70 lines
4.5 KiB
Markdown
70 lines
4.5 KiB
Markdown
# 🚨 HEALTHCHECK
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A simple server health check.
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Allows to keep under control the machine vitals (cpu usage, raid status, thermals...) and alert the sysadmin in case of anomalies.
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Sends an email and/or executes a command in case of alarm.
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As an example, the command may be a ntfy call to obtain a notification on a mobile phone or desktop computer.
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Meant to be run with a cron (see healthcheck.cron.example).
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Tested on Debian 11, but should run on almost any standard linux box.
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## Alarms
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Provided ready-to-use alarms in config file:
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- cpu load
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- disk space
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- raid status
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- battery level / charger status (for laptops used as servers, apparently common among the self hosters)
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- memory status
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Alarms that need basic configuration to work on your system:
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- cpu temperature (needs to be adapted as every system has a different name for the sensor)
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- fan speed (needs to be adapted as every system has a different name for the sensor)
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... or you can write your own custom alarm!
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## How does it work
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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.
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Every check definition has:
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- DISABLED: boolean, wether to run the check
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- ALARM_VALUE_MORE_THAN: float, the alarm is issued if detected value exceeds the configured one
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- ALARM_VALUE_LESS_THAN: float, the alarm is issued if detected value is less than the configured one
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- ALARM_VALUE_EQUAL: float, the alarm is issued if detected value is equal to the configured one (the values are always compared as floats)
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- ALARM_VALUE_NOT_EQUAL: float, the alarm is issued if detected value is not equal to the configured one (the values are always compared as floats)
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- ALARM_STRING_EQUAL: string, the alarm is issued if detected value is equal to the configured one (the values are always compared as strings)
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- ALARM_STRING_NOT_EQUAL: string, the alarm is issued if detected value is not equal to the configured one (the values are always compared as strings)
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- COMMAND: the command to run to obtain the value
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- REGEXP: a regular expression that will be executed on the command output and returns a single group that will be compared with ALARM_*. If omitted, the complete command output will be used for comparation.
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## Installation
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Copy the script and the config file into the system to check:
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```
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cp healthcheck.py /usr/local/bin/healthcheck.py
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cp healthcheck.cfg.example /usr/local/etc/healthcheck.cfg
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```
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Make the script executable:
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```
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chmod +x /usr/local/bin/healthcheck.py
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```
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Edit `/usr/local/etc/healthcheck.cfg` enabling the checks you need and configuring email settings.
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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`.
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Now copy the cron file (it runs healthcheck every minute):
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```
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cp healthcheck.cron.example /etc/cron.d/healthcheck
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```
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For increased safety, edit the cron file placing your email address in MAILTO var to be notified in case of healthcheck.py catastrophic failure.
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Setup is now complete: the cron runs the script every minute and you will receive emails in case of failed checks.
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## Useful notes
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### Note on system load averages**:
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As stated in the `uptime` command manual:
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> System load averages is the average number of processes that are either in a runnable or uninterruptable state. A process in a runnable state is either using the CPU or waiting to use the CPU. A process in uninterruptable state is waiting for some I/O access, eg waiting for disk. The averages are taken over the three time intervals. Load averages are not normalized for the number of CPUs in a system, so a load average of 1 means a single CPU system is loaded all the time while on a 4 CPU system it means it was idle 75% of the time.
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### Note on temperature and fan speed checks:
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The check to run needs lm-sensors to be installed and configured. Check your distribution install guide.
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The sensors have different name in every system, so you WILL need to adapt the configuration.
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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...
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