don't map image adjacencies to hosts

it's just wrong

render/host.go

@@ -32,11 +32,23 @@ func nodes2Hosts(nodes Nodes) Nodes {
 		if n.Topology == Pseudo {
 			continue // Don't propagate pseudo nodes - we do this in endpoints2Hosts
 		}
+		isImage := n.Topology == report.ContainerImage
 		hostIDs, _ := n.Parents.Lookup(report.Host)
 		for _, id := range hostIDs {
-			ret.addChild(n, id, func(id string) report.Node {
-				return report.MakeNode(id).WithTopology(report.Host)
-			})
+			if isImage {
+				// We need to treat image nodes specially because they
+				// aggregate adjacencies of containers across multiple
+				// hosts, and hence mapping these adjacencies to host
+				// adjacencies would produce edges that aren't present
+				// in reality.
+				ret.addUnmappedChild(n, id, func(id string) report.Node {
+					return report.MakeNode(id).WithTopology(report.Host)
+				})
+			} else {
+				ret.addChild(n, id, func(id string) report.Node {
+					return report.MakeNode(id).WithTopology(report.Host)
+				})
+			}
 		}
 	}
 	return ret.result(nodes)

render/render.go

@@ -185,6 +185,20 @@ func (ret *joinResults) add(m report.Node, n report.Node) {
 	}
 }
 
+// Add m as a child of the node at id, creating a new result node if
+// not already there.
+func (ret *joinResults) addUnmappedChild(m report.Node, id string, create func(string) report.Node) {
+	result, exists := ret.nodes[id]
+	if !exists {
+		result = create(id)
+	}
+	result.Children = result.Children.Add(m)
+	if m.Topology != report.Endpoint { // optimisation: we never look at endpoint counts
+		result.Counters = result.Counters.Add(m.Topology, 1)
+	}
+	ret.nodes[id] = result
+}
+
 // Add m as a child of the node at id, creating a new result node if
 // not already there, and updating the mapping from old ID to new ID.
 func (ret *joinResults) addChild(m report.Node, id string, create func(string) report.Node) {