From 27e38e96ea330d05d18bd3170a1904b630e36715 Mon Sep 17 00:00:00 2001
From: "Benjamin A. Petersen" <ben@benjaminapetersen.me>
Date: Tue, 10 Dec 2019 09:59:08 -0500
Subject: [PATCH] Ensure route.host has a value before tracking console_url
 metric to a ""

---
 pkg/console/metrics/console_url.go | 47 ++++++++++++++++++++++++++++++
 pkg/console/metrics/register.go    | 31 ++++++++++++++++++++
 pkg/console/operator/sync_v400.go  | 15 +++-------
 3 files changed, 82 insertions(+), 11 deletions(-)
 create mode 100644 pkg/console/metrics/console_url.go
 create mode 100644 pkg/console/metrics/register.go

diff --git a/pkg/console/metrics/console_url.go b/pkg/console/metrics/console_url.go
new file mode 100644
index 000000000..6e6dc1a2f
--- /dev/null
+++ b/pkg/console/metrics/console_url.go
@@ -0,0 +1,47 @@
+package metrics
+
+import "k8s.io/klog"
+
+func HandleConsoleURL(oldURL, newURL string) {
+	// if neither have been set, there is nothing to update
+	if noHost(oldURL, newURL) {
+		klog.V(4).Infof("metric console_url has no host")
+		return
+	}
+
+	// only a new URL
+	if isNewHost(oldURL, newURL) {
+		klog.V(4).Infof("metric console_url new host: %s %s", oldURL, newURL)
+		singleton.ConsoleURL.WithLabelValues(newURL).Set(1)
+		return
+	}
+
+	// route or ingress update
+	if isHostTransition(oldURL, newURL) {
+		klog.V(4).Infof("metric console_url host transition: %s to %s", oldURL, newURL)
+		singleton.ConsoleURL.WithLabelValues(oldURL).Set(0)
+		singleton.ConsoleURL.WithLabelValues(newURL).Set(1)
+		return
+	}
+
+	// something went wrong and we no longer have a route or ingress with a host
+	if hostDied(oldURL, newURL) {
+		klog.V(4).Infof("metric console_url host lost: %s %s", oldURL, newURL)
+		singleton.ConsoleURL.WithLabelValues(oldURL).Set(0)
+		return
+	}
+	klog.Error("metric console_url unhandled")
+}
+
+func noHost(old, new string) bool {
+	return len(old) == 0 && len(new) == 0
+}
+func isNewHost(old, new string) bool {
+	return len(old) == 0 && len(new) != 0
+}
+func isHostTransition(old, new string) bool {
+	return len(old) != 0 && len(new) != 0
+}
+func hostDied(old, new string) bool {
+	return len(old) != 0 && len(new) == 0
+}
diff --git a/pkg/console/metrics/register.go b/pkg/console/metrics/register.go
new file mode 100644
index 000000000..6f8670117
--- /dev/null
+++ b/pkg/console/metrics/register.go
@@ -0,0 +1,31 @@
+package metrics
+
+import (
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type ConsoleMetrics struct {
+	ConsoleURL *prometheus.GaugeVec
+}
+
+var singleton *ConsoleMetrics
+var once sync.Once
+
+func Register() *ConsoleMetrics {
+	// thread safe
+	once.Do(func() {
+		singleton = &ConsoleMetrics{}
+
+		// metric: console_url{url="https://<url>"} 1
+		singleton.ConsoleURL = prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Name: "console_url",
+			Help: "URL of the console exposed on the cluster",
+			// one label
+		}, []string{"url"})
+
+		prometheus.MustRegister(singleton.ConsoleURL)
+	})
+	return singleton
+}
diff --git a/pkg/console/operator/sync_v400.go b/pkg/console/operator/sync_v400.go
index c93724aef..5a7affdff 100644
--- a/pkg/console/operator/sync_v400.go
+++ b/pkg/console/operator/sync_v400.go
@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/openshift/console-operator/pkg/console/metrics"
+
 	"github.com/prometheus/client_golang/prometheus"
 
 	// kube
@@ -212,22 +214,13 @@ func (co *consoleOperator) sync_v400(updatedOperatorConfig *operatorv1.Console,
 }
 
 func (co *consoleOperator) SyncConsoleConfig(consoleConfig *configv1.Console, consoleURL string) (*configv1.Console, error) {
+	oldURL := consoleConfig.Status.ConsoleURL
 	updated := consoleConfig.DeepCopy()
-
-	// track the URL state in prometheus before we update it
-	if consoleConfig.Status.ConsoleURL != consoleURL {
-		// not using this URL anymore
-		consoleURLMetric.WithLabelValues(consoleConfig.Status.ConsoleURL).Set(0)
-	}
-	if len(consoleURL) != 0 {
-		// only update to new if we have a url
-		consoleURLMetric.WithLabelValues(consoleURL).Set(1)
-	}
-
 	if updated.Status.ConsoleURL != consoleURL {
 		klog.V(4).Infof("updating console.config.openshift.io with url: %v", consoleURL)
 		updated.Status.ConsoleURL = consoleURL
 	}
+	metrics.HandleConsoleURL(oldURL, consoleURL)
 	return co.consoleConfigClient.UpdateStatus(updated)
 }