Lecture Notes On Class 33:
PHP Configuration and Environment
Objective:
- Learn
to configure PHP settings and manage the PHP environment.
- Understand
how to use environment variables for configuration.
Outcome:
- Students
will be able to modify PHP configuration settings and manage environment
variables effectively.
1.
Introduction to PHP Configuration
PHP configuration is essential
for controlling the behavior of PHP scripts on the server. The primary
configuration file for PHP is called php.ini, where we can adjust various
settings related to:
- File
upload limits
- Memory
usage
- Error
reporting
- Time
zones
- Session
handling
These settings enable us to
optimize the PHP environment based on the project’s requirements.
2. The php.ini File
The php.ini file
contains directives (settings) that control various aspects of PHP's behavior.
Each directive has a default value, which can be modified to suit specific
application needs.
- Location
of php.ini:
- It
can vary depending on the operating system and PHP installation.
- To
locate it, you can use the phpinfo() function in a PHP script:
php
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<?php
phpinfo();
?>
- The
location of the php.ini file is displayed under
“Loaded Configuration File.”
- Commonly
Modified Directives:
- memory_limit:
Sets the maximum amount of memory a script can use.
- upload_max_filesize
and post_max_size: Define limits on file upload sizes.
- max_execution_time:
Sets the maximum time (in seconds) a script is allowed to run.
- display_errors
and error_reporting: Control error display and level of error
reporting.
Example:
To change the maximum file upload
size, locate and modify these lines in php.ini:
ini
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upload_max_filesize = 10M
post_max_size = 10M
After making changes, restart the
web server for the settings to take effect.
3. Using .htaccess for PHP
Configuration
On Apache servers, PHP settings
can also be modified using an .htaccess file. This is helpful if you
don’t have access to php.ini or want to set different configurations for specific directories.
- Example
of .htaccess Configuration:
apache
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php_value memory_limit 256M
php_value upload_max_filesize 10M
php_flag display_errors On
- php_value is
used to set values, and php_flag is used to enable or
disable flags.
4.
Setting Environment Variables
Environment variables allow
configuration values to be stored outside of the code, making applications more
secure and flexible. These variables are commonly used for:
- Database
credentials
- API
keys
- Other
sensitive or environment-specific information
Using
Environment Variables in PHP
1. Create an
Environment File:
o
Environment variables are often stored in a .env file in
the root of the project. This file is not included in the version control
(e.g., Git) to keep sensitive information secure.
2. Add
Environment Variables to .env:
plaintext
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DB_HOST=localhost
DB_USER=root
DB_PASS=secret
3. Access
Environment Variables in PHP:
o
You can load environment variables using libraries
like vlucas/phpdotenv in
Composer:
bash
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composer require vlucas/phpdotenv
o
Then, initialize it in your script:
php
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<?php
require 'vendor/autoload.php';
$dotenv = Dotenv\Dotenv::createImmutable(__DIR__);
$dotenv->load();
echo getenv('DB_HOST'); //
Output: localhost
?>
5. PHP
Configuration Functions
PHP offers several built-in
functions for accessing and modifying configuration settings dynamically:
- ini_get():
Retrieves the current value of a configuration option.
php
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echo ini_get('memory_limit'); //
Output: 128M (or the current value)
- ini_set():
Sets the value of a configuration option temporarily within the script.
php
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ini_set('memory_limit', '256M');
- getenv() and
putenv(): Access and modify environment variables in
PHP.
php
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echo getenv('DB_HOST'); //
Output: localhost
putenv('APP_MODE=production');
6. Error
Reporting Configuration
Configuring error reporting is
essential for debugging during development. PHP’s display_errors
directive determines if errors are shown in the browser.
- Development
Settings:
php
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ini_set('display_errors', '1'); //
Show errors
error_reporting(E_ALL); // Report
all types of errors
- Production
Settings:
php
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ini_set('display_errors', '0'); //
Hide errors
error_reporting(0); // Suppress
error reporting
Use different configurations in php.ini or .env files
for development and production environments to avoid exposing sensitive
information to end users.
7.
Practical Example: Configuring PHP for a File Upload Application
Suppose we’re creating an
application that allows users to upload files. Here’s a sample configuration:
1. Open php.ini and set
appropriate values:
ini
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upload_max_filesize = 5M
post_max_size = 6M
max_execution_time = 60
2. Use
Environment Variables for Database Credentials:
o
In the .env file:
plaintext
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DB_HOST=localhost
DB_NAME=mydatabase
DB_USER=root
DB_PASS=secret
3. Access
the Environment Variables in PHP:
php
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$db_host = getenv('DB_HOST');
$db_user = getenv('DB_USER');
$db_pass = getenv('DB_PASS');
4. Handle
Errors Gracefully:
php
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ini_set('display_errors', '1');
error_reporting(E_ALL);
Summary
- PHP
Configuration is managed through php.ini, .htaccess,
and functions like ini_set().
- Environment
Variables are useful for securely storing configuration
values outside of the codebase.
- Error
Reporting settings vary by environment (development vs.
production) and should be configured appropriately.
- Use
libraries like vlucas/phpdotenv to load and access
environment variables securely in PHP.
By understanding these concepts,
students will be able to configure PHP environments effectively, making
applications more secure, efficient, and tailored to specific requirements.