[receiver/hostmetrics] Continue scraping filesystem metric with parti…

…tions info available (open-telemetry#14734)

In case an error is returned while gathering partitions information, try to keep going if any subset of partitions was provided.

.chloggen/use_partitions_provided_if_possible.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: hostmetricsreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Allow to continue collecting partition information even if an error is returned
+
+# One or more tracking issues related to the change
+issues: [14315]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: Log the error and continue if partition information, however incomplete, was provided.

receiver/hostmetricsreceiver/internal/scraper/filesystemscraper/filesystem_scraper.go

@@ -78,11 +78,14 @@ func (s *scraper) scrape(_ context.Context) (pmetric.Metrics, error) {
 
 	// omit logical (virtual) filesystems (not relevant for windows)
 	partitions, err := s.partitions( /*all=*/ false)
+	var errors scrapererror.ScrapeErrors
 	if err != nil {
-		return pmetric.NewMetrics(), scrapererror.NewPartialScrapeError(err, metricsLen)
+		if len(partitions) == 0 {
+			return pmetric.NewMetrics(), scrapererror.NewPartialScrapeError(err, metricsLen)
+		}
+		errors.AddPartial(0, fmt.Errorf("failed collecting partitions information: %w", err))
 	}
 
-	var errors scrapererror.ScrapeErrors
 	usages := make([]*deviceUsage, 0, len(partitions))
 	for _, partition := range partitions {
 		if !s.fsFilter.includePartition(partition) {

receiver/hostmetricsreceiver/internal/scraper/filesystemscraper/filesystem_scraper_test.go

@@ -47,6 +47,8 @@ func TestScrape(t *testing.T) {
 		newErrRegex              string
 		initializationErr        string
 		expectedErr              string
+		failedMetricsLen         *int
+		continueOnErr            bool
 	}
 
 	testCases := []testCase{
@@ -200,6 +202,62 @@ func TestScrape(t *testing.T) {
 			partitionsFunc: func(bool) ([]disk.PartitionStat, error) { return nil, errors.New("err1") },
 			expectedErr:    "err1",
 		},
+		{
+			name: "Partitions and error provided",
+			config: Config{
+				Metrics: metadata.DefaultMetricsSettings(),
+				IncludeDevices: DeviceMatchConfig{
+					Config: filterset.Config{
+						MatchType: filterset.Strict,
+					},
+					Devices: []string{"device_a", "device_b"},
+				},
+				ExcludeFSTypes: FSTypeMatchConfig{
+					Config: filterset.Config{
+						MatchType: filterset.Strict,
+					},
+					FSTypes: []string{"fs_type_b"},
+				},
+			},
+			usageFunc: func(s string) (*disk.UsageStat, error) {
+				return &disk.UsageStat{
+					Fstype: "fs_type_a",
+				}, nil
+			},
+			partitionsFunc: func(b bool) ([]disk.PartitionStat, error) {
+				return []disk.PartitionStat{
+					{
+						Device:     "device_a",
+						Mountpoint: "mount_point_a",
+						Fstype:     "fs_type_a",
+					},
+					{
+						Device:     "device_b",
+						Mountpoint: "mount_point_d",
+						Fstype:     "fs_type_c",
+					},
+				}, errors.New("invalid partitions collection")
+			},
+			expectMetrics:            true,
+			expectedDeviceDataPoints: 2,
+			expectedDeviceAttributes: []map[string]pcommon.Value{
+				{
+					"device":     pcommon.NewValueStr("device_a"),
+					"mountpoint": pcommon.NewValueStr("mount_point_a"),
+					"type":       pcommon.NewValueStr("fs_type_a"),
+					"mode":       pcommon.NewValueStr("unknown"),
+				},
+				{
+					"device":     pcommon.NewValueStr("device_b"),
+					"mountpoint": pcommon.NewValueStr("mount_point_d"),
+					"type":       pcommon.NewValueStr("fs_type_c"),
+					"mode":       pcommon.NewValueStr("unknown"),
+				},
+			},
+			expectedErr:      "failed collecting partitions information: invalid partitions collection",
+			failedMetricsLen: new(int),
+			continueOnErr:    true,
+		},
 		{
 			name:        "Usage Error",
 			usageFunc:   func(string) (*disk.UsageStat, error) { return nil, errors.New("err2") },
@@ -243,12 +301,18 @@ func TestScrape(t *testing.T) {
 				if isPartial {
 					var scraperErr scrapererror.PartialScrapeError
 					require.ErrorAs(t, err, &scraperErr)
-					assert.Equal(t, metricsLen, scraperErr.Failed)
+					expectedFailedMetricsLen := metricsLen
+					if test.failedMetricsLen != nil {
+						expectedFailedMetricsLen = *test.failedMetricsLen
+					}
+					assert.Equal(t, expectedFailedMetricsLen, scraperErr.Failed)
 				}
-
-				return
+				if !test.continueOnErr {
+					return
+				}
+			} else {
+				require.NoError(t, err, "Failed to scrape metrics: %v", err)
 			}
-			require.NoError(t, err, "Failed to scrape metrics: %v", err)
 
 			if !test.expectMetrics {
 				assert.Equal(t, 0, md.MetricCount())