feat(api): add an enpoint that returns all known label values for given label name

This will be used in the silence form, to provide a list of suggestions

autocomplete.go

@@ -61,3 +61,43 @@ func knownLabelNames(c *gin.Context) {
 	c.Data(http.StatusOK, gin.MIMEJSON, data.([]byte))
 	logAlertsView(c, "MIS", time.Since(start))
 }
+
+func knownLabelValues(c *gin.Context) {
+	noCache(c)
+	start := time.Now()
+
+	cacheKey := c.Request.RequestURI
+	if cacheKey == "" {
+		// FIXME c.Request.RequestURI is empty when running tests for some reason
+		// needs checking, below acts as a workaround
+		cacheKey = c.Request.URL.RawQuery
+	}
+
+	data, found := apiCache.Get(cacheKey)
+	if found {
+		c.Data(http.StatusOK, gin.MIMEJSON, data.([]byte))
+		logAlertsView(c, "HIT", time.Since(start))
+		return
+	}
+
+	name, found := c.GetQuery("name")
+	if !found || name == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "missing name=<token> parameter"})
+		log.Infof("[%s] <%d> %s %s took %s", c.ClientIP(), http.StatusBadRequest, c.Request.Method, c.Request.RequestURI, time.Since(start))
+		return
+	}
+
+	values := alertmanager.DedupKnownLabelValues(name)
+	sort.Strings(values)
+
+	data, err := json.Marshal(values)
+	if err != nil {
+		log.Error(err.Error())
+		panic(err)
+	}
+
+	apiCache.Set(cacheKey, data, time.Second*15)
+
+	c.Data(http.StatusOK, gin.MIMEJSON, data.([]byte))
+	logAlertsView(c, "MIS", time.Since(start))
+}

autocomplete_test.go

@@ -34,7 +34,7 @@ var labelTests = []labelTest{
 	},
 }
 
-func TestKnownLabels(t *testing.T) {
+func TestKnownLabelNames(t *testing.T) {
 	mockConfig()
 	for _, version := range mock.ListAllMocks() {
 		t.Logf("Testing known labels using mock files from Alertmanager %s", version)
@@ -68,3 +68,58 @@ func TestKnownLabels(t *testing.T) {
 		}
 	}
 }
+
+type valueTest struct {
+	Name    string
+	Results []string
+}
+
+var valueTests = []valueTest{
+	{
+		Name:    "foobar",
+		Results: []string{},
+	},
+	{
+		Name:    "alertname",
+		Results: []string{"Free_Disk_Space_Too_Low", "HTTP_Probe_Failed", "Host_Down", "Memory_Usage_Too_High"},
+	},
+	{
+		Name:    "cluster",
+		Results: []string{"dev", "prod", "staging"},
+	},
+}
+
+func TestKnownLabelValues(t *testing.T) {
+	mockConfig()
+	for _, version := range mock.ListAllMocks() {
+		t.Logf("Testing known label values using mock files from Alertmanager %s", version)
+		mockAlerts(version)
+		r := ginTestEngine()
+
+		req, _ := http.NewRequest("GET", "/labelValues.json", nil)
+		resp := httptest.NewRecorder()
+		r.ServeHTTP(resp, req)
+		if resp.Code != http.StatusBadRequest {
+			t.Errorf("Invalid status code for request without any query: %d", resp.Code)
+		}
+
+		for _, testCase := range valueTests {
+			url := fmt.Sprintf("/labelValues.json?name=%s", testCase.Name)
+			req, _ := http.NewRequest("GET", url, nil)
+			resp := httptest.NewRecorder()
+			r.ServeHTTP(resp, req)
+
+			if resp.Code != http.StatusOK {
+				t.Errorf("GET %s returned status %d", url, resp.Code)
+			}
+
+			ur := []string{}
+			json.Unmarshal(resp.Body.Bytes(), &ur)
+
+			if len(ur) != len(testCase.Results) {
+				t.Errorf("Invalid number of label values for %s, got %d, expected %d", url, len(ur), len(testCase.Results))
+				t.Errorf("Results: %s", ur)
+			}
+		}
+	}
+}

internal/alertmanager/dedup.go

@@ -180,3 +180,25 @@ func DedupKnownLabels() []string {
 	}
 	return flatLabels
 }
+
+// DedupKnownLabelValues returns a list of all known values for label $name
+func DedupKnownLabelValues(name string) []string {
+	dedupedValues := map[string]bool{}
+	upstreams := GetAlertmanagers()
+
+	for _, am := range upstreams {
+		for _, ag := range am.Alerts() {
+			for _, alert := range ag.Alerts {
+				if val, found := alert.Labels[name]; found {
+					dedupedValues[val] = true
+				}
+			}
+		}
+	}
+
+	flatValues := []string{}
+	for key := range dedupedValues {
+		flatValues = append(flatValues, key)
+	}
+	return flatValues
+}

main.go

@@ -69,6 +69,7 @@ func setupRouter(router *gin.Engine) {
 	router.GET(getViewURL("/alerts.json"), alerts)
 	router.GET(getViewURL("/autocomplete.json"), autocomplete)
 	router.GET(getViewURL("/labelNames.json"), knownLabelNames)
+	router.GET(getViewURL("/labelValues.json"), knownLabelValues)
 	router.NoRoute(notFound)
 }