Draw container IDs in /containers from both container and app metrics (…

…#116)

* Update signature of test setup method

This will allow the same method to be used without sending all the test
data.

* Populate /containers from app and container metrics

This commit adds a test which supplies node and app metrics, but no
container metrics. This fails without the accompanying fix, which draws
app and container metrics from the store and extracts the set of unique
container IDs from them.

* Restore accidentally-removed build flag

I would normally squash this fix in, but a downstream DC/OS PR is
depending on a specific commit hash, so I'm not going to do so. It will
get squashed when we merge.

* Rename allTestData to allTestMessages

* Improve readability of containers test case

producers/http/handlers.go

@@ -51,7 +51,13 @@ func nodeHandler(p *producerImpl) http.HandlerFunc {
 func containersHandler(p *producerImpl) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		cm := []string{}
-		containerMetrics, err := p.store.GetByRegex(regexp.QuoteMeta(producers.ContainerMetricPrefix) + ".*")
+		containerMetrics, err := p.store.GetByRegex(
+			fmt.Sprintf(
+				"(%s|%s).*",
+				regexp.QuoteMeta(producers.ContainerMetricPrefix),
+				regexp.QuoteMeta(producers.AppMetricPrefix),
+			),
+		)
 		if err != nil {
 			httpLog.Errorf("/v0/containers - %s", err.Error())
 			http.Error(w, err.Error(), http.StatusInternalServerError)

producers/http/handlers_test.go

@@ -86,9 +86,15 @@ var (
 		},
 		Timestamp: testTime.UTC().Unix(),
 	}
+
+	allTestMessages = []producers.MetricsMessage{
+		testNodeData,
+		testContainerData,
+		testAppData,
+	}
 )
 
-func setup() int {
+func setup(messages []producers.MetricsMessage) int {
 	port, err := getEphemeralPort()
 	if err != nil {
 		panic(err)
@@ -102,17 +108,17 @@ func setup() int {
 	go pi.Run()
 	time.Sleep(1 * time.Second) // give the http server a chance to start before querying it
 
-	pc <- testNodeData
-	pc <- testContainerData
-	pc <- testAppData
+	for _, m := range messages {
+		pc <- m
+	}
 
 	return port
 }
 
 func TestNodeHandler(t *testing.T) {
 	Convey("When querying the /v0/node endpoint", t, func() {
 		Convey("Should return metrics in the expected structure", func() {
-			port := setup()
+			port := setup(allTestMessages)
 			resp, err := http.Get(urlBuilder("localhost", port, "/v0/node"))
 			if err != nil {
 				panic(err)
@@ -138,7 +144,7 @@ func TestNodeHandler(t *testing.T) {
 func TestContainersHandler(t *testing.T) {
 	Convey("When querying the /v0/containers endpoint", t, func() {
 		Convey("Should return container IDs in the expected structure", func() {
-			port := setup()
+			port := setup(allTestMessages)
 			resp, err := http.Get(urlBuilder("localhost", port, "/v0/containers"))
 			if err != nil {
 				panic(err)
@@ -157,13 +163,30 @@ func TestContainersHandler(t *testing.T) {
 			So(resp.StatusCode, ShouldEqual, http.StatusOK)
 			So(strings.TrimSpace(string(got)), ShouldEqual, strings.TrimSpace(string(expected)))
 		})
+		Convey("Should return container IDs when app metrics, but not container metrics, are present", func() {
+			port := setup([]producers.MetricsMessage{testNodeData, testAppData})
+			resp, err := http.Get(urlBuilder("localhost", port, "/v0/containers"))
+			if err != nil {
+				panic(err)
+			}
+			defer resp.Body.Close()
+
+			// Note that we didn't supply testContainerData in `setup` above.
+			var containerIDs []string
+			if err := json.NewDecoder(resp.Body).Decode(&containerIDs); err != nil {
+				panic(err)
+			}
+
+			So(resp.StatusCode, ShouldEqual, http.StatusOK)
+			So(containerIDs, ShouldResemble, []string{testContainerData.Dimensions.ContainerID})
+		})
 	})
 }
 
 func TestContainerHandler(t *testing.T) {
 	Convey("When querying the /v0/containers/{id} endpoint", t, func() {
 		Convey("Should return container metrics for the container ID given", func() {
-			port := setup()
+			port := setup(allTestMessages)
 			resp, err := http.Get(urlBuilder("localhost", port, "/v0/containers/foo-container"))
 			if err != nil {
 				panic(err)
@@ -188,7 +211,7 @@ func TestContainerHandler(t *testing.T) {
 func TestContainerAppHandler(t *testing.T) {
 	Convey("When querying the /v0/containers/{id}/app endpoint", t, func() {
 		Convey("Should return app metrics in the expected structure", func() {
-			port := setup()
+			port := setup(allTestMessages)
 			resp, err := http.Get(urlBuilder("localhost", port, "/v0/containers/foo-container/app"))
 			if err != nil {
 				panic(err)
@@ -213,7 +236,7 @@ func TestContainerAppHandler(t *testing.T) {
 func TestContainerAppMetricHandler(t *testing.T) {
 	Convey("When querying the /v0/containers/{id}/app/{metric-id} endpoint", t, func() {
 		Convey("Should return app metrics in the expected structure", func() {
-			port := setup()
+			port := setup(allTestMessages)
 			resp, err := http.Get(urlBuilder("localhost", port, "/v0/containers/foo-container/app/some-app-metric"))
 			if err != nil {
 				panic(err)
@@ -238,7 +261,7 @@ func TestContainerAppMetricHandler(t *testing.T) {
 func TestPingHandler(t *testing.T) {
 	Convey("When querying the /v0/ping endpoint", t, func() {
 		Convey("Should return a message and a timestamp", func() {
-			port := setup()
+			port := setup(allTestMessages)
 			resp, err := http.Get(urlBuilder("localhost", port, "/v0/ping"))
 			if err != nil {
 				panic(err)