chore: class_fibrechannel: support optional attributes

Signed-off-by: machine424 <[email protected]>

Author: machine424

sysfs/class_fibrechannel.go

@@ -93,6 +93,11 @@ func (fs FS) parseFibreChannelHost(name string) (*FibreChannelHost, error) {
 		name := filepath.Join(path, f)
 		value, err := util.SysReadFile(name)
 		if err != nil {
+			// drivers can choose not to expose some attributes to sysfs.
+			// See: https://github.com/prometheus/node_exporter/issues/2919.
+			if os.IsNotExist(err)  {
+				continue
+			}
 			return nil, fmt.Errorf("failed to read file %q: %w", name, err)
 		}
 

sysfs/class_fibrechannel_test.go

@@ -64,6 +64,9 @@ func TestFibreChannelClass(t *testing.T) {
 				FCPPacketAborts:       0x13,
 			},
 		},
+		"host1": FibreChannelHost{
+			Name:             "host1",
+		},
 	}
 
 	if diff := cmp.Diff(want, got); diff != "" {

testdata/fixtures.ttar

@@ -5068,6 +5068,12 @@ Lines: 1
 Emulex SN1100E2P FV12.4.270.3 DV12.4.0.0. HN:gotest. OS:Linux
 Mode: 644
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/class/fc_host/host1
+Mode: 755
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/sys/class/fc_host/host1/statistics
+Mode: 755
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/sys/class/infiniband
 Mode: 755
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -