PHP & Web Development Blogs

Search Results For: metrics
Showing 1 to 3 of 3 blog articles.
5936 views · 3 years ago

At Nomad PHP our goal is to empower developers in building a habit of continuous learning - and that means we have a habit of continuous improvement ourselves. Here are just some of the things we've done this year (with much more coming down the road)!

Website Redesign

We've refreshed the look and feel of Nomad PHP to better emphasize the goal of Nomad PHP - to help developers build a habit of continuous learning and grow their careers. This includes numerous usability enhancements as well as a focus on our new book library, blogs, and certification in addition to virtual meetups, workshops, conferences, and on-demand videos.

Free Meetups

As technology has advanced, more and more meetups and usergroups are able to stream their local usergroup meetings.

As our goal has always been to make technology accessible, we are proud to provide free streaming technology for local user groups, and share local user group meetings on our live virtual meetup schedule.

Student and Professional subscribers will continue to have access to our monthly conference level Pro Talks, hands on virtual workshops, and live conference streams in addition to streams by local user groups.

You can find a list of all upcoming talks (free and Pro) on our Live Meetings Page, or add your user group stream here.

Free Subscriber Tier

As our mission has evolved from being the meetup for developers without a meetup group to building an inclusive community of PHP developers where you can network, grow your skills, and share your knowledge with others - we are excited to announce our new Free Tier.

With a free Nomad PHP account you can:

* Stream free meetups

* Watch ad-supported videos in SD

* Read PHP blogs and write your own

* Network with other PHP developers

Create your free developer account to get started.

New Student Tier

To provide the best value, we've also restructured our plans to provide professional online meetings, workshops, and conference streaming to our Student Tier. This will allow students and new developers the chance to learn from the best speakers and top practioners and obtain entry level certifications at the best price possible.

However, with the addition of PHP Books and Magazines, and in order to provide the best value while keeping the Student plan affordable, new Student subscribers will not have access to the PHP Book and Magazine Library, or advanced certifications. These will now require a professional plan.

Student plans start at $12.95/mo

PHP Books and Magazines

We're excited to announce that we have expanded our PHP library. In addition to the ability to read the latest issues of php[architect] magazine, Professional subscribers now have access to read PHP and web development books online.

We're excited to announce the availability of Chris Hartjes' bookThe Grumpy Programmer's Guide to Testing PHP Applications, as well as several titles from Notes for Professionals, andUndisturbed REST: a Guide to Designing the Perfect API.

More titles including exclusive titles will be made available for online reading soon.

You can view our entire PHP Library here.

Blog Updates

We've received a lot of feedback on the blog writing process, and have upgraded several aspects of our blogging software. This includes the ability to save drafts prior to publishing, and the ability to upload, edit, and crop images and videos. We've also added some bug fixes for editing and writing code.

We're also excited to share that members with Student and Professional plans can now have their ownVLOG (video blog) with the ability to screencast/ record video from your webcam within the blog.

To see the most recent blog posts, or write your own, visit the Nomad PHP Blogs.

Certification Updates

We've updated our certifications for better usability and readability. We've also reworked some of the code samples and questions in our Level 1 PHP Certification exam.

You can find our available exams, test your skills, and obtain your Nomad PHP certification here.

Team Management

Our new team manager allows you to easily add or remove team members with your Nomad PHP team subscription. You'll also find real time metrics on how your team is using Nomad PHP, who on your team is investing in their growth and streaming meetups, watching videos, reading books, and earning certifications, and the overall content value consumed by your team.

The Team Manager is available to new teams, and will be made available to existing team managers over the next several weeks.

2020 Roadmap

There's still plenty of more great things coming in 2020. Here are the items at the top of our list:

* Mobile app for offline viewing

* Desktop app for offline viewing

* Nomad PHP member only books

* PHP Level 2 Certification

* Interactive tutorials

* Better video support in blogs

* Ability to schedule blog posts

* Meeting software for local usergroups

* Improved plan management for subscribers
Of course, what's most important to us is what's most important to you. Leave what you want to see on Nomad PHP in the comments below and if we're able to we'll get it added to our roadmap!
15325 views · 5 years ago
Create Alarm and Monitoring on Custom Memory and Disk Metrics for Amazon EC2

Today I am going write a blog on how to Monitor Memory and Disk custom metrics and creating alarm in Ubuntu.

To do this, we can use Amazon CloudWatch, which provides a flexible, scalable and reliable solution for monitoring our server.

Amazon Cloud Watch will allow us to collect the custom metrics from our applications that we will monitor to troubleshoot any issues, spot trends, and configure operational performance. CloudWatch functions display alarms, graphs, custom metrics data and including statistics.

Installing the Scripts

Before we start installing the scripts for monitoring, we should install all the dependent packages need to perform on Ubuntu.

First login to your AWS server, and from our terminal, install below packages

sudo apt-get update
sudo apt-get install unzip
sudo apt-get install libwww-perl libdatetime-perl

Now Install the Monitoring Scripts

Following are the steps to download and then unzip we need to configure the Cloud Watch Monitoring scripts on our server:
1. In the terminal, we need to change our directory and where we want to add our monitoring scripts.
2. Now run the below command and download the source:

curl -O

3. Now uncompress the currently downloaded sources using the following commands

unzip && \

rm && \

cd aws-scripts-mon

The directory will contain Perl scripts, because of the execution of these scripts only report memory run and disk space utilization metrics will run in our Ubuntu server.
Currently, our folder will contain the following files: - This Perl file is used to displaying the current utilization statistics reports for our AWS instance on which these file scripts will be executed. - This Perl script file will be used for collecting the system metrics on our ubuntu server and which will send them to the Amazon Cloud Watch.
awscreds.template - This Perl script file will contain an example for AWS credentials keys and secret access key named with access key ID. - This Perl script file module will be used to simplify by calling Amazon Cloud Watch from using other scripts.
LICENSE.txt – This file contains the license details for Apache 2.0.
NOTICE.txt – This file contains will gives us information about Copyright notice.
4. For performing the Cloud Watch operations, we need to confirm that whether our scripts have corresponding permissions for the actions:

If we are associated with an IAM role with our EC2 Ubuntu instance, we need to verify that which will grant the permissions to perform the below-listed operations:





Now we need to copy the ‘awscreds.template’ file into ‘awscreds.conf’ by using the command below and which will update the file with details of the AWS credentials.

cp awscreds.template awscreds.conf

AWSAccessKeyId = my_access_key_id

AWSSecretKey = my_secret_access_key

Now we completed the configuration.

This Perl script file will collect memory, disk space utilization data and swap the current system details and then it makes handling a remote call to Amazon Cloud Watch to reports details to the collected cloud watch data as a custom metrics.

We can perform a simple test run, by running the below without sending data to Amazon CloudWatch

./ --mem-util --verify --verbose

Now we are going to set a cron for scheduling our metrics and we will send them to Amazon CloudWatch
1. Now we need to edit the crontab by using below command:

 crontab -e

2. Now we will update the file using the following query which will disk space utilization and report memory for particular paths to Amazon CloudWatch in every five minutes:

*/5 * * * * ~/STORAGE/cloudwatch/aws-scripts-mon/ --mem-util --mem-avail --mem-used --disk-space-util --disk-space-avail --disk-space-used --disk-path=/ --disk-path=/STORAGE --from-cron

If there is an error, the scripts will write an error message in our system log.

Use of Options

The above command will collect the information about used memory and which will send the details of the reports in MBs into the MemoryUsed metrics. This will give us information about the metric counts memory allocated by applications and the OS as used.
The above command will collect the information about memory utilization in percentages and which will send the details of the Memory Utilization metrics and it will count the usage of the memory applications and the OS.
The above command will collect the information to collect the current utilized disk space and which will send the reports in percentages to the DiskSpaceUtilization for the metric and for the selected disks.
The above command will collect the information about the available memory and which will send the reports in MBs to the MemoryAvailable metrics details. This is the metric counts memory allocated by the applications and the OS as used.
The above command will collect the information and will point out the which disk path to report disk space.
The above command will collect the information about the available disk space and which will send the reports in GBs to the DiskSpaceAvailable metric for the selected disks.
The above command will collect the information about the disk space used and which will send the reports in GBs to the DiskSpaceUsed metric for the selected disks.

The PATH can specify to point or any of the files can be located on which are mounted point for the filesystem which needs to be reported.

If we want to points to the multiple disks, then specify both of the disks like below:

--disk-path=/ --disk-path=/home

Setting an Alarm for Custom Metrics

Before we are going to running our Perl Scripts, then we need to create an alarm that will be listed in our default metrics except for the custom metrics. You can see some default metrics are listed in below image:

Once we completed setting the cron, then the custom metrics will be located in Linux System Metrics.

Now we are going to creating the alarm for our custom metrics
1. We need to open the cloudwatch console panel at
2. Now navigate to the navigation panel, we need to click on Alarm and we can Create Alarm.
3. This will open a popup which with the list of the CloudWatch metrics by category.
4. Now click on the Linux System Metrics . This will be listed out with custom metrics you can see in the below pictures

5. Now we need to select metric details and we need to click on the NEXT button. Now we need to navigate to Define Alarm step.

6. Now we need to define an Alarm with required fields

Now we need to enter the Alarm name for identifying them. Then we need to give a description of our alarm.

Next, we need to give the condition with the maximum limit of bytes count or percentage when it notifies the alarm. If the condition satisfies, then the alarm will start trigger.

We need to provide a piece of additional information about for our alarm.

We need to define what are the actions to be taken when our alarm changes it state.

We need to select or create a new topic with emails needed for sending notification about alarm state.
7. Finally, we need to choose the Create Alarm.

So its completed. Now the alarm is created for our selected custom metrics.


Now the alarm will be listed out under the selected state in our AWS panel. Now we need to select an alarm from the list seen and we can see the details and history of our alarm.
12568 views · 5 years ago
Creating a PHP Daemon Service

What is a Daemon?

The term daemon was coined by the programmers of Project MAC at MIT. It is inspired on Maxwell's demon in charge of sorting molecules in the background. The UNIX systems adopted this terminology for daemon programs.

It also refers to a character from Greek mythology that performs the tasks for which the gods do not want to take. As stated in the "Reference System Administrator UNIX", in ancient Greece, the concept of "personal daemon" was, in part, comparable to the modern concept of "guardian angel." BSD family of operating systems use the image as a demon's logo.

Daemons are usually started at machine boot time. In the technical sense, a demon is considered a process that does not have a controlling terminal, and accordingly there is no user interface. Most often, the ancestor process of the deamon is init - process root on UNIX, although many daemons run from special rcd scripts started from a terminal console.

Richard Stevenson describes the following steps for writing daemons:
    . Resetting the file mode creation mask to 0 function umask(), to mask some bits of access rights from the starting process.
    . Cause fork() and finish the parent process. This is done so that if the process was launched as a group, the shell believes that the group finished at the same time, the child inherits the process group ID of the parent and gets its own process ID. This ensures that it will not become process group leader.
    . Create a new session by calling setsid(). The process becomes a leader of the new session, the leader of a new group of processes and loses the control of the terminal.
    . Make the root directory of the current working directory as the current directory will be mounted.
    . Close all file descriptors.
    . Make redirect descriptors 0,1 and 2 (STDIN, STDOUT and STDERR) to /dev/null or files /var/log/project_name.out because some standard library functions use these descriptors.
    . Record the pid (process ID number) in the pid-file: /var/run/
    . Correctly process the signals and SigTerm SigHup: end with the destruction of all child processes and pid - files and / or re-configuration.

How to Create Daemons in PHP

To create demons in PHP you need to use the extensions pcntl and posix. To implement the fast communication withing daemon scripts it is recommended to use the extension libevent for asynchronous I/O.

Lets take a closer look at the code to start a daemon:
$pid = pcntl_fork(); 
if ($pid < 0) {
print('fork failed');
exit 1;

After a fork, the execution of the program works as if there are two branches of the code, one for the parent process and the second for the child process. What distinguishes these two processes is the result value returned the fork() function call. The parent process ID receives the newly created process number and the child process receives a 0.
if ($pid > 0) { echo "daemon process started
exit; }

$sid = posix_setsid(); if ($sid < 0) {
exit 2;

chdir('/'); file_put_contents($pidFilename, getmypid() );

The implementation of step 5 "to close all file descriptors" can be done in two ways. Well, closing all file descriptors is difficult to implement in PHP. You just need to open any file descriptors before fork(). Second, you can override the standard output to an error log file using init_set() or use buffering using ob_start() to a variable and store it in log file:
$content = ob_get_clean();
fwrite($fd_log, $content); 

Typically, ob_start() is the start of the daemon life cycle and ob_get_clean() and fwrite() calls are the end. However, you can directly override STDIN, STDOUT and STDERR:
ini_set('error_log', $logDir.'/error.log');
$STDIN = fopen('/dev/null', 'r');
$STDOUT = fopen($logDir.'/application.log', 'ab');
$STDERR = fopen($logDir.'/application.error.log', 'ab');

Now, our process is disconnected from the terminal and the standard output is redirected to a log file.

Handling Signals

Signal processing is carried out with the handlers that you can use either via the library pcntl (pcntl_signal_dispatch()), or by using libevent. In the first case, you must define a signal handler:
function sig_handler($signo)
global $fd_log;
switch ($signo) {
fclose($fd_log); unlink($pidfile); exit;
case SIGHUP:
init_data(); break;

pcntl_signal(SIGTERM, "sig_handler");
pcntl_signal(SIGHUP, "sig_handler");

Note that signals are only processed when the process is in an active mode. Signals received when the process is waiting for input or in sleep mode will not be processed. Use the wait function pcntl_signal_dispatch(). We can ignore the signal using flag SIG_IGN: pcntl_signal(SIGHUP, SIG_IGN); Or, if necessary, restore the signal handler using the flag SIG_DFL, which was previously installed by default: pcntl_signal(SIGHUP, SIG_DFL);

Asynchronous I/O with Libevent

In the case you use blocking input / output signal processing is not applied. It is recommended to use the library libevent which provides non-blocking as input / output, processing signals, and timers. Libevent library provides a simple mechanism to start the callback functions for events on file descriptor: Write, Read, Timeout, Signal.

Initially, you have to declare one or more events with an handler (callback function) and attach them to the basic context of the events:
$base = event_base_new();
$event = event_new();
$errno = 0;
$errstr = '';
$socket = stream_socket_server("tcp://$IP:$port", $errno, $errstr);
stream_set_blocking($socket, 0); event_set($event, $socket, EV_READ | EV_PERSIST, 'onAccept', $base);

Function handlers 'onRead', 'onWrite', 'onError' must implement the processing logic. Data is written into the buffer, which is obtained in the non-blocking mode:
function onRead($buffer, $id)
while($read = event_buffer_read($buffer, 256)) {

The main event loop runs with the function event_base_loop($base);. With a few lines of code, you can exit the handler only by calling: event_base_loobreak(); or after the specified time (timeout) event_loop_exit();.

Error handling deals with failure Events:
function onError($buffer, $error, $id)
global $id, $buffers, $ctx_connections;
event_buffer_disable($buffers[$id], EV_READ | EV_WRITE);
unset($buffers[$id], $ctx_connections[$id]);

It should be noted the following subtlety: Working with timers is only possible through the file descriptor. The example of official the documentation does not work. Here is an example of processing that runs at regular intervals.
$event2 = event_new();
$tmpfile = tmpfile();
event_set($event2, $tmpfile, 0, 'onTimer', $interval);
$res = event_base_set($event2, $base);
event_add($event2, 1000000 * $interval);

With this code we can have a working timer finishes only once. If we need a "permanent" Timer, using the function onTimer we need create a new event each time, and reassign it to process through a "period of time":
function onTimer($tmpfile, $flag, $interval)
$global $base, $event2;

if ($event2) {


$event2 = event_new();
event_set($event2, $tmpfile, 0, 'onTimer', $interval);
$res = event_base_set($event2, $base);
event_add($event2, 1000000 * $interval);

At the end of the daemon we must release all previously allocated resources:

event_base_set($event, $base);

Also it should be noted that for the signal processing handler is set the flag EV_SIGNAL: event_set($event, SIGHUP, EV_SIGNAL, 'onSignal', $base);

If needed constant signal processing, it is necessary to set a flag EV_PERSIST. Here follows a handler for the event onAccept, which occurs when a new connection is a accepted on a file descriptor:
function onAccept($socket, $flag, $base) {
global $id, $buffers, $ctx_connections;
$connection = stream_socket_accept($socket);
stream_set_blocking($connection, 0);
$buffer = event_buffer_new($connection, 'onRead', NULL, 'onError', $id);
event_buffer_base_set($buffer, $base);
event_buffer_timeout_set($buffer, 30, 30);
event_buffer_watermark_set($buffer, EV_READ, 0, 0xffffff); event_buffer_priority_set($buffer, 10); event_buffer_enable($buffer, EV_READ | EV_PERSIST); $ctx_connections[$id] = $connection;
$buffers[$id] = $buffer;

Monitoring a Daemon

It is good practice to develop the application so that it was possible to monitor the daemon process. Key indicators for monitoring are the number of items processed / requests in the time interval, the speed of processing with queries, the average time to process a single request or downtime.

With the help of these metrics can be understood workload of our demon, and if it does not cope with the load it gets, you can run another process in parallel, or for running multiple child processes.

To determine these variables need to check these features at regular intervals, such as once per second. For example downtime is calculated as the difference between the measurement interval and total time daemon.

Typically downtime is determined as a percentage of a measurement interval. For example, if in one second were executed 10 cycles with a total processing time of 50ms, the time will be 950ms or 95%.

Query performance wile be 10rps (request per second). Average processing time of one request: the ratio of the total time spent on processing requests to the number of requests processed, will be 5ms.

These characteristics, as well as additional features such as memory stack size queue, number of transactions, the average time to access the database, and so on.

An external monitor can be obtain data through a TCP connection or unix socket, usually in the format of Nagios or zabbix, depending on the monitoring system. To do this, the demon should use an additional system port.

As mentioned above, if one worker process can not handle the load, usually we run in parallel multiple processes. Starting a parallel process should be done by the parent master process that uses fork() to launch a series of child processes.

Why not run processes using exec() or system()? Because, as a rule, you must have direct control over the master and child processes. In this case, we can handle it via interaction signals. If you use the exec command or system, then launch the initial interpreter, and it has already started processes that are not direct descendants of the parent process.

Also, there is a misconception that you can make a demon process through command nohup. Yes, it is possible to issue a command: nohup php mydaemon.php -master >> /var/log/daemon.log 2 >> /var/log/daemon.error.log &

But, in this case, would be difficult to perform log rotation, as nohup "captures" file descriptors for STDOUT / STDERR and release them only at the end of the command, which may overload of the process or the entire server. Overload demon process may affect the integrity of data processing and possibly cause partial loss of some data.

Starting a Daemon

Starting the daemon must happen either automatically at boot time, or with the help of a "boot script."

All startup scripts are usually in the directory /etc/rc.d. The startup script in the directory service is made /etc/init.d/ . Run command start service myapp or start group /etc/init.d/myapp depending on the type of OS.

Here is a sample script text:
#! /bin/sh
$appdir = /usr/share/myapp/app.php
$parms = --master –proc=8 --daemon
export $appdir
export $parms
if [ ! -x appdir ]; then
exit 1

if [ -x /etc/rc.d/init.d/functions ]; then
. /etc/rc.d/init.d/functions


start () {
echo "Starting app"
daemon /usr/bin/php $appdir $parms
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/mydaemon
return $RETVAL

stop () {
echo -n "Stopping $prog: "
killproc /usr/bin/fetchmail
[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/mydaemon
return $RETVAL

case in
status /usr/bin/mydaemon
echo "Usage:
if (is_file('app.phar')) {
$phar = new Phar('app.phar', 0, 'app.phar');
$phar->setSignatureAlgorithm (Phar::SHA1);
$files = array();
$files['bootstrap.php'] = './bootstrap.php';
$rd = new RecursiveIteratorIterator(new RecursiveDirectoryIterator('.'));
foreach($rd as $file){
if ($file->getFilename() != '..' && $file->getFilename() != '.' && $file->getFilename() != __FILE__) {
if ( $file->getPath() != './log'&& $file->getPath() != './script'&& $file->getPath() != '.')
$files[substr($file->getPath().DIRECTORY_SEPARATOR.$file->getFilename(),2)] =
if (isset($opt['version'])) {
$version = $opt['version'];
$file = "buildFromIterator(new ArrayIterator($files));
$phar = null;

exit $RETVAL

Distributing Your PHP Daemon

To distribute a daemon it is better to pack it in a single phar archive module. The assembled module should include all the necessary PHP and .ini files.

Below is a sample build script:
#php app.phar
myDaemon version 0.1 Debug
--daemon – run as daemon
--debug – run in debug mode
--settings – print settings
--nofork – not run child processes
--check – check dependency modules
--master – run as master
--proc=[8] – run child processes

Additionally, it may be advisable to make a PEAR package as a standard unix-console utility that when run with no arguments prints its own usage instruction:


Creating daemons in PHP it is not hard but to make them run correctly it is important to follow the steps described in this article.

Post a comment here if you have questions or comments on how to create daemon services in PHP.