Obtain local pods from kubelet

probe/kubernetes/kubelet.go

@@ -0,0 +1,38 @@
+package kubernetes
+
+import (
+	"net/http"
+
+	"github.com/ugorji/go/codec"
+)
+
+// KubeletURL is just exported for testing
+var KubeletURL = "http://localhost:10255"
+
+// Intentionally not using the full kubernetes library DS
+// to make parsing faster and more tolerant to schema changes
+type podList struct {
+	Items []struct {
+		Metadata struct {
+			UID string `json:"uid"`
+		} `json:"metadata"`
+	} `json:"items"`
+}
+
+// GetLocalPodUIDs obtains the UID of the pods run locally (it's just exported for testing)
+var GetLocalPodUIDs = func() (map[string]struct{}, error) {
+	resp, err := http.Get(KubeletURL + "/pods/")
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	var localPods podList
+	if err := codec.NewDecoder(resp.Body, &codec.JsonHandle{}).Decode(&localPods); err != nil {
+		return nil, err
+	}
+	result := make(map[string]struct{}, len(localPods.Items))
+	for _, pod := range localPods.Items {
+		result[pod.Metadata.UID] = struct{}{}
+	}
+	return result, nil
+}

probe/kubernetes/kubelet_test.go

@@ -0,0 +1,73 @@
+package kubernetes_test
+
+import (
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/weaveworks/scope/probe/kubernetes"
+)
+
+const kubeletPodsJSONFile = "kubelet_pods.json"
+
+// obtained with jq .items[].metadata.uid < kubelet_pods.json
+var expectedPodUIDs = []string{
+	"af1b5325-d8cf-11e6-84fa-0800278a0c83",
+	"afeb8017-d8cf-11e6-84fa-0800278a0c83",
+	"b57a1ada-d8cf-11e6-84fa-0800278a0c83",
+	"00915ccb-dbd5-11e6-84fa-0800278a0c83",
+	"009a3d10-dbd5-11e6-84fa-0800278a0c83",
+	"fa8320c0-d8b0-11e6-828c-0800278a0c83",
+	"fa95ebae-d8b0-11e6-828c-0800278a0c83",
+	"af274a9e-d8cf-11e6-84fa-0800278a0c83",
+	"af628fd4-d8cf-11e6-84fa-0800278a0c83",
+	"af7f1d33-d8cf-11e6-84fa-0800278a0c83",
+	"b0104177-d8cf-11e6-84fa-0800278a0c83",
+	"b64d652b-d8cf-11e6-84fa-0800278a0c83",
+	"b687c058-d8cf-11e6-84fa-0800278a0c83",
+	"b0037e94-d8cf-11e6-84fa-0800278a0c83",
+	"b56298ba-d8cf-11e6-84fa-0800278a0c83",
+	"b613f0e9-d8cf-11e6-84fa-0800278a0c83",
+	"fa2eadd4-d8d1-11e6-84fa-0800278a0c83",
+	"af973584-d8cf-11e6-84fa-0800278a0c83",
+	"b079da0b-d8cf-11e6-84fa-0800278a0c83",
+	"b4e30a10-d8cf-11e6-84fa-0800278a0c83",
+	"b5025f49-d8cf-11e6-84fa-0800278a0c83",
+	"b52170e8-d8cf-11e6-84fa-0800278a0c83",
+	"b53e9d66-d8cf-11e6-84fa-0800278a0c83",
+	"b5c4c8c3-d8cf-11e6-84fa-0800278a0c83",
+	"014fb8f91f3d52450a942179a984bc15",
+}
+
+func TestGetLocalPodUIDs(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path != "/pods/" {
+				t.Fatalf("unexpected path: %s", r.URL.Path)
+			}
+			b, err := ioutil.ReadFile(kubeletPodsJSONFile)
+			if err != nil {
+				t.Fatalf("unexpected error reading json file: %v", err)
+			}
+			w.Write(b)
+		},
+	))
+	defer server.Close()
+	var savedKubeletURL string
+	savedKubeletURL, kubernetes.KubeletURL = kubernetes.KubeletURL, server.URL
+	defer func() { kubernetes.KubeletURL = savedKubeletURL }()
+
+	uids, err := kubernetes.GetLocalPodUIDs()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(expectedPodUIDs) != len(uids) {
+		t.Errorf("nnexpected length in pod UIDs (%d): expected %d", len(uids), len(expectedPodUIDs))
+	}
+	for _, expectedUID := range expectedPodUIDs {
+		if _, ok := uids[expectedUID]; !ok {
+			t.Errorf("uid not found: %s", expectedUID)
+		}
+	}
+}

probe/kubernetes/reporter.go

@@ -1,13 +1,11 @@
 package kubernetes
 
 import (
-	"io/ioutil"
-	"os"
 	"strings"
 
-	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/labels"
 
+	log "github.com/Sirupsen/logrus"
 	"github.com/weaveworks/common/mtime"
 	"github.com/weaveworks/scope/probe"
 	"github.com/weaveworks/scope/probe/controls"
@@ -314,27 +312,6 @@ func (r *Reporter) replicaSetTopology(probeID string, deployments []Deployment)
 	return result, replicaSets, err
 }
 
-// GetNodeName return the k8s node name for the current machine.
-// It is exported for testing.
-var GetNodeName = func(r *Reporter) (string, error) {
-	uuidBytes, err := ioutil.ReadFile("/sys/class/dmi/id/product_uuid")
-	if os.IsNotExist(err) {
-		uuidBytes, err = ioutil.ReadFile("/sys/hypervisor/uuid")
-	}
-	if err != nil {
-		return "", err
-	}
-	uuid := strings.Trim(string(uuidBytes), "\n")
-	nodeName := ""
-	err = r.client.WalkNodes(func(node *api.Node) error {
-		if node.Status.NodeInfo.SystemUUID == string(uuid) {
-			nodeName = node.ObjectMeta.Name
-		}
-		return nil
-	})
-	return nodeName, err
-}
-
 type labelledChild interface {
 	Labels() map[string]string
 	AddParent(string, string)
@@ -387,13 +364,24 @@ func (r *Reporter) podTopology(services []Service, replicaSets []ReplicaSet) (re
 		))
 	}
 
-	thisNodeName, err := GetNodeName(r)
-	if err != nil {
-		return pods, err
+	// Obtain the local pods from kubelet since we only want to report those
+	// for performance reasons.
+	//
+	// In theory a simpler approach would be to obtain the current NodeName
+	// and filter local pods based on that. However that's hard since
+	// 1. reconstructing the NodeName requires cloud provider credentials
+	// 2. inferring the NodeName out of the hostname or system uuid is unreliable
+	//    (uuids and hostnames can be duplicated across the cluster).
+	localPodUIDs, errUIDs := GetLocalPodUIDs()
+	if errUIDs != nil {
+		log.Warnf("Cannot obtain local pods, reporting all (which may impact performance): %v", errUIDs)
 	}
-	err = r.client.WalkPods(func(p Pod) error {
-		if p.NodeName() != thisNodeName {
-			return nil
+	err := r.client.WalkPods(func(p Pod) error {
+		// filter out non-local pods
+		if errUIDs != nil {
+			if _, ok := localPodUIDs[p.UID()]; !ok {
+				return nil
+			}
 		}
 		for _, selector := range selectors {
 			selector(p)

probe/kubernetes/reporter_test.go

@@ -180,10 +180,14 @@ func (c mockPipeClient) PipeClose(appID, id string) error {
 }
 
 func TestReporter(t *testing.T) {
-	oldGetNodeName := kubernetes.GetNodeName
-	defer func() { kubernetes.GetNodeName = oldGetNodeName }()
-	kubernetes.GetNodeName = func(*kubernetes.Reporter) (string, error) {
-		return nodeName, nil
+	oldGetNodeName := kubernetes.GetLocalPodUIDs
+	defer func() { kubernetes.GetLocalPodUIDs = oldGetNodeName }()
+	kubernetes.GetLocalPodUIDs = func() (map[string]struct{}, error) {
+		uids := map[string]struct{}{
+			pod1UID: {},
+			pod2UID: {},
+		}
+		return uids, nil
 	}
 
 	pod1ID := report.MakePodNodeID(pod1UID)
@@ -271,10 +275,10 @@ type callbackReadCloser struct {
 func (c *callbackReadCloser) Close() error { return c.close() }
 
 func TestReporterGetLogs(t *testing.T) {
-	oldGetNodeName := kubernetes.GetNodeName
-	defer func() { kubernetes.GetNodeName = oldGetNodeName }()
-	kubernetes.GetNodeName = func(*kubernetes.Reporter) (string, error) {
-		return nodeName, nil
+	oldGetNodeName := kubernetes.GetLocalPodUIDs
+	defer func() { kubernetes.GetLocalPodUIDs = oldGetNodeName }()
+	kubernetes.GetLocalPodUIDs = func() (map[string]struct{}, error) {
+		return map[string]struct{}{}, nil
 	}
 
 	client := newMockClient()