PHP Config File: Keep Settings in One Place

Settings such as the site name, database host or items per page should live in one place. Then you change them once, not in twenty files.

A config file that returns an array

config.php

PHP

<?php
return [
    "app" => [
        "name" => "Code Corner",
        "debug" => false,
    ],
    "db" => [
        "host" => "127.0.0.1",
        "name" => "shop",
    ],
    "per_page" => 10,
];

index.php

PHP

<?php
$config = require __DIR__ . "/config.php";

echo $config["app"]["name"] . "\n";
echo $config["db"]["host"] . "\n";
echo $config["per_page"];

Output

OUTPUT

1
2
3

Code Corner
127.0.0.1
10

A small helper for nested keys

Typing $config["db"]["host"] everywhere is long. A helper accepts a dotted path.

index.php

PHP

<?php
function config(string $path, mixed $default = null): mixed
{
    static $config = [
        "app" => ["name" => "Code Corner"],
        "db" => ["host" => "127.0.0.1"],
    ];

    $value = $config;

    foreach (explode(".", $path) as $key) {
        if (!is_array($value) || !array_key_exists($key, $value)) {
            return $default;
        }
        $value = $value[$key];
    }

    return $value;
}

echo config("db.host") . "\n";
echo config("db.port", 3306);

Output

OUTPUT

1
2

127.0.0.1
3306

Keep secrets out of the repository

Settings like the database password and API keys must not be committed to Git. Two common ways:

Read them from environment variables (see Environment Variables).
Keep a private config file outside the repository, and list it in .gitignore.

config.php

PHP

<?php
return [
    "db" => [
        "host" => getenv("DB_HOST") ?: "127.0.0.1",
        "user" => getenv("DB_USER") ?: "root",
        "pass" => getenv("DB_PASS") ?: "",
    ],
];

Do not keep config in the public folder

If config.php is inside the web folder and PHP stops working for any reason, a visitor could download your settings as plain text. Put configuration above the public folder, so the server never serves it.

Constants or arrays?

	Array in a file	`define()` / `const`
Nested values	Easy	Awkward
Change per environment	Easy	Possible
Available everywhere	After loading	Yes

Most modern projects use arrays (or environment variables) and pass them to the code that needs them.

lightbulb

Group by purpose

Put database, mail and app settings in separate keys. A reader finds what they need in seconds, and a typo in one group does not affect another.