Add ca certificate metrics (#10504)

* add intermediate ca metric routine

* add Gauge config for intermediate cert

* Stop metrics routine when stopping leader

* add changelog entry

* updage changelog

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* use variables instead of a map

* go imports sort

* Add metrics for primary and secondary ca

* start metrics routine in the right DC

* add telemetry documentation

* update docs

* extract expiry fetching in a func

* merge metrics for primary and secondary into signing ca metric

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

.changelog/10504.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+telemetry: added metrics to track certificates expiry.
+```

agent/consul/leader_connect.go

@@ -37,6 +37,7 @@ func (s *Server) startConnectLeader(ctx context.Context) error {
 	s.caManager.Start(ctx)
 	s.leaderRoutineManager.Start(ctx, caRootPruningRoutineName, s.runCARootPruning)
 	s.leaderRoutineManager.Start(ctx, caRootMetricRoutineName, rootCAExpiryMonitor(s).monitor)
+	s.leaderRoutineManager.Start(ctx, caSigningMetricRoutineName, signingCAExpiryMonitor(s).monitor)
 
 	return s.startIntentionConfigEntryMigration(ctx)
 }
@@ -46,6 +47,8 @@ func (s *Server) stopConnectLeader() {
 	s.caManager.Stop()
 	s.leaderRoutineManager.Stop(intentionMigrationRoutineName)
 	s.leaderRoutineManager.Stop(caRootPruningRoutineName)
+	s.leaderRoutineManager.Stop(caRootMetricRoutineName)
+	s.leaderRoutineManager.Stop(caSigningMetricRoutineName)
 
 	// If the provider implements NeedsStop, we call Stop to perform any shutdown actions.
 	provider, _ := s.caManager.getCAProvider()

agent/consul/leader_metrics.go

@@ -2,25 +2,34 @@ package consul
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
+	"github.com/hashicorp/consul/agent/connect/ca"
+
+	"github.com/hashicorp/consul/agent/connect"
+
 	"github.com/armon/go-metrics"
 	"github.com/armon/go-metrics/prometheus"
-	"github.com/hashicorp/go-hclog"
-
 	"github.com/hashicorp/consul/logging"
+	"github.com/hashicorp/go-hclog"
 )
 
+var metricsKeyMeshRootCAExpiry = []string{"mesh", "active-root-ca", "expiry"}
+var metricsKeyMeshActiveSigningCAExpiry = []string{"mesh", "active-signing-ca", "expiry"}
+
 var CertExpirationGauges = []prometheus.GaugeDefinition{
 	{
 		Name: metricsKeyMeshRootCAExpiry,
-		Help: "Seconds until the service mesh root certificate expires.",
+		Help: "Seconds until the service mesh root certificate expires. Updated every hour",
+	},
+	{
+		Name: metricsKeyMeshActiveSigningCAExpiry,
+		Help: "Seconds until the service mesh signing certificate expires. Updated every hour",
 	},
 }
 
-var metricsKeyMeshRootCAExpiry = []string{"mesh", "active-root-ca", "expiry"}
-
 func rootCAExpiryMonitor(s *Server) certExpirationMonitor {
 	return certExpirationMonitor{
 		Key: metricsKeyMeshRootCAExpiry,
@@ -29,6 +38,12 @@ func rootCAExpiryMonitor(s *Server) certExpirationMonitor {
 		},
 		Logger: s.logger.Named(logging.Connect),
 		Query: func() (time.Duration, error) {
+			return getRootCAExpiry(s)
+		},
+	}
+}
+
+func getRootCAExpiry(s *Server) (time.Duration, error) {
 	state := s.fsm.State()
 	_, root, err := state.CARootActive(nil)
 	switch {
@@ -39,8 +54,59 @@ func rootCAExpiryMonitor(s *Server) certExpirationMonitor {
 	}
 
 	return time.Until(root.NotAfter), nil
+}
+
+func signingCAExpiryMonitor(s *Server) certExpirationMonitor {
+	isPrimary := s.config.Datacenter == s.config.PrimaryDatacenter
+	if isPrimary {
+		return certExpirationMonitor{
+			Key: metricsKeyMeshActiveSigningCAExpiry,
+			Labels: []metrics.Label{
+				{Name: "datacenter", Value: s.config.Datacenter},
+			},
+			Logger: s.logger.Named(logging.Connect),
+			Query: func() (time.Duration, error) {
+				provider, _ := s.caManager.getCAProvider()
+
+				if _, ok := provider.(ca.PrimaryUsesIntermediate); !ok {
+					return getActiveIntermediateExpiry(s)
+				}
+
+				return getRootCAExpiry(s)
+
 			},
 		}
+	} else {
+		return certExpirationMonitor{
+			Key: metricsKeyMeshActiveSigningCAExpiry,
+			Labels: []metrics.Label{
+				{Name: "datacenter", Value: s.config.Datacenter},
+			},
+			Logger: s.logger.Named(logging.Connect),
+			Query: func() (time.Duration, error) {
+				return getActiveIntermediateExpiry(s)
+			},
+		}
+	}
+}
+
+func getActiveIntermediateExpiry(s *Server) (time.Duration, error) {
+	state := s.fsm.State()
+	_, root, err := state.CARootActive(nil)
+	if err != nil {
+		return 0, err
+	}
+
+	// the CA used in a secondary DC is the active intermediate,
+	// which is the last in the IntermediateCerts stack
+	if len(root.IntermediateCerts) == 0 {
+		return 0, errors.New("no intermediate available")
+	}
+	cert, err := connect.ParseCert(root.IntermediateCerts[len(root.IntermediateCerts)-1])
+	if err != nil {
+		return 0, err
+	}
+	return time.Until(cert.NotAfter), nil
 }
 
 type certExpirationMonitor struct {

agent/consul/server.go

@@ -103,6 +103,7 @@ const (
 	aclUpgradeRoutineName                 = "legacy ACL token upgrade"
 	caRootPruningRoutineName              = "CA root pruning"
 	caRootMetricRoutineName               = "CA root expiration metric"
+	caSigningMetricRoutineName            = "CA signing expiration metric"
 	configReplicationRoutineName          = "config entry replication"
 	federationStateReplicationRoutineName = "federation state replication"
 	federationStateAntiEntropyRoutineName = "federation state anti-entropy"

website/content/docs/agent/telemetry.mdx

@@ -479,6 +479,7 @@ These metrics give insight into the health of the cluster as a whole.
 | `consul.catalog.connect.query-tags..` | Increments for each connect-based catalog query for the given service with the given tags.                                                                                                                                                                                                                                                                                                                                                | queries                                 | counter |
 | `consul.catalog.connect.not-found.`   | Increments for each connect-based catalog query where the given service could not be found.                                                                                                                                                                                                                                                                                                                                               | queries                                 | counter |
 | `consul.mesh.active-root-ca.expiry`    | The number of seconds until the root CA expires, updated every hour. | seconds | gauge |
+| `consul.mesh.active-signing-ca.expiry` | The number of seconds until the signing CA expires, updated every hour.                                                                                                                                                                                                                                                                                                                                                            | seconds                                 | gauge   |
 
 ## Connect Built-in Proxy Metrics