Changes to add A records of source and registry as metrics

Changes to add A records of source and registry as metrics. The existing metrics -
external_dns_registry_endpoints_total & external_dns_source_endpoints_total gives a cumulative count of records all records (A, SRV, CNAME, TXT).

We have a metric - external_dns_controller_verified_records which gives the intersection of A records between source & regsitry. However, in order to determined how many records are yet to be synced to registry, we need count of total A records in registry & source.

controller/controller.go

@@ -94,6 +94,22 @@ var (
 			Help:      "Number of Source errors.",
 		},
 	)
+	registryARecords = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: "external_dns",
+			Subsystem: "registry",
+			Name:      "a_records",
+			Help:      "Number of Registry A records.",
+		},
+	)
+	sourceARecords = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: "external_dns",
+			Subsystem: "source",
+			Name:      "a_records",
+			Help:      "Number of Source A records.",
+		},
+	)
 	verifiedARecords = prometheus.NewGauge(
 		prometheus.GaugeOpts{
 			Namespace: "external_dns",
@@ -113,6 +129,8 @@ func init() {
 	prometheus.MustRegister(deprecatedRegistryErrors)
 	prometheus.MustRegister(deprecatedSourceErrors)
 	prometheus.MustRegister(controllerNoChangesTotal)
+	prometheus.MustRegister(registryARecords)
+	prometheus.MustRegister(sourceARecords)
 	prometheus.MustRegister(verifiedARecords)
 }
 
@@ -150,7 +168,8 @@ func (c *Controller) RunOnce(ctx context.Context) error {
 		return err
 	}
 	registryEndpointsTotal.Set(float64(len(records)))
-
+	regARecords := filterARecords(records)
+	registryARecords.Set(float64(len(regARecords)))
 	ctx = context.WithValue(ctx, provider.RecordsContextKey, records)
 
 	endpoints, err := c.Source.Endpoints(ctx)
@@ -160,6 +179,8 @@ func (c *Controller) RunOnce(ctx context.Context) error {
 		return err
 	}
 	sourceEndpointsTotal.Set(float64(len(endpoints)))
+	srcARecords := filterARecords(endpoints)
+	sourceARecords.Set(float64(len(srcARecords)))
 	vRecords := fetchMatchingARecords(endpoints, records)
 	verifiedARecords.Set(float64(len(vRecords)))
 	endpoints = c.Registry.AdjustEndpoints(endpoints)

controller/controller_test.go

@@ -470,3 +470,50 @@ func TestVerifyARecords(t *testing.T) {
 	)
 	assert.Equal(t, math.Float64bits(2), valueFromMetric(verifiedARecords))
 }
+
+func TestARecords(t *testing.T) {
+	testControllerFiltersDomains(
+		t,
+		[]*endpoint.Endpoint{
+			{
+				DNSName:    "record1.used.tld",
+				RecordType: endpoint.RecordTypeA,
+				Targets:    endpoint.Targets{"1.2.3.4"},
+			},
+			{
+				DNSName:    "record2.used.tld",
+				RecordType: endpoint.RecordTypeA,
+				Targets:    endpoint.Targets{"8.8.8.8"},
+			},
+			{
+				DNSName:    "_mysql-svc._tcp.mysql.used.tld",
+				RecordType: endpoint.RecordTypeSRV,
+				Targets:    endpoint.Targets{"0 50 30007 mysql.used.tld"},
+			},
+		},
+		endpoint.NewDomainFilter([]string{"used.tld"}),
+		[]*endpoint.Endpoint{
+			{
+				DNSName:    "record1.used.tld",
+				RecordType: endpoint.RecordTypeA,
+				Targets:    endpoint.Targets{"1.2.3.4"},
+			},
+			{
+				DNSName:    "_mysql-svc._tcp.mysql.used.tld",
+				RecordType: endpoint.RecordTypeSRV,
+				Targets:    endpoint.Targets{"0 50 30007 mysql.used.tld"},
+			},
+		},
+		[]*plan.Changes{{
+			Create: []*endpoint.Endpoint{
+				{
+					DNSName:    "record2.used.tld",
+					RecordType: endpoint.RecordTypeA,
+					Targets:    endpoint.Targets{"8.8.8.8"},
+				},
+			},
+		}},
+	)
+	assert.Equal(t, math.Float64bits(2), valueFromMetric(sourceARecords))
+	assert.Equal(t, math.Float64bits(1), valueFromMetric(registryARecords))
+}

docs/faq.md

@@ -187,6 +187,8 @@ Here is the full list of available metrics provided by ExternalDNS:
 | external_dns_source_errors_total                    | Number of Source errors                                 | Counter |
 | external_dns_controller_verified_records            | Number of DNS A-records that exists both in             | Gauge   |
 |                                                     | source & registry                                       |         |
+| external_dns_registry_a_records                     | Number of A records in registry                         | Gauge   |
+| external_dns_source_a_records                       | Number of A records in source                           | Gauge   |
 
 ### How can I run ExternalDNS under a specific GCP Service Account, e.g. to access DNS records in other projects?