Description of Magento 2 Directory Structure

What are the naming conventions, and how are namespaces established?

The root Magento directory contains these primary folders:

  • app/code: where your custom modules are found. Hopefully, very few 3rd- party modules are installed here because it is difficult to remember to keep these up-to-date. Installing modules through Composer provides the module vendor with an easier way to automatically update their modules and dependencies.

  • app/design/[frontend or adminhtml]: this is where themes are stored.

  • app/i18n: this is where translation (language) packages are stored.

  • app/etc/: this is where the configuration files are stored:
    • app/etc/env.php: this is the configuration file that is per environment. This contains your database, redis, and queueing (Advanced Message Queuing Protocol or AMQP) configuration, among other things. This file should NOT be in your Git repository as it contains sensitive information.
    • app/etc/config.php: this file should be committed to your Git repository. It ultimately merges with the env.php file. This holds the configuration for enabling/disabling modules and can include defaults for Store Configuration and theming.

  • bin/: you will type the command bin/magento thousands of times in your tenure as Magento developer … so this is where this file is stored.

  • dev/: this contains the configuration for built-in tools, such as Grunt. It also contains Magento’s test suite.

  • generated/: files in this folder are created by Magento. While it is technically safe to delete in production, it’s a bad idea as it will result in downtime or a slowdown on the website while Magento rebuilds this directory. This is where Magento stores factory classes, interceptor classes (used to make plugins work), proxy classes (used to lazy-load methods to prevent the constructor from triggering too early and causing a problem elsewhere in the system), and extension attribute interfaces and classes.

  • lib/: this folder contains the internal libraries on which Magento relies. Note that jQuery is found in lib/web/jquery/.

  • pub/: this is the directory that should be HTTP root (i.e., the directory that is browsed when you go to https://bkaushik.com) for the webserver. While the root Magento folder would work, you risk exposing folders such as your var folder with a misconfiguration. When you browse to a Magento website, the webserver first checks to see if that exact path exists as a file. If it doesn’t, the .htaccess or Nginx configuration rewrites the request to pub/index.php, which begins the normal Magento request.
    • pub/media/: this is where the website’s images are stored.
    • pub/static/: this contains the .css, .js and .html files that have been processed and are ready for the end-user to download. If a path is requested but doesn’t exist as a file in this folder, Magento tries to create it when not in production mode (or if you add a store with a new language). If your website is in developer mode, and you run bin/magento dev:source- theme:deploy, most files in this directory will be symlinked to their sources throughout the Magento codebase. In production mode, you run bin/magento setup:static-content:deploy to process and copy files to this directory.
      What’s the difference? dev:source-theme:deploy creates symlinks from module’s LESS files into the pub/static directory. This allows LESS files changes, in modules, to always be of the latest version. setup:static-content:deploy copies all necessary files (JS, HTML and LESS compiled to CSS) to the pub/static directory. Once this command is run, changes to your LESS and JS files in your module will not be visible on the frontend.

  • setup/: this directory contains important files related to installing Magento. If your webserver is configured so that the document root matches the Magento root directory (ie, not /pub), you can browse to your website /setup URL. This configuration should be very temporary, and production’s document root should always be /pub. Why? Because a simple misconfiguration (face it, this can happen) can expose sensitive information in the var/ or other directories. Magento provides an easy way to avoid this issue by ensuring a correct document root.

    But what if I need to install Magento? Either use the /setup URL (by changing your application’s document root) temporarily. Or, better yet, use the CLI command: bin/magento setup:install.

  • var/: this directory contains files that are temporarily used by the Magento application or results from using it. For example, logs are in var/log/. Error reports are in var/report. If you are using the file-system cache, this is stored in var/cache and var/page_cache. You should only use file- system caches in your development environment and never on production. The reason is that file-system storage prevents horizontal scaling (scaling Magento to multiple stand-alone instances)

  • vendor/: this is where all of the Composer-installed modules are located.
    This directory can be deleted and re-created at any time on your development machine (doing this in production would result in your store being down). To create this directory, run composer install (this command is different than composer update in that install doesn’t change any versions and only installs what is specified in composer.lock).

    Because of this, it goes without saying that code in the vendor/ directory should never be modified. Doing so will be temporary and these changes will be destroyed next time you run composer update or composer install.

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