Mackerelのメトリック監視に合わせてメモリーを数値化する

check_memory.php

<?php
/**
* [plugin.checks.check_memory]
* command = "php /usr/local/bin/check_memory.php -c 90"
* max_check_attempts = 5
* check_interval = 1
* action = { command = "/etc/init.d/httpd graceful" }
* memo = "httpdによってmemoryが圧迫されたらhttpdをgracefulする"
**/

$check_option = get_check_option_int();

// $meminfo = get_test_data();
$meminfo = `cat /proc/meminfo`;

if (empty($meminfo)) {
    echo "Empty meminfo." . PHP_EOL ;
    exit(2);
}

$percent_used = get_percent_used_memory($meminfo);

check($percent_used, $check_option);

function check($percent_used, $check_option)
{
    if ($percent_used >= $check_option) {
        echo "Critical {$check_option}% over, Server {$percent_used}% used." . PHP_EOL;
        exit(2);
    }
}

function get_check_option_int()
{
    // -c hoge or --critical hoge
    $check_option = getopt("c:", ["critical:"]);

    if (empty($check_option)) {
        echo "Empty option" . PHP_EOL;
        exit(2);
    }

    $option = (int)$check_option["c"] ?? (int)$check_option["critical"];

    return $option;
}

function get_percent_used_memory($meminfo)
{
    $meminfo_array = explode("\n", $meminfo);

    /**
     * https://github.com/mackerelio/mackerel-agent/blob/master/metrics/linux/memory.go
     * Metrics "used" is calculated here like (total - available) for ease.
     */

    $meminfo_total = $meminfo_array[0];
    $meminfo_available = $meminfo_array[2];

    $total = get_parse_value($meminfo_total);
    $available = get_parse_value($meminfo_available);

    $used = $total - $available;
    $percent_used = $used / $total * 100;
    return (int)$percent_used;
}


function get_parse_value($meminfo_value)
{
    $meminfo_value_parse_array = array_filter(explode(' ', $meminfo_value));
    //使ってない
    $name = array_shift($meminfo_value_parse_array);
    $value = array_shift($meminfo_value_parse_array);

    return (int)$value;
}

/**
 * cat /proc/meminfo
 * @return string
 */
function get_test_data()
{

    $input = <<<EOF
MemTotal:        3980400 kB
MemFree:         2161708 kB
MemAvailable:    2732460 kB
Buffers:          142300 kB
Cached:           367132 kB
SwapCached:         2128 kB
Active:          1061712 kB
Inactive:         253028 kB
Active(anon):     769028 kB
Inactive(anon):    58324 kB
Active(file):     292684 kB
Inactive(file):   194704 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:        524284 kB
SwapFree:         509948 kB
Dirty:              1452 kB
Writeback:             0 kB
AnonPages:        803420 kB
Mapped:            68868 kB
Shmem:             22044 kB
Slab:             414952 kB
SReclaimable:     372636 kB
SUnreclaim:        42316 kB
KernelStack:        9392 kB
PageTables:        46416 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     2514484 kB
Committed_AS:    5428708 kB
VmallocTotal:   34359738367 kB
VmallocUsed:           0 kB
VmallocChunk:          0 kB
AnonHugePages:    204800 kB
ShmemHugePages:        0 kB
ShmemPmdMapped:        0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:       67560 kB
DirectMap2M:     3016704 kB
DirectMap1G:     1048576 kB
EOF;

    return $input;
}