Getting Started with PHP: PHP and Prometheus

PHP, as an open source scripting language, has a history of more than 20 years. It is mainly used for web development, especially for server-side scripts. PHP is very widely used and it is used to build many large-scale web applications and websites.

Prometheus is an open source monitoring system and time series database. Its main purpose is to collect and store system and application metrics data and provide query and visualization tools. Because Prometheus is highly scalable and flexible, it has become one of the most popular monitoring tools in the open source community.

This article will provide readers with a PHP introductory guide, introducing the basic knowledge and practical cases of PHP and Prometheus.

1. Basic knowledge of PHP

If you are a newbie, you need to know the basics of PHP, especially the use of syntax and variables. The following are some basic concepts:

1.1 PHP syntax

PHP uses tags to identify code blocks: . These tags can appear anywhere and therefore can be embedded in other text files (such as HTML). Generally speaking, PHP files should end with the .php file extension.

In PHP, variables start with the $ symbol. PHP variables can store numbers, text, or other data types.

1.2 PHP variable types and scope

Variable types in PHP include Boolean values, integers, floating point numbers, strings, arrays, objects and null values ​​(null). The main scopes of PHP variables are as follows:

• Local variables: declared inside the function;
• Global variables: declared outside the function (or using the global keyword);
• Static variables: declared inside a function but remain unchanged between function calls.

1.3 PHP control structure

There are a variety of control structures (such as if, for and while loops) in PHP. These structures can be used to implement the control flow of conditional statements and loop statements. . Here is an example:

<?php
$x = 10;
if ($x > 5) {
    echo "x is greater than 5";
} else {
    echo "x is less than or equal to 5";
}
?>

In this example, if the value of variable $x is greater than 5, then the code block will print "x is greater than 5".

2. Basic knowledge of Prometheus

Prometheus is a monitoring system and time series database, mainly used to collect and store indicator data of systems and applications. It consists of server side and client side. The following are some basic concepts:

2.1 Prometheus indicators

Prometheus uses indicators to represent the data that needs to be monitored. The indicator consists of the following attributes:

• Name: the indicator name, consisting of letters, numbers and underscores;
• Label: the text identification of the indicator, used to distinguish the indicator from other Indicators are distinguished;
• Value (value): the pure numeric value of the indicator.

The following is an example indicator:

http_requests_total{method="GET",handler="/api/v1/users"}

In this example, the indicator name is http_requests_total, the labels are method and handler, and the value is the total number of requests.

2.2 Prometheus collector

Prometheus uses a collector to obtain indicator data. The collector can be an application or a middleware component. Prometheus predefines some standard collector interfaces, such as Node Exporter and Blackbox Exporter.

2.3 PromQL

Prometheus Query Language (PromQL) is used to query and aggregate metric data. It allows users to create complex queries and returns results in an easy-to-understand format. For example:

http_requests_total{method="GET",handler="/api/v1/users"}[5m]

This example queries the total number of GET /api/v1/users requests in the last 5 minutes.

3. PHP and Prometheus integration

The integration of Prometheus and PHP allows developers to monitor and optimize the performance and health of their web applications. Using Prometheus, you can monitor response time, number of requests, etc. The following are some integration methods and examples:

3.1 Prometheus client library

The PHP developer community has provided some libraries to help use Prometheus. The most popular of these is the php-prometheus-client library. Developers can use this library to add Prometheus metrics to PHP applications. For example:

require 'vendor/autoload.php';
use PrometheusCollectorRegistry;
use PrometheusCounter;
$registry = new CollectorRegistry();
$requests = new Counter('http_requests_total', 'The total number of HTTP requests.', ['method', 'handler'], $registry);
$requestCount = $requests->inc(['GET', '/api/v1/users']);

This example uses the Counter class in the php-prometheus-client library, which can be used to count the number of HTTP requests.

3.2 Prometheus Push Gateway

Another tool for integrating PHP applications into Prometheus is Push Gateway. Push Gateway allows PHP applications to push metric data to a centralized Prometheus instance. This tool is also a standalone application that can query data using the PromQL query language.

The above is some introductory knowledge of PHP and Prometheus. Once you are familiar with these basic concepts, you will be able to use Prometheus to monitor the performance metrics of your PHP applications and optimize them.

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