Implemented alarm command

README.md

@@ -3,20 +3,27 @@ A collection of utilities for self hosters.
 
 ## HEALTHCHECK
 A simple server health check.
-Sends an email in case of alarm.
-Meant to be run with a cron (see healthcheck.cron.example)
-Tested on Debian 11, but should run on almost any standard linux box
+Sends an email and/or executes a command in case of alarm.
+As an example, the command may be a ntfy call to obtain a notification on a mobile phone or desktop computer.
+Meant to be run with a cron (see healthcheck.cron.example).
+Tested on Debian 11, but should run on almost any standard linux box.
+
+![Email](images/healthcheck_email_notification.png)      ![Ntfy](images/healthcheck_ntfy_notification.png)
 
 ### Alarms
 Provided ready-to-use alarms in config file:
-- system load
+- cpu load
 - disk space
 - raid status
 - battery level / charger status (for laptops used as servers, apparently common among the self hosters)
 - memory status
+
+Alarms that need basic configuration to work on your system:
 - cpu temperature (needs to be adapted as every system has a different name for the sensor)
 - fan speed (needs to be adapted as every system has a different name for the sensor)
 
+... or you can write your own custom alarm!
+
 ### How does it work
 The config file contains a list of checks. The most common checks are provided in the config file, but it is possible to configure custom checks, if needed.
 Every check definition has:
@@ -37,7 +44,7 @@ cp healthcheck.py /usr/local/bin/healthcheck.py
 cp healthcheck.cfg.example /usr/local/etc/healthcheck.cfg
 ```
 Edit `/usr/local/etc/healthcheck.cfg` enabling the checks you need and configuring email settings.
-Run `/usr/local/bin/healthcheck.py /usr/local/etc/healthcheck.cfg` to check it is working. If needed, change the config to make a check fail and see if the notification mail is delivered.
+Run `/usr/local/bin/healthcheck.py /usr/local/etc/healthcheck.cfg` to check it is working. If needed, change the config to make a check fail and see if the notification mail is delivered. If you need to do some testing without spamming emails, run with the parameter `--dry-run`.
 Now copy the cron file:
 ```
 cp healthcheck.cron.example /etc/cron.d/healthcheck
@@ -54,4 +61,7 @@ As stated in the `uptime` command manual:
 #### Note on temperature and fan speed checks:
 The check to run needs lm-sensors to be installed and configured. Check your distribution install guide.
 The sensors have different name in every system, so you WILL need to adapt the configuration.
+Some systems have a single temperature sensors for the whole CPU, while some other has a sensor for every core. In this last case, you may want to copy the `[cpu_temperature]` config in N different configs like `[cpu_temperature_0]`, one for every core, and change the REGEX to match `Core 0`, `Core 1` and so on...
 
+# License
+This whole repository is released under GNU General Public License version 3: see http://www.gnu.org/licenses/

healthcheck.cfg.example

@@ -1,12 +1,13 @@
 [DEFAULT]
 
-#### EMAIL NOTIFICATIONS
+#### EMAIL NOTIFICATIONS ####
 
 # Notify this email address(es) in case of alarm, multiple addresses separated by commas
+# Comment this if you don't want email to be sent (maybe because using ALARM_COMMAND below)
 MAILTO=root@localhost, user@localhost
 
 # Sender address
-MAILFROM=root@localhost
+#MAILFROM=root@localhost
 
 # Use a remote SMTP host (enable by removing comment)
 #SMTPHOST=my.smtp.host:465
@@ -19,6 +20,24 @@ MAILFROM=root@localhost
 #SMTPSSL=True
 
 
+#### RUN COMMAND IN CASE OF ALARM ####
+# You can run a command or script when an alert is issued.
+#
+# In this example, `curl` is used to send a POST request to Ntfy (https://ntfy.sh/), a service
+# that delivers push notifications to smartphones and desktop computers.
+# If you want to use ntfy, just change the topic name with something unique (see documentation
+# at https://ntfy.sh/docs/ ), uncomment the ALARM_COMMAND entry and you are ready to go.
+# If you generate a lot of traffic, please consider hosting your own ntfy server.
+#
+# Otherwise, you can replace the curl command with anything you want, you can use the following
+# placeholders to pass your command/script the details about the event:
+# %%CHECKNAME%% The name of the check (the one between square brackets in this config)
+# %%HOSTNAME%% The host name
+# %%DATETIME%% The date and time of the event, in human readable format
+# %%ERROR%% An human readable error description (the same used in the mail alert)
+
+#ALARM_COMMAND=curl -H "%%CHECKNAME%% alarm on %%HOSTNAME%%" -d "%%ERROR%% on %%DATETIME%%" ntfy.sh/my-unique-topic-name
+
 
 #### HEALTH CHECKS ####
 # Every health check is based on a command being executed, its result being parsed with a regexp
@@ -91,7 +110,7 @@ ALARM_VALUE_LESS_THAN=90
 DISABLED=True
 COMMAND=acpi -a
 REGEXP=Adapter \d: (.+)
-ALARM_STRING_NOT_EQUAL=on-line
+ALARM_STRING_EQUAL=off-line
 
 [free_ram]
 # Free ram in %

healthcheck.py

@@ -73,6 +73,7 @@ class Main:
 
 		self.config = configparser.ConfigParser(interpolation=None)	# Disable interpolation because contains regexp
 		self.config.read(configPath)
+		self.hostname = os.uname()[1]
 
 	def run(self, dryRun):
 		''' Runs the healtg checks '''
@@ -93,7 +94,10 @@ class Main:
 				# Alarm!
 				logging.warning('Alarm for {}: {}!'.format(section, error))
 				if not dryRun:
+					if s.mailto:
 						self.sendMail(s, error)
+					if s.alarmCommand:
+						self.executeAlarmCommand(s, error)
 
 	# Calls the provided command, checks the value parsing it with the provided regexp
 	# and returns an error string, or null if the value is within its limits
@@ -139,17 +143,15 @@ class Main:
 		if config.alarm_value_less_than and locale.atof(detectedValue) < float(config.alarm_value_less_than):
 			return 'value is {}, but should be greater than {}'.format(locale.atof(detectedValue), config.alarm_value_less_than)
 
-
 	def sendMail(self, s, error):
 		if s.smtphost:
-			logging.info("Sending detailed logs to %s via  %s", s.mailto, s.smtphost)
+			logging.info("Sending alarm email to %s via %s", s.mailto, s.smtphost)
 		else:
-			logging.info("Sending detailed logs to %s using local smtp", s.mailto)
+			logging.info("Sending alarm email to %s using local smtp", s.mailto)
 
 		# Create main message
-		hostname = os.uname()[1]
 		msg = MIMEMultipart()
-		msg['Subject'] = EMAIL_SUBJECT_TPL.format(hostname, s.name)
+		msg['Subject'] = EMAIL_SUBJECT_TPL.format(self.hostname, s.name)
 		if s.mailfrom:
 			m_from = s.mailfrom
 		else:
@@ -161,7 +163,7 @@ class Main:
 		# Add base text
 		body = EMAIL_MESSAGE_TPL.format(
 			s.name,
-			hostname,
+			self.hostname,
 			time.strftime("%a, %d %b %Y %H:%M:%S"),
 			error
 		)
@@ -183,6 +185,25 @@ class Main:
 		smtp.sendmail(m_from, s.mailto, msg.as_string())
 		smtp.quit()
 
+	def executeAlarmCommand(self, s, error):
+		cmdToRun = s.alarmCommand
+		cmdToRun = cmdToRun.replace('%%CHECKNAME%%', s.name)
+		cmdToRun = cmdToRun.replace('%%HOSTNAME%%', self.hostname)
+		cmdToRun = cmdToRun.replace('%%DATETIME%%', time.strftime("%a, %d %b %Y %H:%M:%S"))
+		cmdToRun = cmdToRun.replace('%%ERROR%%', error)
+
+		logging.debug("Executing alarm command %s", cmdToRun)
+
+		ret = subprocess.run(cmdToRun, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
+		if ret.stderr:
+			self._log.info('{} subprocess stderr:\n{}', cmdToRun, ret.stderr.decode())
+		if ret.stdout:
+			stdout = ret.stdout.decode()
+			self._log.debug('{} subprocess stdout:\n{}', cmdToRun, stdout)
+		if ret.returncode != 0:
+			self._log.error('subprocess {} exited with error code {}'.format(cmdToRun, ret.returncode))
+
+
 
 class Settings:
 	''' Represents settings for a check '''
@@ -203,9 +224,14 @@ class Settings:
 		self.smtpuser = self.getStr(name, 'SMTPUSER', None)
 		self.smtppass = self.getStr(name, 'SMTPPASS', None)
 		self.smtpssl = self.getBoolean(name, 'SMTPSSL', False)
-		## List of email address to notify about backup status (mandatory)
-		mailtoList = config.get(name, 'MAILTO')
+		## List of email address to notify in case of alarms (disabled if missing)
+		mailtoList = self.getStr(name, 'MAILTO', None)
+		if mailtoList:
 			self.mailto = [ x.strip() for x in mailtoList.strip().split(self.EMAIL_LIST_SEP) ]
+		else:
+			self.mailto = None
+		## Command to execute in case of alarms (disabled if missing)
+		self.alarmCommand = self.getStr(name, 'ALARM_COMMAND', None)
 		## Sender address for the notification email
 		self.mailfrom = self.getStr(name, 'MAILFROM', getpass.getuser()+'@'+socket.gethostname())
 		## Values to compare
@@ -233,6 +259,7 @@ class Settings:
 			return defaultValue
 
 
+
 if __name__ == '__main__':
 	import argparse