Provide example code to auto update certificates.

This is an example of how you could automatically update your
letsencrypt certificates.  This script examines all your existing
certificates and will only request them to be resigned if they are
within a month of expiring, or, they don't exist at all.

Licence: AGPLv3 with additional grants (see code)

Signed-Off-By: Rob Thomas <rthomas@sangoma.com>
Signed-Off-By: Rob Thomas <xrobau@gmail.com>

Author: xrobau

_auto_example.php

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+<?php
+// Lescript automatic updating script.
+//
+// This is an example of how Lescript can be used to automatically update
+// expiring certificates.
+//
+// This code is based on FreePBX's LetsEncrypt integration
+//
+// Copyright (c) 2016 Rob Thomas <rthomas@sangoma.com>
+// Licence:  AGPLv3.
+//
+// In addition, Stanislav Humplik <sh@analogic.cz> is explicitly granted permission
+// to relicence this code under the open source licence of their choice.
+
+if(!defined("PHP_VERSION_ID") || PHP_VERSION_ID < 50300 || !extension_loaded('openssl') || !extension_loaded('curl')) {
+    die("You need at least PHP 5.3.0 with OpenSSL and curl extension\n");
+}
+
+// Configuration:
+$domains = array('test.example.com', 'example.com');
+$webroot = "/var/www/html";
+$certlocation = "/usr/local/lescript";
+
+require 'Lescript.php';
+
+// Always use UTC
+date_default_timezone_set("UTC");
+
+// you can use any logger according to Psr\Log\LoggerInterface
+class Logger { function __call($name, $arguments) { echo date('Y-m-d H:i:s')." [$name] ${arguments[0]}\n"; }}
+$logger = new Logger();
+
+// Make sure our cert location exists
+if (!is_dir($certlocation)) {
+	// Make sure nothing is already there.
+	if (file_exists($certlocation)) {
+		unlink($certlocation);
+	}
+	mkdir ($certlocation);
+}
+
+// Do we need to create or upgrade our cert? Assume no to start with.
+$needsgen = false;
+
+// Do we HAVE a certificate for all our domains?
+foreach ($domains as $d) {
+	$certfile = "$certlocation/$d/cert.pem";
+
+	if (!file_exists($certfile)) {
+		// We don't have a cert, so we need to request one.
+		$needsgen = true;
+	} else {
+		// We DO have a certificate.
+		$certdata = openssl_x509_parse(file_get_contents($certfile));
+
+		// If it expires in less than a month, we want to renew it.
+		$renewafter = $certdata['validTo_time_t']-(86400*30);
+		if (time() > $renewafter) {
+			// Less than a month left, we need to renew.
+			$needsgen = true;
+		}
+	}
+}
+
+// Do we need to generate a certificate?
+if ($needsgen) {
+	try {
+		$le = new Analogic\ACME\Lescript($certlocation, $webroot, $logger);
+		# or without logger:
+		# $le = new Analogic\ACME\Lescript($certlocation, $webroot);
+		$le->initAccount();
+		$le->signDomains($domains);
+
+	} catch (\Exception $e) {
+		$logger->error($e->getMessage());
+		$logger->error($e->getTraceAsString());
+		// Exit with an error code, something went wrong.
+		exit(1);
+	}
+}
+
+// Create a complete .pem file for use with haproxy or apache 2.4,
+// and save it as domain.name.pem for easy reference. It doesn't
+// matter that this is updated each time, as it'll be exactly
+// the same. 
+foreach ($domains as $d) {
+	$pem = file_get_contents("$certlocation/$d/fullchain.pem")."\n".file_get_contents("$certlocation/$d/private.pem");
+	file_put_contents("$certlocation/$d.pem", $pem);
+}
+
+