[disk] Improve denylisting messages and defaults

Author: mx-psi

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

@@ -44,12 +44,19 @@ instances:
     ## start matching from the beginning and therefore to match anywhere you
     ## must prepend `.*`. For exact matches append `$`.
     ##
+    ## Some Linux kernel RAM-based filesystems are included here by default;
+    ## remove them and adjust permissions if you want to keep track of them.
+    ##
+    ## Add the 'overlay' filesystem here to ignore Docker volumes on the host.
+    ##
     ## When conflicts arise, this will override `file_system_whitelist`.
     #
-    # file_system_blacklist:
-    #   - tmpfs$
-    #   - rootfs$
-    #   - autofs$
+    file_system_blacklist:
+      - configfs$
+      - debugfs$
+      - securityfs$
+      - sysfs$
+      - tracefs$
 
     ## @param device_whitelist - list of strings - optional
     ## Instruct the check to only collect from matching devices.
@@ -83,7 +90,7 @@ instances:
     ## anywhere you must prepend `.*`. For exact matches append `$`.
     #
     # mount_point_whitelist:
-    #   - /dev/sda[1-3]
+    #   - /mnt/device
     #   - 'C:'
 
     ## @param mount_point_blacklist - list of strings - optional

disk/datadog_checks/disk/disk.py

@@ -88,7 +88,12 @@ def check(self, instance):
                 )
                 continue
             except Exception as e:
-                self.log.warning('Unable to get disk metrics for %s: %s', part.mountpoint, e)
+                self.log.warning(
+                    u'Unable to get disk metrics for %s: %s. '
+                    u'You can exclude this mountpoint in the settings if it is invalid.',
+                    part.mountpoint,
+                    e,
+                )
                 continue
 
             # Exclude disks with size less than min_disk_size
@@ -147,7 +152,6 @@ def _exclude_disk(self, device, file_system, mount_point):
         """
         Return True for disks we don't want or that match regex in the config file
         """
-        self.log.debug('_exclude_disk: %s, %s, %s', device, file_system, mount_point)
 
         if not device or device == 'none':
             device = None
@@ -245,7 +249,12 @@ def _collect_inodes_metrics(self, mountpoint):
             )
             return metrics
         except Exception as e:
-            self.log.warning('Unable to get disk metrics for %s: %s', mountpoint, e)
+            self.log.warning(
+                u'Unable to get disk metrics for %s: %s. '
+                u'You can exclude this mountpoint in the settings if it is invalid.',
+                mountpoint,
+                e,
+            )
             return metrics
 
         if inodes.f_files != 0: