Add flag to Ignore unsuccessful assessments due to intermittent ssllabs issue

pkg/exporter/exporter.go

@@ -24,6 +24,8 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+const probeSuccessMetricName = "ssllabs_probe_success"
+
 // Handle runs SSLLabs assessment on the specified target
 // and returns a Prometheus Registry with the results
 func Handle(ctx context.Context, logger log.Logger, target string) prometheus.Gatherer {
@@ -34,7 +36,7 @@ func Handle(ctx context.Context, logger log.Logger, target string) prometheus.Ga
 			Help: "Displays how long the assessment took to complete in seconds",
 		})
 		probeSuccessGauge = prometheus.NewGauge(prometheus.GaugeOpts{
-			Name: "ssllabs_probe_success",
+			Name: probeSuccessMetricName,
 			Help: "Displays whether the assessment succeeded or not",
 		})
 
@@ -81,3 +83,20 @@ func Handle(ctx context.Context, logger log.Logger, target string) prometheus.Ga
 
 	return registry
 }
+
+// Failed checks whether the assessment failed or not
+func Failed(registry prometheus.Gatherer) bool {
+	metrics, err := registry.Gather()
+	if err != nil {
+		return false
+	}
+
+	for _, m := range metrics {
+		if m.GetName() == probeSuccessMetricName {
+			result := m.GetMetric()[0].GetGauge().Value
+			return *result == 0
+		}
+	}
+
+	return false
+}

pkg/exporter/exporter_test.go

@@ -0,0 +1,64 @@
+// Copyright 2020 Anas Ait Said Oubrahim
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package exporter
+
+import (
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func TestFailed(t *testing.T) {
+	var cases = []struct {
+		name           string
+		value          float64
+		expectedResult bool
+	}{
+		{
+			name:           "failed_assessment",
+			value:          0,
+			expectedResult: true,
+		},
+		{
+			name:           "successful_assessment",
+			value:          1,
+			expectedResult: false,
+		},
+		{
+			name:           "unregistered_metric",
+			value:          -1,
+			expectedResult: false,
+		},
+	}
+
+	for _, c := range cases {
+		// init registry
+		registry := prometheus.NewRegistry()
+		probeSuccessGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+			Name: probeSuccessMetricName,
+			Help: "Displays whether the assessment succeeded or not",
+		})
+
+		if c.value != -1 {
+			registry.MustRegister(probeSuccessGauge)
+			probeSuccessGauge.Set(c.value)
+		}
+
+		result := Failed(registry)
+		if result != c.expectedResult {
+			t.Errorf("Test case : %v failed.\nExpected : %v\nGot : %v\n", c.name, c.expectedResult, result)
+		}
+	}
+}

ssllabs_exporter.go

@@ -40,10 +40,11 @@ const (
 )
 
 var (
-	listenAddress  = kingpin.Flag("listen-address", "The address to listen on for HTTP requests.").Default(":19115").String()
-	probeTimeout   = kingpin.Flag("timeout", "Time duration before canceling an ongoing probe such as 30m or 1h5m. This value must be at least 1m. Valid duration units are ns, us (or µs), ms, s, m, h.").Default("10m").String()
-	logLevel       = kingpin.Flag("log-level", "Printed logs level.").Default("debug").Enum("error", "warn", "info", "debug")
-	cacheRetention = kingpin.Flag("cache-retention", "Time duration to keep entries in cache such as 30m or 1h5m. Valid duration units are ns, us (or µs), ms, s, m, h.").Default("1h").String()
+	listenAddress     = kingpin.Flag("listen-address", "The address to listen on for HTTP requests.").Default(":19115").String()
+	probeTimeout      = kingpin.Flag("timeout", "Time duration before canceling an ongoing probe such as 30m or 1h5m. This value must be at least 1m. Valid duration units are ns, us (or µs), ms, s, m, h.").Default("10m").String()
+	logLevel          = kingpin.Flag("log-level", "Printed logs level.").Default("debug").Enum("error", "warn", "info", "debug")
+	cacheRetention    = kingpin.Flag("cache-retention", "Time duration to keep entries in cache such as 30m or 1h5m. Valid duration units are ns, us (or µs), ms, s, m, h.").Default("1h").String()
+	cacheIgnoreFailed = kingpin.Flag("cache-ignore-failed", "Do not cache failed results due to intermittent SSLLabs issues.").Default("False").Bool()
 
 	// build parameters
 	branch    string
@@ -78,6 +79,11 @@ func probeHandler(w http.ResponseWriter, r *http.Request, logger log.Logger, tim
 
 		registry = exporter.Handle(ctx, logger, target)
 
+		// do not cache failed assessments if configured
+		if *cacheIgnoreFailed && exporter.Failed(registry) {
+			return
+		}
+
 		// add the assessment results to the cache
 		resultsCache.add(target, registry)
 	}