Add alert-expression console links to notifications.

The ConsoleLinkForExpression() function now escapes console URLs in such a way
that works both in emails and in HTML.

Change-Id: I917bae0b526cbbac28ccd2a4ec3c5ac03ee4c647

main.go

@@ -203,14 +203,19 @@ func main() {
 	notifications := make(chan notification.NotificationReqs, *notificationQueueCapacity)
 
 	// Queue depth will need to be exposed
-	ruleManager := rules.NewRuleManager(unwrittenSamples, notifications, conf.EvaluationInterval(), ts)
+	ruleManager := rules.NewRuleManager(&rules.RuleManagerOptions{
+		Results:            unwrittenSamples,
+		Notifications:      notifications,
+		EvaluationInterval: conf.EvaluationInterval(),
+		Storage:            ts,
+		PrometheusUrl:      web.MustBuildServerUrl(),
+	})
 	if err := ruleManager.AddRulesFromConfig(conf); err != nil {
 		glog.Fatal("Error loading rule files: ", err)
 	}
 	go ruleManager.Run()
 
-	prometheusUrl := web.MustBuildServerUrl()
-	notificationHandler := notification.NewNotificationHandler(*alertmanagerUrl, prometheusUrl, notifications)
+	notificationHandler := notification.NewNotificationHandler(*alertmanagerUrl, notifications)
 	go notificationHandler.Run()
 
 	flags := map[string]string{}

notification/notification.go

@@ -54,6 +54,8 @@ type NotificationReq struct {
 	ActiveSince time.Time
 	// A textual representation of the rule that triggered the alert.
 	RuleString string
+	// Prometheus console link to alert expression.
+	GeneratorUrl string
 }
 
 type NotificationReqs []*NotificationReq
@@ -67,8 +69,6 @@ type httpPoster interface {
 type NotificationHandler struct {
 	// The URL of the alert manager to send notifications to.
 	alertmanagerUrl string
-	// The URL of this Prometheus instance to include in notifications.
-	prometheusUrl string
 	// Buffer of notifications that have not yet been sent.
 	pendingNotifications <-chan NotificationReqs
 	// HTTP client with custom timeout settings.
@@ -76,12 +76,11 @@ type NotificationHandler struct {
 }
 
 // Construct a new NotificationHandler.
-func NewNotificationHandler(alertmanagerUrl string, prometheusUrl string, notificationReqs <-chan NotificationReqs) *NotificationHandler {
+func NewNotificationHandler(alertmanagerUrl string, notificationReqs <-chan NotificationReqs) *NotificationHandler {
 	return &NotificationHandler{
 		alertmanagerUrl:      alertmanagerUrl,
 		pendingNotifications: notificationReqs,
 		httpClient:           utility.NewDeadlineClient(*deadline),
-		prometheusUrl:        prometheusUrl,
 	}
 }
 
@@ -132,7 +131,7 @@ func (n *NotificationHandler) sendNotifications(reqs NotificationReqs) error {
 			"Payload": map[string]interface{}{
 				"Value":        req.Value,
 				"ActiveSince":  req.ActiveSince,
-				"GeneratorUrl": n.prometheusUrl,
+				"GeneratorUrl": req.GeneratorUrl,
 				"AlertingRule": req.RuleString,
 			},
 		})

notification/notification_test.go

@@ -48,7 +48,7 @@ type testNotificationScenario struct {
 func (s *testNotificationScenario) test(i int, t *testing.T) {
 	notifications := make(chan NotificationReqs)
 	defer close(notifications)
-	h := NewNotificationHandler("alertmanager_url", "prometheus_url", notifications)
+	h := NewNotificationHandler("alertmanager_url", notifications)
 
 	receivedPost := make(chan bool, 1)
 	poster := testHttpPoster{receivedPost: receivedPost}
@@ -66,6 +66,7 @@ func (s *testNotificationScenario) test(i int, t *testing.T) {
 			Value:        clientmodel.SampleValue(1.0 / 3.0),
 			ActiveSince:  time.Time{},
 			RuleString:   "Test rule string",
+			GeneratorUrl: "prometheus_url",
 		},
 	}
 

rules/helpers.go

@@ -15,7 +15,8 @@ package rules
 
 import (
 	"fmt"
-	"html"
+	"net/url"
+	"strings"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 
@@ -116,5 +117,13 @@ func NewMatrix(vector ast.Node, intervalStr string) (ast.MatrixNode, error) {
 }
 
 func ConsoleLinkForExpression(expr string) string {
-	return html.EscapeString(fmt.Sprintf(`graph#[{"expr":%q,"tab":1}]`, expr))
+	// url.QueryEscape percent-escapes everything except spaces, for which it
+	// uses "+". However, in the non-query part of a URI, only percent-escaped
+	// spaces are legal, so we need to manually replace "+" with "%20" after
+	// query-escaping the string.
+	//
+	// See also:
+	// http://stackoverflow.com/questions/1634271/url-encoding-the-space-character-or-20.
+	urlData := url.QueryEscape(fmt.Sprintf(`[{"expr":%q,"tab":1}]`, expr))
+	return fmt.Sprintf("/graph#%s", strings.Replace(urlData, "+", "%20", -1))
 }

rules/manager.go

@@ -45,21 +45,37 @@ type ruleManager struct {
 	sync.Mutex
 	rules []Rule
 
-	results       chan<- *extraction.Result
-	notifications chan<- notification.NotificationReqs
 	done chan bool
+
 	interval time.Duration
 	storage  *metric.TieredStorage
+
+	results       chan<- *extraction.Result
+	notifications chan<- notification.NotificationReqs
+
+	prometheusUrl string
 }
 
-func NewRuleManager(results chan<- *extraction.Result, notifications chan<- notification.NotificationReqs, interval time.Duration, storage *metric.TieredStorage) RuleManager {
+type RuleManagerOptions struct {
+	EvaluationInterval time.Duration
+	Storage            *metric.TieredStorage
+
+	Notifications chan<- notification.NotificationReqs
+	Results       chan<- *extraction.Result
+
+	PrometheusUrl string
+}
+
+func NewRuleManager(o *RuleManagerOptions) RuleManager {
 	manager := &ruleManager{
-		results:       results,
-		notifications: notifications,
 		rules: []Rule{},
 		done:  make(chan bool),
-		interval:      interval,
-		storage:       storage,
+
+		interval:      o.EvaluationInterval,
+		storage:       o.Storage,
+		results:       o.Results,
+		notifications: o.Notifications,
+		prometheusUrl: o.PrometheusUrl,
 	}
 	return manager
 }
@@ -110,6 +126,7 @@ func (m *ruleManager) queueAlertNotifications(rule *AlertingRule) {
 			Value:        aa.Value,
 			ActiveSince:  aa.ActiveSince,
 			RuleString:   rule.String(),
+			GeneratorUrl: m.prometheusUrl + ConsoleLinkForExpression(rule.vector.String()),
 		})
 	}
 	m.notifications <- notifications