Fix daemon startup latency issue by providing an option to skip snaps…

…hotter supported flag

cmd/soci-snapshotter-grpc/main.go

@@ -125,8 +125,19 @@ func main() {
 		log.G(ctx).WithError(err).Fatal(err)
 	}
 
-	if err := service.Supported(*rootDir); err != nil {
-		log.G(ctx).WithError(err).Fatalf("snapshotter is not supported")
+	if !cfg.SkipCheckSnapshotterSupported {
+		if err := service.Supported(*rootDir); err != nil {
+			log.G(ctx).WithError(err).Fatalf("snapshotter is not supported")
+		}
+		log.G(ctx).WithFields(logrus.Fields{
+			"version":  version.Version,
+			"revision": version.Revision,
+		}).Debug("snapshotter is supported")
+	} else {
+		log.G(ctx).WithFields(logrus.Fields{
+			"version":  version.Version,
+			"revision": version.Revision,
+		}).Warn("Skipped snapshotter is supported check ")
 	}
 
 	// Create a gRPC server

config/fs.go

@@ -56,6 +56,7 @@ type FSConfig struct {
 	NoPrometheus                   bool   `toml:"no_prometheus"`
 	MountTimeoutSec                int64  `toml:"mount_timeout_sec"`
 	FuseMetricsEmitWaitDurationSec int64  `toml:"fuse_metrics_emit_wait_duration_sec"`
+	SkipCheckSnapshotterSupported  bool   `toml:"skip_check_snapshotter_supported"`
 
 	RetryableHTTPClientConfig `toml:"http"`
 	BlobConfig                `toml:"blob"`

docs/config.md

@@ -26,6 +26,7 @@ This set of variables must be at the top of your TOML file due to not belonging
 - `no_prometheus` (bool) — Toggle prometheus metrics. Default: false.
 - `mount_timeout_sec` (int) — Timeout for mount if a layer can't be resolved. Default: 30.
 - `fuse_metrics_emit_wait_duration_sec` (int) — The wait time before the snaphotter emits FUSE operation counts for an image. Default: 60.
+- `skip_check_snapshotter_supported` (bool) - skip check for snapshotter is supported which can give performance benefits for soci daemon startup time. This config to be done if you are sure overlayfs is supported. Default: false
 
 ## config/config.go
 ### Config