1) Drush can now use Composer to manage dependencies and extensions for both Drupal 8 and Drupal 7 sites. Composer is used to manage Drush and Drupal core together. 2) Drush implements a "site-local" approach to avoid dependency hell issues between extensions and core. Each Drupal site can have its own isolated version of Drush that will be used. 3) Drush extensions that use Composer libraries need to be included in the Drupal project's composer.json file. The drush_autoload function ensures extensions work with both Composer-managed and non-Composer sites.

1. Drush in the Composer Era
1Photo © 2012 by Charlie Nguyen, CC BY 2.0

2. 2
Overview
Using Composer Dependency Hell Site-Local Drush
Configuration Filter The FutureDrush Extensions

3. It is now possible to use Composer to
add code directly to Drupal:
drush dl drupal-8
cd drupal-8
composer require drupal/og:8.*
composer update will not update
drupal/core; use drush pm-update
drupal for this.
3
Standard Composer used in D8

4. web
├── autoload.php
├── composer.json
├── core
│ └─ composer.json
├── index.php
└── vendor
└─ autoload.php
4
wikimedia/composer-merge-plugin
{
"name": "drupal/drupal",
"require": {
"composer/installers": "^1.0.21",
"wikimedia/composer-merge-plugin": "^1.3.0"
},
"extra": {
"_readme": [
"By default Drupal loads the autoloader from ./vendor/autoload.php.",
"To change the autoloader you can edit ./autoload.php."
],
"merge-plugin": {
"include": [
"core/composer.json"
],
"recurse": false,
"replace": false,
"merge-extra": false
}
},
}

5. Uses “split core” to manage Drupal
core files:
composer create-project drupal-
composer/drupal-project:8.x-dev
my-site-name --stability dev --
no-interaction
5
Drupal 8: “drupal-project”

6. project
├── composer.json
├── vendor
│ └── autoload.php
└── web
├── autoload.php
├── core
│ └── composer.json
└── index.php
6
drupal-project Layout
{
"name": "drupal-composer/drupal-project",
"repositories": [
{
"type": "composer",
"url": "https://packagist.drupal-composer.org"
}
],
"require": {
"composer/installers": "^1.0.20",
"drupal/core": "8.0.*",
"drush/drush": "dev-master",
"drupal/console": "dev-master"
},
"extra": {
"installer-paths": {
"web/core": ["type:drupal-core"],
"web/modules/contrib/{$name}": ["type:drupal-module"],
"drush/contrib/{$name}": ["type:drupal-drush"]
}
}
}

7. 7
Drupal 7: Example CI Scripts
example-drupal7-circle-composer
example-drupal7-travis-composer
CI
+
+

8. Use craychee/rootcanal to post-
process your Composer install:
"config": {
"bin-dir": "bin"
},
"scripts": {
"post-install-cmd": [
"bin/rootcanal"
],
"post-update-cmd": [
"bin/rootcanal"
]
}
}
http://craychee.io/blog/2015/08/01/no-excuses-part3-composer/ 8
Drupal 7: rootcanal

9. Dependency Hell
9

10. The Multiple Autoloaders Problem
10
Two autoloaders may directly or indirectly include the same dependent library.
Drupal 8
require autoload.php
Badly-Behaved Drush Extension
require autoload.php
"name": "symfony/event-dispatcher",
"version": "v2.7.5",
"name": "symfony/event-dispatcher",
"version": "3.*",

11. Version Mismatch Breaks
11
Event
isPropagationStopped
stopPropagation
symfony/event-dispatcher v2.7.5 symfony/event-dispatcher v3.x
public function dispatch($event_name, Event $event) {
$event->setDispatcher($this);
Event
isPropagationStopped
stopPropagation
setDispatcher
getDispatcher
getName
setName
DrupalComponentEventDispatcherContainerAwareEventDispatcher.dispatch

12. Site-Local Drush
12
Solution to Dependency Hell
Well-Behaved Drush Extensions

13. Site-Local Drush
13

14. Drush dispatch now happens in four phases:
14
Drush Dispatch
Drush Finder Drush Wrapper Drush Launcher
Drush
Application

15. 15
Drush Finder
Responsible for finding the correct Drush to run
● Checks to see if it can find a Drupal site
● If the Drupal site contains a Drush script, use it
● If no Site-Local Drush is found, use global Drush
Does not look at alias files.
PHP Script

16. Optional. Located at the Drupal Root if it exists.
User may customize this script to:
● Add site-specific options (e.g. commandfile
locations)
● Select the location of the Drush launcher (if in a
non-standard location)
If there is no Drush Wrapper, then the Drush Finder
will find and execute the Drush Launcher.
16
Drush Wrapper
Shell Script

17. 17
Drush Launcher
Sets up the PHP operating environment.
● Select php.ini file to use
● Select php executable to use
● Passes info about environment to Drush
Always launches the Drush that is located next to it.
Shell Script

18. 18
Drush Application
Contains all the code that is Drush.
● Load configuration and command file
● Parse site alias files
● Might dispatch again, e.g. if site alias is remote
PHP
Application

19. Manage Drush and Drupal
Place Drush and Drupal in the same composer.json file:
cd /path/to/drupal-8-root
composer require drush/drush:8.*
It is also possible to use site-local Drush with a non-Composer-managed
Drupal site just to attach a specific version of Drush to that site:
cd /path/to/old/drupal-root
composer require drush/drush:6.*
19
CRITICAL

20. Drush Extensions
20Photo © 2011 by Shawn Clover, CC BY-NA 2.0

21. PROBLEM:
A Drush extension desires to use Composer
Libraries, but also wants to work with both
Composer-managed sites, and sites that do
not use Composer.
SOLUTION:
Include a composer.json file as usual, and
require libraries there. In your drush extension’
s hook_drush_init, call drush_autoload
(__FILE__).
21
Composer Libraries in Extensions
my.drush.inc:
function my_drush_init() {
drush_autoload(__FILE__);
}

22. IT’S SIMPLE.
If Drush has located a Drupal site that has an autoloader, then it assumes that
all extensions that need an autoloader are part of the Drupal site’s composer.
json file. Drush only loads Drupal’s autoload.php.
If the Drupal site does not have an autoloader, then Drush will find the
extension’s autoloader, and load it.
AN EXTENSION CAN’T GET THIS RIGHT. ALWAYS USE
drush_autoload.
22
drush_autoload Function

23. Global Extensions
23
Drush Extensions that use Composer libraries must be included locally as part
of your Drupal project:
cd /path/to/project
composer require drupal/drush_iq
Policy files can continue to live in a global location, e.g. $HOME/.drush.

24. 24
Include Global Extensions in Project
{
"name": "drupal/drupal",
"require": {
"composer/installers": "^1.0.21",
"wikimedia/composer-merge-plugin": "^1.3.0",
"drush/drush": "dev-master"
},
"extra": {
"merge-plugin": {
"include": [
"/Users/ME/.drush-extensions/composer.json"
],
"recurse": false,
"replace": false,
"merge-extra": false
}
},
}
Drupal Project
composer.json:
Global Extensions List
composer.json:
$HOME
└── .drush-extensions
├── composer.json
├── composer.lock
├── drush
│ └── registry_rebuild
│ ├── registry_rebuild.drush.inc
│ └── registry_rebuild.php
└── vendor
└── autoload.php

25. Drush Configuration Filter
25

26. Configuration Workflow
26
Code and Content move in only one direction, but Configuration can move in
either direction.

27. To keep development modules out of exported configuration, define:
__ROOT__/drush/drushrc.php:
$command_specific['config-export']['skip-modules'] = array('devel');
$command_specific['config-import']['skip-modules'] = array(‘devel');
This only works with the Drush config-import and config-export
commands. Use caution with the Configuration Synchronization admin page.
27
Configuration Filter

28. The Future
28

29. Drush and Drupal Console
29
The more code you have, the more code you
have to maintain.
However, the maintenance process adds value.
New code should benefit from existing code.
Duplicate functions that do the same thing should
be avoided to reduce maintenance requirements.
&

30. Drush Bootstrap Refactor
30
Drush now has separate bootstrap
classes for each framework
Boot
validRoot($path);
DrupalBoot6
validRoot($path);
DrupalBoot7
validRoot($path);
DrupalBoot8
validRoot($path);
SOMEDAY?

31. By factoring Site Aliases and Backend Invoke into separate libraries, the “Drush
Finder” can handle remote dispatches.
31
Refactor into Composer Libraries
Drush Finder Drush Wrapper Drush Launcher Drush Application

32. cd /path/to/drupal-project
composer require pantheon-systems/behat-drush-endpoint
32
Drush Driver Enhancement
YES!