feat: added span gauge to prometheus (#36)

Author: robbert229

.devcontainer/devcontainer.json

@@ -7,6 +7,7 @@
 	// Features to add to the dev container. More info: https://containers.dev/features.
 	"features": {
 		"ghcr.io/robbert229/devcontainer-features/operator-sdk:latest": {},
+		"ghcr.io/robbert229/devcontainer-features/postgresql-client:1": {},
 		"ghcr.io/rio/features/k3d:latest": {},
 		"ghcr.io/rio/features/k9s:1.1.5": {},
 		"ghcr.io/devcontainers/features/docker-outside-of-docker:1": {},

Makefile

@@ -10,12 +10,12 @@ publish:
 
 # plugin-start starts Jaeger-PostgreSQL
 .PHONY: plugin-start
-run-plugin:
+plugin-start:
 	go run ./cmd/jaeger-postgresql -database.url=$(DBSTRING) -log-level=debug
 
 # jaeger-start starts the all-in-one jaeger.
 .PHONY: jaeger-start
-run-jaeger:
+jaeger-start:
 	SPAN_STORAGE_TYPE='grpc-plugin' ./hack/jaeger-all-in-one --grpc-storage.server='127.0.0.1:12345' --query.enable-tracing=false
 
 .PHONY: install-all-in-one
@@ -63,7 +63,7 @@ migrate-status: install-goose
 .PHONY: tracegen-start
 tracegen-start:
 	docker run --rm --name jaeger-postgresql-tracegen --net=host \
-		jaegertracing/jaeger-tracegen:1.55 -traces=1000000
+		jaegertracing/jaeger-tracegen:1.55 -traces=1000
 
 # tracegen-stop stops the jaeger-tracegen test data producer.
 .PHONY: tracegen-stop

cmd/jaeger-postgresql/main.go

@@ -219,6 +219,12 @@ var (
 		Name:      "spans_table_bytes",
 		Help:      "The size of the spans table in bytes",
 	})
+
+	spansGuage = promauto.NewGauge(prometheus.GaugeOpts{
+		Namespace: "jaeger_postgresql",
+		Name:      "spans_count",
+		Help:      "The number of spans",
+	})
 )
 
 func main() {
@@ -259,9 +265,17 @@ func main() {
 						if err != nil {
 							logger.Error("failed to query for disk size", "err", err)
 							continue
+						} else {
+							spansTableDiskSizeGuage.Set(float64(byteCount))
 						}
 
-						spansTableDiskSizeGuage.Set(float64(byteCount))
+						count, err := q.GetSpansCount(ctx)
+						if err != nil {
+							logger.Error("failed to query for span count", "err", err)
+							continue
+						} else {
+							spansGuage.Set(float64(count))
+						}
 
 					}
 				}