Add option to lowercase "device" tag

disk/assets/configuration/spec.yaml

@@ -200,7 +200,7 @@ files:
               Works on Linux only.
             value:
               example: false
-              type: boolean          
+              type: boolean
           - name: device_tag_re
             description: |
               Instruct the check to apply additional tags to matching
@@ -263,3 +263,13 @@ files:
                   type: string
                 - name: type
                   type: string
+
+          - name:  lowercase_device_tag
+            description: |
+              Enable this to lowercase the "device" tags for both partition and disk metrics.
+              This is useful only in very specific circumstances:
+                1. Your "device" tag is value is uppercase and your host is running on Linux.
+                2. You cannot use the "device_name" tag.
+            value:
+              type: boolean
+              example: false

disk/changelog.d/19964.added

@@ -0,0 +1 @@
+Add option to lowercase "device" tag. Useful for those who cannot use the "device_name" tag and need "device" to only be lowercase.

disk/datadog_checks/disk/config_models/defaults.py

@@ -24,6 +24,10 @@ def instance_include_all_devices():
     return True
 
 
+def instance_lowercase_device_tag():
+    return False
+
+
 def instance_min_collection_interval():
     return 15
 

disk/datadog_checks/disk/config_models/instance.py

@@ -59,6 +59,7 @@ class InstanceConfig(BaseModel):
     file_system_exclude: Optional[tuple[str, ...]] = None
     file_system_include: Optional[tuple[str, ...]] = None
     include_all_devices: Optional[bool] = None
+    lowercase_device_tag: Optional[bool] = None
     metric_patterns: Optional[MetricPatterns] = None
     min_collection_interval: Optional[float] = None
     min_disk_size: Optional[float] = None

disk/datadog_checks/disk/data/conf.yaml.default

@@ -252,3 +252,11 @@ instances:
     #     host: nfsserver
     #     share: /mnt/nfs_share
     #     type: nfs
+
+    ## @param lowercase_device_tag - boolean - optional - default: false
+    ## Enable this to lowercase the "device" tags for both partition and disk metrics.
+    ## This is useful only in very specific circumstances:
+    ##   1. Your "device" tag is value is uppercase and your host is running on Linux.
+    ##   2. You cannot use the "device_name" tag.
+    #
+    # lowercase_device_tag: false

disk/datadog_checks/disk/disk.py

@@ -65,6 +65,7 @@ def __init__(self, name, init_config, instances):
         self._compile_pattern_filters(instance)
         self._compile_tag_re()
         self._blkid_label_re = re.compile('LABEL=\"(.*?)\"', re.I)
+        self._lowercase_device_tag = is_affirmative(instance.get('lowercase_device_tag', False))
 
         if self._use_lsblk and self._blkid_cache_file:
             raise ConfigurationError("Only one of 'use_lsblk' and 'blkid_cache_file' can be set at the same time.")
@@ -183,7 +184,7 @@ def _get_tags(self, part):
         if Platform.is_win32():
             device_name = device_name.strip('\\').lower()
 
-        tags.append('device:{}'.format(device_name))
+        tags.append('device:{}'.format(device_name.lower() if self._lowercase_device_tag else device_name))
         tags.append('device_name:{}'.format(_base_device_name(part.device)))
         return tags
 
@@ -331,7 +332,7 @@ def collect_latency_metrics(self):
                 device_specific_tags = self._get_device_specific_tags(disk_name)
                 metric_tags.extend(device_specific_tags)
 
-                metric_tags.append('device:{}'.format(disk_name))
+                metric_tags.append('device:{}'.format(disk_name.lower() if self._lowercase_device_tag else disk_name))
                 metric_tags.append('device_name:{}'.format(_base_device_name(disk_name)))
                 if self.devices_label.get(disk_name):
                     metric_tags.extend(self.devices_label.get(disk_name))

disk/tests/test_unit.py

@@ -10,7 +10,7 @@
 
 from datadog_checks.base.utils.platform import Platform
 from datadog_checks.base.utils.timeout import TimeoutException
-from datadog_checks.dev.testing import requires_windows
+from datadog_checks.dev.testing import requires_windows, requires_linux
 from datadog_checks.dev.utils import ON_WINDOWS, get_metadata_metrics, mock_context_manager
 from datadog_checks.disk import Disk
 from datadog_checks.disk.disk import IGNORE_CASE
@@ -223,6 +223,60 @@ def test_use_mount(aggregator, instance_basic_mount, gauge_metrics, rate_metrics
     aggregator.assert_metrics_using_metadata(get_metadata_metrics())
 
 
+@requires_linux # Only linux cares about upper/lower case for paths.
+@pytest.mark.parametrize(
+    'lc_device_tag, expected_dev_path',
+    [
+        pytest.param(None, '//CIFS/DEV1', id='Default behavior, keep case'),
+        pytest.param(False, '//CIFS/DEV1', id='Disabled, keep case'),
+        pytest.param(True, '//cifs/dev1', id='Enabled, lowercase'),
+    ],
+)
+def test_lowercase_device_tag(
+    aggregator,
+    instance_basic_volume,
+    gauge_metrics,
+    rate_metrics,
+    count_metrics,
+    dd_run_check,
+    mocker,
+    lc_device_tag,
+    expected_dev_path,
+):
+    """
+    If explicitly configured, we will lowercase the "device" tag value.
+
+    For metrics with uppercase "device" tag values, our backend introduces a lowercase version of the tag.
+    Some customers don't like this and cannot use the "device_name" tag instead.
+    They requested that we add a switch for them to lowercase the "device" tag before we submit it.
+    This flag MUST be off by default to avoid breaking anyone else.
+    """
+    if lc_device_tag is not None:
+        instance_basic_volume['lowercase_device_tag'] = lc_device_tag
+    c = Disk('disk', {}, [instance_basic_volume])
+
+    if ON_WINDOWS:
+        mock_statvfs = mock_context_manager()
+    else:
+        mock_statvfs = mock.patch('os.statvfs', return_value=MockInodesMetrics(), __name__='statvfs')
+
+    full_dev_path = '//CIFS/DEV1'
+    mocker.patch(
+        'psutil.disk_partitions',
+        return_value=[MockPart(device=full_dev_path, fstype="cifs")],
+        __name__='disk_partitions',
+    )
+    mocker.patch('psutil.disk_usage', return_value=MockDiskMetrics(), __name__='disk_usage')
+    mocker.patch('psutil.disk_io_counters', return_value=MockDiskIOMetrics(full_dev_path))
+    with mock_statvfs:
+        dd_run_check(c)
+
+    for name in chain(gauge_metrics, rate_metrics, count_metrics):
+        aggregator.assert_metric_has_tag(name, f'device:{expected_dev_path}')
+        # Make sure the "device_name" tag isn't affected.
+        aggregator.assert_metric_has_tag(name, 'device_name:DEV1')
+
+
 @pytest.mark.usefixtures('psutil_mocks')
 def test_device_tagging(aggregator, gauge_metrics, rate_metrics, count_metrics, dd_run_check):
     instance = {