enables scheduler metrics

this replaces prometheus client_golang default
collector with one that includes Go scheduler metrics

cmd/spicedb/main.go

@@ -14,6 +14,7 @@ import (
 	"github.com/authzed/spicedb/pkg/cmd"
 	cmdutil "github.com/authzed/spicedb/pkg/cmd/server"
 	"github.com/authzed/spicedb/pkg/cmd/testserver"
+	_ "github.com/authzed/spicedb/pkg/runtime"
 	"github.com/authzed/spicedb/pkg/spiceerrors"
 )
 

pkg/runtime/metrics.go

@@ -0,0 +1,17 @@
+package runtime
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+)
+
+// prometheus client_golang by default registers a collector that collects all metrics, except scheduler metrics
+// this package unregisters the default collector and adds one that includes scheduler metrics
+//
+// in order to register this, the package must be imported anonymously
+func init() {
+	prometheus.DefaultRegisterer.Unregister(collectors.NewGoCollector())
+	prometheus.MustRegister(collectors.NewGoCollector(
+		collectors.WithGoCollectorRuntimeMetrics(collectors.MetricsAll),
+	))
+}