Add TLS certs expiration metric

cmd/traefik/traefik.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"crypto/x509"
 	"encoding/json"
 	stdlog "log"
 	"net/http"
@@ -14,6 +15,7 @@ import (
 	"github.com/coreos/go-systemd/daemon"
 	assetfs "github.com/elazarl/go-bindata-assetfs"
 	"github.com/go-acme/lego/v4/challenge"
+	gokitmetrics "github.com/go-kit/kit/metrics"
 	"github.com/sirupsen/logrus"
 	"github.com/traefik/paerser/cli"
 	"github.com/traefik/traefik/v2/autogen/genstatic"
@@ -260,6 +262,11 @@ func setupServer(staticConfiguration *static.Configuration) (*server.Server, err
 	watcher.AddListener(func(conf dynamic.Configuration) {
 		ctx := context.Background()
 		tlsManager.UpdateConfigs(ctx, conf.TLS.Stores, conf.TLS.Options, conf.TLS.Certificates)
+
+		gauge := metricsRegistry.TLSCertsNotAfterTimestampGauge()
+		for _, certificate := range tlsManager.GetCertificates() {
+			appendCertMetric(gauge, certificate)
+		}
 	})
 
 	// Metrics
@@ -432,6 +439,20 @@ func registerMetricClients(metricsConfig *types.Metrics) []metrics.Registry {
 	return registries
 }
 
+func appendCertMetric(gauge gokitmetrics.Gauge, certificate *x509.Certificate) {
+	sort.Strings(certificate.DNSNames)
+
+	labels := []string{
+		"cn", certificate.Subject.CommonName,
+		"serial", certificate.SerialNumber.String(),
+		"sans", strings.Join(certificate.DNSNames, ","),
+	}
+
+	notAfter := float64(certificate.NotAfter.Unix())
+
+	gauge.With(labels...).Set(notAfter)
+}
+
 func setupAccessLog(conf *types.AccessLog) *accesslog.Handler {
 	if conf == nil {
 		return nil

cmd/traefik/traefik_test.go

@@ -0,0 +1,116 @@
+package main
+
+import (
+	"crypto/x509"
+	"encoding/pem"
+	"strings"
+	"testing"
+
+	"github.com/go-kit/kit/metrics"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// FooCert is a PEM-encoded TLS cert.
+// generated from src/crypto/tls:
+// go run generate_cert.go  --rsa-bits 1024 --host foo.org,foo.com  --ca --start-date "Jan 1 00:00:00 1970" --duration=1000000h
+const fooCert = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`
+
+// BarCert is a PEM-encoded TLS cert.
+// generated from src/crypto/tls:
+// go run generate_cert.go  --rsa-bits 1024 --host bar.org,bar.com  --ca --start-date "Jan 1 00:00:00 1970" --duration=10000h
+const barCert = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`
+
+type gaugeMock struct {
+	metrics map[string]float64
+	labels  string
+}
+
+func (g gaugeMock) With(labelValues ...string) metrics.Gauge {
+	g.labels = strings.Join(labelValues, ",")
+	return g
+}
+
+func (g gaugeMock) Set(value float64) {
+	g.metrics[g.labels] = value
+}
+
+func (g gaugeMock) Add(delta float64) {
+	panic("implement me")
+}
+
+func TestAppendCertMetric(t *testing.T) {
+	testCases := []struct {
+		desc     string
+		certs    []string
+		expected map[string]float64
+	}{
+		{
+			desc:     "No certs",
+			certs:    []string{},
+			expected: map[string]float64{},
+		},
+		{
+			desc:  "One cert",
+			certs: []string{fooCert},
+			expected: map[string]float64{
+				"cn,,serial,123624926713171615935660664614975025408,sans,foo.com,foo.org": 3.6e+09,
+			},
+		},
+		{
+			desc:  "Two certs",
+			certs: []string{fooCert, barCert},
+			expected: map[string]float64{
+				"cn,,serial,123624926713171615935660664614975025408,sans,foo.com,foo.org": 3.6e+09,
+				"cn,,serial,152706022658490889223053211416725817058,sans,bar.com,bar.org": 3.6e+07,
+			},
+		},
+	}
+
+	for _, test := range testCases {
+		test := test
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			gauge := &gaugeMock{
+				metrics: map[string]float64{},
+			}
+
+			for _, cert := range test.certs {
+				block, _ := pem.Decode([]byte(cert))
+				parsedCert, err := x509.ParseCertificate(block.Bytes)
+				require.NoError(t, err)
+
+				appendCertMetric(gauge, parsedCert)
+			}
+
+			assert.Equal(t, test.expected, gauge.metrics)
+		})
+	}
+}