Add email action for space trigger critical

docs/aoa/actions.rst

@@ -25,10 +25,40 @@ reached:
     [fs]
     warning=70
     warning_action=echo {{mnt_point}} {{used}}/{{size}} > /tmp/fs.alert
+    
+A last example would be to create a log file
+containing the total user disk space usage for a device and notify by email each time a space trigger critical is
+reached:
+    
+.. code-block:: ini
+
+    [fs]
+    critical=90
+    critical_action_repeat=echo {{device_name}} {{percent}} > /tmp/fs.alert && python /etc/glances/actions.d/fs-critical.py
+    
+Within ``/etc/glances/actions.d/fs-critical.py``:
+
+.. code-block:: python
+
+    import subprocess
+    from requests import get
+
+    fs_alert = open('/tmp/fs.alert', 'r').readline().strip().split(' ')
+    device = fs_alert[0]
+    percent = fs_alert[1]
+    system = subprocess.check_output(['uname', '-rn']).decode('utf-8').strip()
+    ip = get('https://api.ipify.org').text
+
+    body = 'Used user disk space for ' + device + ' is at ' + percent + '%.\nPlease cleanup the filesystem to clear the alert.\nServer: ' + str(system)+ '.\nIP address: ' + ip
+    ps = subprocess.Popen(('echo', '-e', body), stdout=subprocess.PIPE)
+    subprocess.call(['mail', '-s', 'CRITICAL: disk usage above 90%', '-r', 'postmaster@example.com', 'glances@example.com'], stdin=ps.stdout)
+
+
+
 
 .. note::
     You can use all the stats for the current plugin. See
-    https://github.com/nicolargo/glances/wiki/The-Glances-2.x-API-How-to
+    https://github.com/nicolargo/glances/wiki/The-Glances-RESTFULL-JSON-API
     for the stats list.
 
 It is also possible to repeat action until the end of the alert.