Merge pull request #976 from weaveworks/955-weave-tagger-crash

Fix weave tagger crash

probe/kubernetes/reporter.go

@@ -1,8 +1,10 @@
 package kubernetes
 
 import (
-	"github.com/weaveworks/scope/report"
 	"k8s.io/kubernetes/pkg/labels"
+
+	"github.com/weaveworks/scope/probe/docker"
+	"github.com/weaveworks/scope/report"
 )
 
 // Reporter generate Reports containing Container and ContainerImage topologies
@@ -66,11 +68,12 @@ func (r *Reporter) podTopology(services []Service) (report.Topology, report.Topo
 		nodeID := report.MakePodNodeID(p.Namespace(), p.Name())
 		pods = pods.AddNode(nodeID, p.GetNode())
 
-		container := report.MakeNodeWith(map[string]string{
-			PodID:     p.ID(),
-			Namespace: p.Namespace(),
-		}).WithParents(report.EmptySets.Add(report.Pod, report.MakeStringSet(nodeID)))
 		for _, containerID := range p.ContainerIDs() {
+			container := report.MakeNodeWith(map[string]string{
+				PodID:              p.ID(),
+				Namespace:          p.Namespace(),
+				docker.ContainerID: containerID,
+			}).WithParents(report.EmptySets.Add(report.Pod, report.MakeStringSet(nodeID)))
 			containers.AddNode(report.MakeContainerNodeID(containerID), container)
 		}
 		return nil

probe/overlay/weave.go

@@ -134,9 +134,15 @@ func (w *Weave) Tag(r report.Report) (report.Report, error) {
 	}
 
 	// Put information from weave ps on the container nodes
+	const maxPrefixSize = 12
 	for id, node := range r.Container.Nodes {
-		prefix, _ := node.Latest.Lookup(docker.ContainerID)
-		prefix = prefix[:12]
+		prefix, ok := node.Latest.Lookup(docker.ContainerID)
+		if !ok {
+			continue
+		}
+		if len(prefix) > maxPrefixSize {
+			prefix = prefix[:maxPrefixSize]
+		}
 		entry, ok := w.psCache[prefix]
 		if !ok {
 			continue