Delete log files so that total size of all log files is kept within certain size limit.

log-killer.php

#!/usr/bin/env php
<?php
/* This script is designed to delete logs files if it exceeds a defined size limit.
 * Size limit is applied to all log files, instead of individual file.
 * The logs are sorted by filename in reversed alphabetical order.
 * Each file's size is counted and sum with previous file. If size limit is exceeded,
 * subsequent files are deleted.
 */

const MB = 1024 * 1024;

/** CONFIGURATIONS **/

/* State your configurations here.
 * - limit: Size in bytes.
 * - path: Absolute path to folder containing log files.
 * - prefix: Log filename prefix.
 */
$logs = [
	['limit' => 700 * MB, 'path' => '/path/to/application/logs', 'prefix' => 'log-'],
	['limit' => 100 * MB, 'path' => '/path/to/another/log', 'prefix' => 'example-'],
];

/** CODE **/

/**
 * Send message to STDOUT.
 * @param string $message
 */
function logInfo($message) {
	fwrite(STDOUT, date('Y-m-d H:i:s')." {$message}".PHP_EOL);
}

/**
 * Send message to STDERR
 * @param string $message
 */
function logError($message) {
	fwrite(STDERR, date('Y-m-d H:i:s')." {$message}".PHP_EOL);
}

/**
 * Check total file size and delete files.
 * @param string $path Folder path containing log files
 * @param string $prefix Log filename prefix
 * @param int $limit Size limit in bytes
 */
function processFolder($path, $prefix, $limit) {
	$path = rtrim($path, '/').'/';

	$totalSize = 0;
	// This sorting **assumes** filename contain timestamp
	foreach (array_reverse(glob("{$path}{$prefix}*")) as $filename) {
		$totalSize += filesize($filename);

		if ($totalSize > $limit) {
			logInfo("Deleting {$filename}");
			unlink($filename);
		}
	}
}

/**
 * Entry point.
 */
function main() {
	global $logs;

	foreach ($logs as $folder) {
		echo "Processing {$folder['path']}\n";
		processFolder($folder['path'], $folder['prefix'], $folder['limit']);
	}
}

// Get started
main();