Project Structure and Autoloading in Bitrix

Baseline: main 23.0+. Features newer than baseline are marked Since.

Three Root Sections

• /bitrix/ — system files. Never edit them directly: any hotfix will be lost during an update.
• /local/ — all user code. If a file doesn't exist — create it manually. With the same path, a file in /local/ takes precedence over /bitrix/.
• /upload/ — files uploaded by users and modules.

What to Put in /local/

/local/
├── modules/<vendor>.<module>/   # Custom modules (PSR-4 autoloading)
├── components/<vendor>/<name>/  # Components (class.php, templates/.default/)
├── templates/<id>/              # Site templates + /components/, /page_templates/
├── routes/
│   └── web.php                  # Routing entry (Since main 21.400)
├── activities/                  # Business process actions
├── gadgets/                     # Desktop gadgets
├── blocks/                      # Sites24 blocks
├── js/                          # Custom JS extensions
├── php_interface/
│   ├── init.php                 # Loaded on every hit
│   ├── after_connect_d7.php     # After DB connect (charset, sql_mode, TZ)
│   ├── dbconn.php               # Since main 24.100 — can live here
│   └── user_lang/               # User interface translations
├── .settings.php                # Kernel configuration (Since main 24.100)
└── .settings_extra.php          # Overrides (Since main 24.100)

Set the same permissions for /local/php_interface/ as for /bitrix/php_interface/ — it may contain sensitive files.

Including a Module (Loader)

Prefer Bitrix\Main\Loader in new code. Treat CModule::IncludeModule* as legacy compatibility.

Situation	API
Module is mandatory; failure must abort	Loader::requireModule('vendor.module')
Optional integration with a real false branch	Loader::includeModule(...) and handle false
Shareware/demo status codes	Loader::includeSharewareModule() / legacy CModule::IncludeModuleEx() — not plain includeModule

use Bitrix\Main\Loader;

// Mandatory — fail-fast (preferred when no fallback exists)
Loader::requireModule('vendor.module');

// Optional — must handle false explicitly
if (Loader::includeModule('vendor.analytics'))
{
    // enrich behaviour
}

includeModule / requireModule:

• Includes include.php and /lib/autoload.php of the module.
• Registers the module namespace for PSR-4 autoloading.
• Registers module services into ServiceLocator.

Rules:

• Do not call includeModule without handling false when the dependency is actually required — use requireModule.
• Load a required module once near the scenario boundary; do not repeat the same check deep in call stacks.
• Do not flip global behaviour with Loader::setRequireThrowException(false) to fake a bool API — call includeModule instead.
• Do not introduce new CModule::IncludeModule() in greenfield code.

PSR-4 Autoloading of Classes in /lib/

The rule is simple: folder name = namespace part, file name = class name (both in PascalCase).

/local/modules/vendor.module/lib/
├── Application/Service/PostService.php        # \Vendor\Module\Application\Service\PostService
├── Infrastructure/Controller/Post.php         # \Vendor\Module\Infrastructure\Controller\Post
├── Model/PostTable.php                         # \Vendor\Module\Model\PostTable
└── Cli/Command/Feature/RebuildCommand.php      # \Vendor\Module\Cli\Command\Feature\RebuildCommand

Namespace from module id:

• Partner module vendor.module → \Vendor\Module
• One-word module mymodule → \Bitrix\Mymodule (kernel rule in Loader)

If the PSR-4 structure is followed — nothing needs to be registered manually.

Manual Registration (When Needed)

In rare cases (mixed folders, non-PSR-4 legacy), you can specify in /local/modules/vendor.module/include.php:

\Bitrix\Main\Loader::registerNamespace(
    'Vendor\\Module\\Legacy',
    $_SERVER['DOCUMENT_ROOT'] . '/local/modules/vendor.module/legacy',
);

\Bitrix\Main\Loader::registerAutoLoadClasses('vendor.module', [
    'Vendor\\Module\\OldClass' => 'classes/old_class.php',
]);

Prefer registerNamespace for a folder with PSR-4 structure. registerAutoLoadClasses is a last resort.

Composer

Composer dependencies are placed in /local/vendor/ (/local/composer.json). Keep composer.json outside DOCUMENT_ROOT when possible.

In .settings.php:

'composer' => [
    'value' => ['config_path' => '../composer.json'], // path relative to DOCUMENT_ROOT
    'readonly' => true,
],

Required for bitrix/bitrix.php (make:* commands, Since main 25.900). Do not install packages in /bitrix/vendor/ — they disappear on kernel update.

Additional Files

• /bitrix/routing_index.php — entry point for new routing (configure web server to forward here).
• /local/php_interface/after_connect_d7.php — included after successful DB connection (ConnectionPool → include_after_connected). Typical uses: SET NAMES, sql_mode, DB timezone.
• /local/php_interface/virtual_file_system.php — virtual filesystem overrides.

JS Extensions

Custom frontend code lives in /local/js/<module>/<extension>/. Load via Extension::load('module.extension'). See skill bitrix-extensions.

Configuration Files

• /bitrix/.settings.php or /local/.settings.php — primary D7 kernel config.
• /bitrix/.settings_extra.php or /local/.settings_extra.php — overrides without API.
• /bitrix/php_interface/dbconn.php or /local/php_interface/dbconn.php — constants for old kernel and compatibility.

Global vs module .settings.php

Section	Where	Notes
connections, cache, session, routing, crypto, exception_handling, loggers, messenger	Global only	Read by kernel config
controllers, services, console	Module (and optionally global for services)	Module services register on includeModule
routing in module .settings.php	Not used by router	See below

Module routes (not auto-loaded)

The router loads only files listed in global routing.config from /local/routes/ and /bitrix/routes/.

Canonical pattern — keep module route file and require it from /local/routes/web.php:

// /local/routes/web.php
return function (\Bitrix\Main\Routing\RoutingConfigurator $routes): void {
    $file = $_SERVER['DOCUMENT_ROOT'] . '/local/modules/vendor.module/routes/web.php';
    if (is_file($file)) {
        (require $file)($routes);
    }
};

See skill bitrix-routing.

File Priority

• Components: /local/components/<vendor>/<name>/ override /bitrix/components/<vendor>/<name>/.
• Component templates in a site template: /local/templates/<id>/components/... override everything else.
• System files (e.g., header.php) are searched first in /local/, then in /bitrix/.
• Modules: /local/modules/<id>/ takes precedence over /bitrix/modules/<id>/ when both exist.

When php_interface/init.php is Needed

Only for:

• Registering dynamic event handlers that cannot be tied to the installation of a specific module.
• Project constants that must be available before modules are included.
• Compatibility hooks.

For everything else — create a module and use its install/index.php, include.php, and .settings.php.