v", ip, lb.vip, lb.fwMark, sb.ID(), sb.ContainerID(), err)
 		}
 	} else {
 		d.Weight = 0
 		if err := i.UpdateDestination(s, d); err != nil && err != syscall.ENOENT {
-			logrus.Errorf("Failed to set LB weight of real server %s to 0 for vip %s fwmark %d in sbox %s (%s): %v", ip, lb.vip, lb.fwMark, sb.ID()[0:7], sb.ContainerID()[0:7], err)
+			logrus.Errorf("Failed to set LB weight of real server %s to 0 for vip %s fwmark %d in sbox %.7s (%.7s): %v", ip, lb.vip, lb.fwMark, sb.ID(), sb.ContainerID(), err)
 		}
 	}
 
 	if rmService {
 		s.SchedName = ipvs.RoundRobin
 		if err := i.DelService(s); err != nil && err != syscall.ENOENT {
-			logrus.Errorf("Failed to delete service for vip %s fwmark %d in sbox %s (%s): %v", lb.vip, lb.fwMark, sb.ID()[0:7], sb.ContainerID()[0:7], err)
+			logrus.Errorf("Failed to delete service for vip %s fwmark %d in sbox %.7s (%.7s): %v", lb.vip, lb.fwMark, sb.ID(), sb.ContainerID(), err)
 		}
 
 		if sb.ingress {
@@ -234,7 +234,7 @@ func (n *network) rmLBBackend(ip net.IP, lb *loadBalancer, rmService bool, fullR
 		}
 
 		if err := invokeFWMarker(sb.Key(), lb.vip, lb.fwMark, lb.service.ingressPorts, eIP, true); err != nil {
-			logrus.Errorf("Failed to delete firewall mark rule in sbox %s (%s): %v", sb.ID()[0:7], sb.ContainerID()[0:7], err)
+			logrus.Errorf("Failed to delete firewall mark rule in sbox %.7s (%.7s): %v", sb.ID(), sb.ContainerID(), err)
 		}
 
 		// Remove IP alias from the VIP to the endpoint