#!/usr/bin/env python3

# load.py - PVC Monitoring example plugin for load
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018-2022 Joshua M. Boniface <joshua@boniface.me>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################

# This script provides an example of a PVC monitoring plugin script. It will create
# a simple plugin to check the system load against the total number of CPU cores,
# and return a 10 health delta (100 -> 90) if the load average is > 1/2 that number.

# This script can thus be used as an example or reference implementation of a
# PVC monitoring pluginscript and expanded upon as required.

# A monitoring plugin script must implement the class "MonitoringPluginScript" which
# extends "MonitoringPlugin", providing the 3 functions indicated. Detailed explanation
# of the role of each function is provided in context of the example; see the other
# examples for more potential uses.

# WARNING:
#
# This script will run in the context of the node daemon keepalives as root.
# DO NOT install untrusted, unvetted plugins under any circumstances.


# This import is always required here, as MonitoringPlugin is used by the
# MonitoringPluginScript class
from pvcnoded.objects.MonitoringInstance import MonitoringPlugin


# A monitoring plugin script must always expose its nice name, which must be identical to
# the file name
PLUGIN_NAME = "load"


# The MonitoringPluginScript class must be named as such, and extend MonitoringPlugin.
class MonitoringPluginScript(MonitoringPlugin):
    def setup(self):
        """
        setup(): Perform special setup steps during node daemon startup

        This step is optional and should be used sparingly.
        """

        pass

    def run(self):
        """
        run(): Perform the check actions and return a PluginResult object
        """

        # Run any imports first
        from os import getloadavg
        from psutil import cpu_count

        # Get the current 1-minute system load average
        load_average = getloadavg()[0]

        # Get the number of CPU cores
        cpu_cores = cpu_count()

        # Check that the load average is greater or equal to the cpu count
        if load_average > float(cpu_cores):
            # Set the health delta to 10 (subtract 10 from the total of 100)
            health_delta = 10
            # Craft a message that can be used by the clients
            message = f"Current load is {load_average} out of {cpu_cores} CPU cores"

        else:
            # Set the health delta to 0 (no change)
            health_delta = 0
            # Craft a message that can be used by the clients
            message = f"Current load is {load_average} out of {cpu_cores} CPU cores"

        # Set the health delta in our local PluginResult object
        self.plugin_result.set_health_delta(health_delta)

        # Set the message in our local PluginResult object
        self.plugin_result.set_message(message)

        # Return our local PluginResult object
        return self.plugin_result

    def cleanup(self):
        """
        cleanup(): Perform special cleanup steps during node daemon termination

        This step is optional and should be used sparingly.
        """

        pass