registry/storage/driver: add test call to Stat on "/"

Stat(ctx, "/") is called by the registry healthcheck.
Also fixes blob name building in the Azure driver so it no longer
returns empty blob names. This was causing errors in the healthcheck
call to Stat for Azure.

Signed-off-by: Flavian Missi <fmissi@redhat.com>

registry/storage/driver/azure/azure.go

@@ -63,7 +63,8 @@ func New(params *Parameters) (*Driver, error) {
 	d := &driver{
 		azClient:      azClient,
 		client:        client,
-		rootDirectory: params.RootDirectory}
+		rootDirectory: params.RootDirectory,
+	}
 	return &Driver{baseEmbed: baseEmbed{Base: base.Base{StorageDriver: d}}}, nil
 }
 
@@ -420,6 +421,13 @@ func (d *driver) listBlobs(ctx context.Context, virtPath string) ([]string, erro
 }
 
 func (d *driver) blobName(path string) string {
+	// avoid returning an empty blob name.
+	// this will happen when rootDirectory is unset, and path == "/",
+	// which is what we get from the storage driver health check Stat call.
+	if d.rootDirectory == "" && path == "/" {
+		return path
+	}
+
 	return strings.TrimLeft(strings.TrimRight(d.rootDirectory, "/")+path, "/")
 }
 

registry/storage/driver/testsuites/testsuites.go

@@ -824,6 +824,15 @@ func (suite *DriverSuite) TestStatCall(c *check.C) {
 	c.Assert(fi.Path(), check.Equals, dirPath)
 	c.Assert(fi.Size(), check.Equals, int64(0))
 	c.Assert(fi.IsDir(), check.Equals, true)
+
+	// The storage healthcheck performs this exact call to Stat.
+	// PathNotFoundErrors are not considered health check failures.
+	_, err = suite.StorageDriver.Stat(suite.ctx, "/")
+	// Some drivers will return a not found here, while others will not
+	// return an error at all. If we get an error, ensure it's a not found.
+	if err != nil {
+		c.Assert(err, check.FitsTypeOf, storagedriver.PathNotFoundError{})
+	}
 }
 
 // TestPutContentMultipleTimes checks that if storage driver can overwrite the content