When k8s present, allow filtering of containers by namespace

To facilitate this, we replace the existing functionality of updateFilters which
sets k8s topologies to have the filters [namespace, managed], to instead append the namespace filter
to any existing. This lets it apply to both k8s and container topologies without overwriting existing
container filters. We instead set the managed filter in the static definition.

This however has the side effect that the ordering of the namespace filter and the managed filter
in k8s topologies has been reversed, so it reads:
	Show Unmanaged | Hide Unmanaged
	foo | bar | default | baz | All Namespaces
instead of:
	foo | bar | default | baz | All Namespaces
	Show Unmanaged | Hide Unmanaged

app/api_topologies.go

@@ -80,21 +80,23 @@ func updateFilters(rpt report.Report, topologies []APITopologyDesc) []APITopolog
 		ns = append(ns, namespace)
 	}
 	sort.Strings(ns)
-	for i, t := range topologies {
-		if t.id == podsID || t.id == servicesID || t.id == deploymentsID || t.id == replicaSetsID {
-			topologies[i] = updateTopologyFilters(t, []APITopologyOptionGroup{
-				kubernetesFilters(ns...), unmanagedFilter,
-			})
+	if len(ns) > 0 { // We only want to apply k8s filters when we have k8s-related nodes
+		for i, t := range topologies {
+			if t.id == containersID || t.id == containersByImageID || t.id == containersByHostnameID || t.id == podsID || t.id == servicesID || t.id == deploymentsID || t.id == replicaSetsID {
+				topologies[i] = mergeTopologyFilters(t, []APITopologyOptionGroup{
+					kubernetesFilters(ns...),
+				})
+			}
 		}
 	}
 	return topologies
 }
 
-// updateTopologyFilters recursively sets the options on a topology description
-func updateTopologyFilters(t APITopologyDesc, options []APITopologyOptionGroup) APITopologyDesc {
-	t.Options = options
+// mergeTopologyFilters recursively merges in new options on a topology description
+func mergeTopologyFilters(t APITopologyDesc, options []APITopologyOptionGroup) APITopologyDesc {
+	t.Options = append(t.Options, options...)
 	for i, sub := range t.SubTopologies {
-		t.SubTopologies[i] = updateTopologyFilters(sub, options)
+		t.SubTopologies[i] = mergeTopologyFilters(sub, options)
 	}
 	return t
 }
@@ -200,6 +202,7 @@ func MakeRegistry() *Registry {
 			renderer:    render.PodRenderer,
 			Name:        "Pods",
 			Rank:        3,
+			Options:     []APITopologyOptionGroup{unmanagedFilter},
 			HideIfEmpty: true,
 		},
 		APITopologyDesc{
@@ -207,6 +210,7 @@ func MakeRegistry() *Registry {
 			parent:      podsID,
 			renderer:    render.ReplicaSetRenderer,
 			Name:        "replica sets",
+			Options:     []APITopologyOptionGroup{unmanagedFilter},
 			HideIfEmpty: true,
 		},
 		APITopologyDesc{
@@ -214,6 +218,7 @@ func MakeRegistry() *Registry {
 			parent:      podsID,
 			renderer:    render.DeploymentRenderer,
 			Name:        "deployments",
+			Options:     []APITopologyOptionGroup{unmanagedFilter},
 			HideIfEmpty: true,
 		},
 		APITopologyDesc{
@@ -221,6 +226,7 @@ func MakeRegistry() *Registry {
 			parent:      podsID,
 			renderer:    render.PodServiceRenderer,
 			Name:        "services",
+			Options:     []APITopologyOptionGroup{unmanagedFilter},
 			HideIfEmpty: true,
 		},
 		APITopologyDesc{

render/filters.go

@@ -10,6 +10,10 @@ import (
 	"github.com/weaveworks/scope/report"
 )
 
+const (
+	k8sNamespaceLabel = "io.kubernetes.pod.namespace"
+)
+
 // PreciousNodeRenderer ensures a node is never filtered out by decorators
 type PreciousNodeRenderer struct {
 	PreciousNodeID string
@@ -254,7 +258,7 @@ func IsApplication(n report.Node) bool {
 	if roleLabel == "system" {
 		return false
 	}
-	namespace, _ := n.Latest.Lookup(docker.LabelPrefix + "io.kubernetes.pod.namespace")
+	namespace, _ := n.Latest.Lookup(docker.LabelPrefix + k8sNamespaceLabel)
 	if namespace == "kube-system" {
 		return false
 	}
@@ -293,7 +297,14 @@ func IsNotPseudo(n report.Node) bool {
 // IsNamespace checks if the node is a pod/service in the specified namespace
 func IsNamespace(namespace string) FilterFunc {
 	return func(n report.Node) bool {
-		gotNamespace, _ := n.Latest.Lookup(kubernetes.Namespace)
+		tryKeys := []string{kubernetes.Namespace, docker.LabelPrefix + k8sNamespaceLabel}
+		gotNamespace := ""
+		for _, key := range tryKeys {
+			if value, ok := n.Latest.Lookup(key); ok {
+				gotNamespace = value
+				break
+			}
+		}
 		return namespace == gotNamespace
 	}
 }