Merge branch 'smh-read-only-gauge' into 'master'

Export prometheus metric for read-only mode

See merge request gitlab-org/gitaly!2224

4 files changed, 22 insertions, 0 deletions

diff --git a/internal/praefect/metrics/prometheus.go b/internal/praefect/metrics/prometheus.go
index 808fedc1c..7db03bf7b 100644
--- a/internal/praefect/metrics/prometheus.go
+++ b/internal/praefect/metrics/prometheus.go
@@ -105,6 +105,13 @@ var PrimaryGauge = prometheus.NewGaugeVec(
 	}, []string{"virtual_storage", "gitaly_storage"},
 )
 
+var ReadOnlyGauge = prometheus.NewGaugeVec(
+	prometheus.GaugeOpts{
+		Name: "gitaly_praefect_read_only_mode",
+		Help: "Shows whether a virtual storage is in read-only mode.",
+	}, []string{"virtual_storage"},
+)
+
 var NodeLastHealthcheckGauge = prometheus.NewGaugeVec(
 	prometheus.GaugeOpts{
 		Namespace: "gitaly",
@@ -136,6 +143,7 @@ func init() {
 	prometheus.MustRegister(
 		MethodTypeCounter,
 		PrimaryGauge,
+		ReadOnlyGauge,
 		ChecksumMismatchCounter,
 		NodeLastHealthcheckGauge,
 		ReadDistribution,
diff --git a/internal/praefect/metrics/util.go b/internal/praefect/metrics/util.go
new file mode 100644
index 000000000..804804454
--- /dev/null
+++ b/internal/praefect/metrics/util.go
@@ -0,0 +1,11 @@
+package metrics
+
+// BoolAsFloat is a utility for converting a boolean value to a float64
+// for Prometheus. Returns 1 if bool is true, else 0.
+func BoolAsFloat(b bool) float64 {
+	if b {
+		return 1
+	}
+
+	return 0
+}
diff --git a/internal/praefect/nodes/local_elector.go b/internal/praefect/nodes/local_elector.go
index d0ddbd0a9..c46491437 100644
--- a/internal/praefect/nodes/local_elector.go
+++ b/internal/praefect/nodes/local_elector.go
@@ -125,6 +125,8 @@ func (s *localElector) checkNodes(ctx context.Context) error {
 	s.previousWritablePrimary = previousWritablePrimary
 	s.isReadOnly = s.readOnlyAfterFailover
 
+	metrics.ReadOnlyGauge.WithLabelValues(s.shardName).Set(metrics.BoolAsFloat(s.isReadOnly))
+
 	return nil
 }
 
diff --git a/internal/praefect/nodes/sql_elector.go b/internal/praefect/nodes/sql_elector.go
index 2ead9f7d6..38b74bbd2 100644
--- a/internal/praefect/nodes/sql_elector.go
+++ b/internal/praefect/nodes/sql_elector.go
@@ -546,6 +546,7 @@ func (s *sqlElector) lookupPrimary() (*sqlCandidate, bool, Node, error) {
 	var primaryNode *sqlCandidate
 	if primaryName != "" {
 		primaryNode = s.lookupNodeByName(primaryName)
+		metrics.ReadOnlyGauge.WithLabelValues(s.shardName).Set(metrics.BoolAsFloat(readOnly))
 	}
 
 	var prevWritablePrimary Node