collectors: add mount point check

collectors/python.d.plugin/mount_point_check/README.md

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+# Mount Point Availability Monitoring with Netdata
+
+Monitors mount point availability.
+
+Following charts are drawn per host:
+
+1. **Status** boolean
+
+    - 1 if directory exists and is a mount point. 0 otherwise.
+
+## Configuration
+
+Edit the `python.d/mount_point_check.conf` configuration file using `edit-config` from the Netdata [config
+directory](https://learn.netdata.cloud/docs/configure/nodes), which is typically at `/etc/netdata`.
+
+```bash
+cd /etc/netdata   # Replace this path with your Netdata config directory, if different
+sudo ./edit-config python.d/mount_point_check.conf
+```
+
+```yaml
+jobs:
+  - name: _mnt_shared_blob_                 # [required] my job name
+    path: "/mnt/shared/blob/"               # [required] path to the mount point
+
+  - name: _var_lib_netdata_testmount_       # job name of second job
+    path: "/var/lib/netdata/testmount/"     # path to another mount point
+```
+
+## Alarms
+
+Edit the `health.d/mount_point_check.conf` configuration file using `edit-config` from the Netdata [config
+directory](https://learn.netdata.cloud/docs/configure/nodes), which is typically at `/etc/netdata`. The following
+example will send a critical alert as soon as one of the configured mount points is missing:
+
+```yaml
+ template: mount_point_missing
+       on: mountpointcheck.status
+    class: Errors
+     type: Other
+   lookup: max -1s of available
+    every: 10s
+    units: boolean
+     crit: $this <= 0
+  summary: Check whether the expected mount point is available.
+       to: sysadmin
+```
+
+### Notes
+
+- Filesystem permissions might block Netdata's access to the provided path in the configuration file. In this case the
+  state will be reported as 0.
+
+---
+
+

collectors/python.d.plugin/mount_point_check/mount_point_check.chart.py

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+# -*- coding: utf-8 -*-
+# Description: mount point check netdata python.d module
+
+import os
+
+from bases.FrameworkServices.ExecutableService import ExecutableService
+
+MOUNTPOINT_COMMAND = 'mountpoint /'
+
+ORDER = []
+
+CHARTS = {}
+
+
+class Service(ExecutableService):
+    def __init__(self, configuration=None, name=None):
+        ExecutableService.__init__(self, configuration=configuration, name=name)
+        self.configuration = configuration
+        self._create_order_and_charts()
+        self.order = ORDER
+        self.definitions = CHARTS
+        self.command = MOUNTPOINT_COMMAND
+
+    def _create_order_and_charts(self):
+        for job in self.configuration.get("jobs"):
+            if job.get("name") in CHARTS:
+                continue
+            ORDER.append(job.get("name"))
+            CHARTS[job.get("name")] = {
+                "options": [None, "Mount Point Check Status", "boolean", "status", "mountpointcheck.status", "line"],
+                "lines": [[f"{job.get('name')}.available", "available"]]}
+
+    def _get_data(self):
+        data = dict()
+        try:
+            for job in self.configuration.get("jobs"):
+                self.command[1] = job.get("path")
+                if os.path.exists(job.get("path")) and (
+                        self._get_raw_data()[0] == f"{job.get('path')} is a mountpoint\n"):
+                    data[f"{job.get('name')}.available"] = 1
+                else:
+                    data[f"{job.get('name')}.available"] = 0
+            return data
+        except (ValueError, AttributeError):
+            return None

collectors/python.d.plugin/mount_point_check/mount_point_check.conf

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+# netdata python.d.plugin configuration for mount_point_check
+#
+# This file is in YaML format. Generally the format is:
+#
+# name: value
+#
+# ----------------------------------------------------------------------
+# Global Variables
+# These variables set the defaults for all JOBs, however each JOB
+# may define its own, overriding the defaults.
+
+# update_every sets the default data collection frequency.
+# If unset, the python.d.plugin default is used.
+# update_every: 10
+
+# priority controls the order of charts at the netdata dashboard.
+# Lower numbers move the charts towards the top of the page.
+# If unset, the default for python.d.plugin is used.
+# priority: 60000
+
+# retries sets the number of retries to be made in case of failures.
+# If unset, the default for python.d.plugin is used.
+# Attempts to restore the service are made once every update_every
+# and only if the module has collected values in the past.
+# retries: 60
+
+# autodetection_retry sets the job re-check interval in seconds.
+# The job is not deleted if check fails.
+# Attempts to start the job are made once every autodetection_retry.
+# This feature is disabled by default.
+# autodetection_retry: 0
+#
+# ----------------------------------------------------------------------
+# MountPointCheck-specific variables
+#
+# jobs:
+#  - name: _mnt_shared_blob_                      # [required] my job name
+#    path: "/mnt/shared/blob/"                    # [required] path to the mount point
+
+#  - name: _var_lib_netdata_testmount_            # job name of second job
+#    path: "/var/lib/netdata/testmount/"          # path to another mount point