MediaWiki Developers

Welcome to the MediaWiki community! Please see How to become a MediaWiki hacker for general information on contributing to MediaWiki.

Development environment

MediaWiki provides an extendable local development environment based on Docker Compose. This environment provides PHP, Apache, Xdebug and a SQLite database.

Do not use the development environment to serve a public website! Bad things would happen!

More documentation, examples, and configuration recipes are available at mediawiki.org/wiki/Special:MyLanguage/MediaWiki-Docker.

Support is available on the Libera IRC network in the #mediawiki channel, and on Phabricator by creating tasks with the MediaWiki-Docker tag.

Quickstart

1. Requirements

You'll need to have Docker installed:

Docker Desktop for macOS or Windows.
Docker engine for Linux.

The container images provided by Wikimedia use an AMD64 Debian runtime and are not currently available in ARM64 or any 32-bit processor variants. ARM64 MacOS computers have been reported to work with these images via Rosetta AMD64 emulation.

Linux users:

We recommend installing docker-ce, docker-ce-cli, containerd.io, and docker-compose-plugin by downloading the server releases for your distribution rather than Docker Desktop. You can also install the binaries.
Follow the instructions to "Manage Docker as a non-root user"

Windows users:

Running Docker from a Windows terminal and using the Windows file system will result in MediaWiki being very slow. For Windows 10 and higher, we recommend configuring Docker and Windows to use the Windows Subsystem for Linux (WSL). Turn on WSL in your Windows settings, then run the following commands: wsl --install -d ubuntu and wsl --set-version ubuntu 2. Then go into Docker -> Settings -> General -> tick "Use the WSL 2 based engine", then go into Docker -> Settings -> Resources -> WSL Integration -> tick "Ubuntu". git clone the mediawiki repository into a WSL folder such as home/yourusername/mediawiki so that the files are inside WSL. Then you can run most of the commands in this tutorial outside of WSL, by opening PowerShell, navigating to the WSL directory with cd \\wsl.localhost\Ubuntu\home\yourusername\mediawiki, and executing shell commands as normal. To access WSL from PowerShell (rare but may be needed sometimes), you can use the command ubuntu to turn a PowerShell console into a WSL console. To navigate to WSL folders in File Explorer, show the Navigation Pane, then towards the bottom, look for "Linux" (it will be close to "This PC").

2. Download MediaWiki files

Download the latest MediaWiki files to your computer. One way to download the latest alpha version of MediaWiki is to install git, open a shell, navigate to the directory where you want to save the files, then type git clone https://gerrit.wikimedia.org/r/mediawiki/core.git mediawiki.

Optional: If you plan to submit patches to this repository, you will probably want to create a Gerrit account, then type git remote set-url origin ssh://YOUR-GERRIT-USERNAME-HERE@gerrit.wikimedia.org:29418/mediawiki/core, replacing YOUR-GERRIT-USERNAME-HERE with your Gerrit username. Please see the official MediaWiki Gerrit tutorial for more information.

3. Prepare `.env` file

Using a text editor, create a .env file in the root of the MediaWiki core repository, and copy these contents into that file:

MW_SCRIPT_PATH=/w
MW_SERVER=http://localhost:8080
MW_DOCKER_PORT=8080
MEDIAWIKI_USER=Admin
MEDIAWIKI_PASSWORD=dockerpass
XDEBUG_CONFIG=
XDEBUG_ENABLE=true
XHPROF_ENABLE=true

Windows users: Run the following command to add a blank user ID and group ID to your .env file:

echo "
MW_DOCKER_UID=
MW_DOCKER_GID=" >> .env

Non-Windows users: Run the following command to add your user ID and group ID to your .env file:

echo "MW_DOCKER_UID=$(id -u)
MW_DOCKER_GID=$(id -g)" >> .env

Linux users: If you'd like to use Xdebug features inside your IDE, then create a docker-compose.override.yml file as well:

services:
  mediawiki:
    # For Linux: This extra_hosts section enables Xdebug-IDE communication:
    extra_hosts:
      - "host.docker.internal:host-gateway"

4. Create the environment

Start the containers:
```
docker compose up -d
```
The "up" command makes sure that the PHP and webserver containers are running (and any others in the docker-compose.yml file). It is safe to run at any time, and will do nothing if the containers are already running.

The first time, it may take a few minutes to download new Docker images.

The -d argument stands for "detached" mode, which run the services in the background. If you suspect a problem with one of the services, you can run it without -d to follow the server logs directly from your terminal. You don't have to stop the services first, if you ran it with -d and then without, you'll get connected to the already running containers including a decent back scroll of server logs.

Note that MediaWiki debug logs go to /cache/*.log files (not sent to docker).

Install PHP dependencies from Composer:

docker compose exec mediawiki composer update

Install MediaWiki:
```
docker compose exec mediawiki /bin/bash /docker/install.sh
```
Windows users: make sure you run the above command in PowerShell as it does not work in Bash.
Windows users: Make sure to set the SQLite directory to be writable.
```
docker compose exec mediawiki chmod -R o+rwx cache/sqlite
```

Done! The wiki should now be available for you at http://localhost:8080.

Usage

Running commands

You can use docker compose exec mediawiki bash to open a Bash shell in the MediaWiki container. You can then run one or more commands as needed and stay within the container shell.

You can also run a single command in the container directly from your host shell, for example: docker compose exec mediawiki php maintenance/run.php update.

PHPUnit

Run a single PHPUnit file or directory:

docker compose exec mediawiki bash
instance:/w$ cd tests/phpunit
instance:/w/tests/phpunit$ composer phpunit -- path/to/my/test/

See PHPUnit on mediawiki.org for more examples.

Selenium

You can use Fresh to run Selenium in a dedicated container. Example usage:

fresh-node -env -net
npm ci
npm run selenium-test

API Testing

You can use Fresh to run API tests in a dedicated container. Example usage:

export MW_SERVER=http://localhost:8080/
export MW_SCRIPT_PATH=/w
export MEDIAWIKI_USER=Admin
export MEDIAWIKI_PASSWORD=dockerpass
fresh-node -env -net
# Create .api-testing.config.json as documented on
# https://www.mediawiki.org/wiki/Special:MyLanguage/MediaWiki_API_integration_tests
npm ci
npm run api-testing

Modify the development environment

You can override the default services from a docker-compose.override.yml file, and make use of those overrides by changing LocalSettings.php.

Example overrides and configurations can be found under MediaWiki-Docker on mediawiki.org.

After updating docker-compose.override.yml, run docker compose down followed by docker compose up -d for changes to take effect.

Install extra packages

If you need root on the container to install system packages with apt-get for troubleshooting, you can open a shell as root with docker compose exec --user root mediawiki bash.

Install extensions and skins

To install an extension or skin, follow the instructions of the mediawiki.org page for the extension or skin in question, and look for any dependencies or additional steps that may be needed.

For most extensions, only two steps are needed: download the code to the right directory, and then enable the component from LocalSettings.php.

To install the Vector skin:

Clone the skin:

cd skins/
git clone https://gerrit.wikimedia.org/r/mediawiki/skins/Vector

Enable the skin, by adding the following to LocalSettings.php:
```
wfLoadSkin( 'Vector' );
```

To install the EventLogging extension:

Clone the extension repository:

cd extensions/
git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/EventLogging

Alternatively, if you have extension repositories elsewhere on disk, mount each one as an overlapping volume in docker-compose.override.yml. This is comparable to a symlink, but those are not well-supported in Docker.

services:
  mediawiki:
    volumes:
      - ~/Code/EventLogging:/var/www/html/w/extensions/EventLogging:cached
  mediawiki-jobrunner:
    volumes:
      - ~/Code/EventLogging:/var/www/html/w/extensions/EventLogging:cached

Note: If the extension serves static assets directly (e.g., images, fonts), you may also need to mount the volume to the mediawiki-web service:

services:
  mediawiki-web:
    volumes:
      - ~/Code/EventLogging:/var/www/html/w/extensions/EventLogging:cached

Enable the extension, by adding the following to LocalSettings.php:
```
wfLoadExtension( 'EventLogging' );
```

Xdebug

By default, you will need to set XDEBUG_TRIGGER=1 in the GET/POST, or as an environment variable, to turn on Xdebug for a request.

You can also install a browser extension for controlling whether Xdebug is active. See the official Xdebug Step Debugging, particularly the "Activating Step Debugging" section, for more details.

If you wish to run Xdebug on every request, you can set start_with_request=yes in XDEBUG_CONFIG in your .env file:

XDEBUG_CONFIG=start_with_request=yes

You can pass any of Xdebug's configuration values in this variable. For example:

XDEBUG_CONFIG=client_host=192.168.42.34 client_port=9000 log=/tmp/xdebug.log

This shouldn't be necessary for basic use cases, but see the Xdebug settings documentation for available settings.

Codex

You can use your local version of Codex instead of the one bundled with MediaWiki. This is useful when testing how changes in Codex affect Codex-based features in MediaWiki.

Clone the Codex repository and build Codex, if you haven't done this already:

cd ../
git clone https://gerrit.wikimedia.org/r/design/codex
cd codex
npm run build-all

If your clone of the Codex repository is outside of the MediaWiki directory (this is common), add the following to your docker-compose.override.yml. Replace ~/git/codex with the path to your Codex clone.
```
services:
 mediawiki:
   volumes:
     - ~/git/codex:/var/www/html/w/codex:cached
```
To apply the change to docker-compose.override.yml, you have to recreate the environment:
```
docker compose down
docker compose up -d
```
Enable Codex development mode by adding the following to the bottom of LocalSettings.php:
```
$wgCodexDevelopmentDir = MW_INSTALL_PATH . '/codex';
```
To disable Codex development mode and use the regular version of Codex, delete or comment out this line.
Every time you make a change to your local copy of Codex (or download a Gerrit change), you have to rerun Codex's build process for these changes to take effect. To do this, run npm run build-all in the Codex directory.

Note: if your local changes only affect .vue or .ts files, you can run npm run quick-build instead of the full build, which will be much faster. This won't rebuild TypeScript definitions or design token values, icons or i18n messages but can be handy for re-building small changes. If it is the first time you build Codex locally, running npm run build-all is still necessary.

Stop or recreate environment

Stop the environment, perhaps to reduce the load when working on something else. This preserves the containers, to be restarted later quickly with the docker compose up -d command.

docker compose stop

Destroy and re-create the environment. This will delete the containers, including any logs, caches, and other modifications you may have made via the shell.

docker compose down
docker compose up -d

Re-install the database

To empty the wiki database and re-install it:

Remove or rename the LocalSettings.php file.
Delete the cache/sqlite directory.
Re-run the "Install MediaWiki database" command.

You can now restore or copy over any modifications you had in your previous LocalSettings.php file. And if you have any additional extensions installed that required a database table, then also run: docker compose exec mediawiki php maintenance/run.php update.

Troubleshooting

Caching

If you suspect a change is not applying due to caching, start by hard refreshing the browser.

If that doesn't work, you can narrow it down by disabling various server-side caching layers in LocalSettings.php, as follows:

$wgMainCacheType = CACHE_NONE;
$wgMessageCacheType = CACHE_NONE;
$wgParserCacheType = CACHE_NONE;
$wgResourceLoaderMaxage = [
  'versioned' => 0,
  'unversioned' => 0
];

The default settings of MediaWiki are such that caching is smart and changes propagate immediately. Using the above settings may slow down your wiki significantly. Especially on macOS and Windows, where Docker Desktop uses a VM internally and thus has longer file access times.

See Manual:Caching on mediawiki.org for more information.

Xdebug ports

Older versions of Xdebug used port 9000, which could conflict with php-fpm running on the host. This document used to recommend a workaround of telling your IDE to listen on a different port (e.g., 9009) and setting XDEBUG_CONFIG=remote_port=9009 in your .env.

Xdebug 3.x now uses the client_port value, which defaults to 9003. This should no longer conflict with local php-fpm installations, but you may need to change the settings in your IDE or debugger.

Linux desktop, host not found

The image uses host.docker.internal as the client_host value which should allow Xdebug work for Docker for Mac/Windows.

On Linux, you need to create a docker-compose.override.yml file with the following contents:

services:
  mediawiki:
    extra_hosts:
      - "host.docker.internal:host-gateway"

With the latest version of Docker on Linux hosts, this should work transparently as long as you're using the recommended docker-compose.override.yml. If it doesn't, first check docker version to make sure you're running Docker 20.10.2 or above, and docker compose version to make sure it's 1.27.4 or above.

If Xdebug still doesn't work, try specifying the hostname or IP address of your host. The IP address works more reliably. You can obtain it by running e.g. ip -4 addr show docker0 and copying the IP address into the config in .env, like XDEBUG_CONFIG=remote_host=172.17.0.1

Generating logs

Switching on the remote log for Xdebug comes at a performance cost so only use it while troubleshooting. You can enable it like so: XDEBUG_CONFIG=remote_log=/tmp/xdebug.log

"(Permission Denied)" errors on running docker compose

See if you're able to run any docker commands to start with. Try running docker container ls, which should also throw a permission error. If not, go through the following steps to get access to the socket that the docker client uses to talk to the daemon.

sudo usermod -aG docker $USER

And then relogin (or newgrp docker) to re-login with the new group membership.

"(Cannot access the database: Unknown error (localhost))"

The environment's working directory has recently changed to /var/www/html/w. Reconfigure this in your LocalSettings.php by ensuring that the following values are set correctly:

$wgScriptPath = '/w';
$wgSQLiteDataDir = "/var/www/html/w/cache/sqlite";

Windows users, "(Cannot access the database: No database connection (unknown))"

The permissions with the cache/sqlite directory have to be set manually on Windows:

docker compose exec mediawiki chmod -R o+rwx cache/sqlite

Linux users, "(Cannot access the database: No database connection (localhost))"

Make sure you have the MW_DOCKER_UID and MW_DOCKER_GID set in your .env file (instructions above).

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MediaWiki Developers

Development environment

Quickstart

1. Requirements

2. Download MediaWiki files

3. Prepare `.env` file

4. Create the environment

Usage

Running commands

PHPUnit

Selenium

API Testing

Modify the development environment

Install extra packages

Install extensions and skins

Xdebug

Codex

Stop or recreate environment

Re-install the database

Troubleshooting

Caching

Xdebug ports

Linux desktop, host not found

Generating logs

"(Permission Denied)" errors on running docker compose

"(Cannot access the database: Unknown error (localhost))"

Windows users, "(Cannot access the database: No database connection (unknown))"

Linux users, "(Cannot access the database: No database connection (localhost))"

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MediaWiki Developers

Development environment

Quickstart

1. Requirements

2. Download MediaWiki files

3. Prepare .env file

4. Create the environment

Usage

Running commands

PHPUnit

Selenium

API Testing

Modify the development environment

Install extra packages

Install extensions and skins

Xdebug

Codex

Stop or recreate environment

Re-install the database

Troubleshooting

Caching

Xdebug ports

Linux desktop, host not found

Generating logs

"(Permission Denied)" errors on running docker compose

"(Cannot access the database: Unknown error (localhost))"

Windows users, "(Cannot access the database: No database connection (unknown))"

Linux users, "(Cannot access the database: No database connection (localhost))"

3. Prepare `.env` file