Version 5 supported

Using Silverstripe CMS with Composer


Composer is a package management tool for PHP that lets you install and upgrade Silverstripe CMS and its modules. We also have separate instructions for installing modules with Composer.

Before installing Composer you should ensure your system has the version control system Git installed. Composer uses Git to check out the code dependencies you need to run your Silverstripe CMS website from the code repositories maintained on GitHub.

Next, install Composer. For our documentation we assume the composer command is installed globally. You should now be able to run the command:

composer help

If you already have Composer installed, make sure it is composer 2 by running composer --version. If you're running Composer 1, run composer self-update. You may also want to check out the upgrade guide for Composer 1.x to 2.0.

Create a new site

Composer can create a new site for you, using the installer as a template. By default it will download the latest stable version:

composer create-project silverstripe/installer my-project

With the above command, my-project is the path (relative to your current working directory) where Composer will create the project.

For example, on OSX, you might want to create a project as a sub-directory of ~/Sites. You could do that by running cd ~/Sites before the above command.

If that directory doesn't exist, Composer will create it for you.

If you want to get additional fixtures for testing, such as behat and phpunit configuration, an example .env.example file, and all documentation, then it's recommended to use the --prefer-source option to include these files.

If you want a minimal installation with the bare essentials to get working without any additional overhead, and don't plan on contributing back changes to framework, use the --prefer-dist option (which is implied by default) for a more lightweight install.

This will get all the code that you need. As long as your web server and database are up and running, you can now visit the site in your web browser and the installation process will be completed.

You can also specify a constraint to download explicit versions or set boundary conditions for what versions Composer is allowed to install. For example, this will download the latest patch of the 4.13 release:

composer create-project silverstripe/installer ./my-project ^4.13

Learn more about Composer constraints in the official composer documentation

When create-project is used with a release version like above, it will try to get the code from archives instead of creating git repositories. If you're planning to contribute to Silverstripe CMS, see Using development versions.

Adding modules to your project

Composer isn't only used to download Silverstripe CMS, it is also used to manage all Silverstripe CMS modules and any other PHP dependencies you may have. You can find thousands of Silverstripe CMS modules on Packagist. Installing a module can be done with the require command:

composer require silverstripe/blog

This will install the silverstripe/blog module in the latest compatible version. If you know the specific version you want to install already (such as ^2), you can add it after the package name as a version constraint:

composer require silverstripe/blog ^2

Version constraints: master or main is not a legal version string - it's a branch name. These are different things. The version string that would get you the branch is dev-main. The version string that would get you a numeric branch is a little different. The version string for the 5 branch is 5.x-dev.

Updating dependencies

Except for the control code of the Voyager space probe, every piece of code in the universe gets updated from time to time. Silverstripe CMS modules are no exception.

To get the latest updates of the modules in your project, run the update command:

composer update

Updates to the required modules will be installed, and the composer.lock file will get updated with the specific commits and version constraints for each of them.

The update command can also be used to downgrade dependencies - if you edit your composer.json file and set a version constraint that will require a lower version to be installed, running composer update will "update" your installed dependencies to match your constraints, which in this case would install lower versions than what you had previously.

You may occasionally need to use the --with-all-dependencies option when downgrading dependencies to avoid conflicting version constraints.

Deploying projects with Composer

When deploying projects with Composer, you could just push the code and run composer update. This, however, is risky. In particular, if you were referencing development dependencies and a change was made between your testing and your deployment to production, you would end up deploying untested code. Not cool!

The composer.lock file helps with this. It references the specific commits that have been checked out, rather than the version string. You can run composer install to install dependencies from this rather than composer.json.

So your deployment process, as it relates to Composer, should be as follows:

  • Run composer update on your development version before you start whatever testing you have planned. Perform all the necessary testing.
  • Check composer.lock into your repository.
  • Deploy your project code base, using the deployment tool of your choice.
  • Run composer install --no-dev -o on your production version. In this command, the --no-dev command tells Composer not to install your development-only dependencies, and -o is an alias for --optimise-autoloader, which will convert your PSR-0 and PSR-4 autoloader definitions into a classmap to improve the speed of the autoloader.

Composer managed modules, Git and .gitignore

Modules and themes managed by Composer should not be committed with your project's source code. Silverstripe CMS recipes ship with a .gitignore file by default which prevents this. For more details read Should I commit the dependencies in my vendor directory? .

Dev environments for contributing code

So you want to contribute to Silverstripe CMS? Fantastic! You can do this with Composer too. You have to tell Composer three things in order to be able to do this:

  • Keep the full git repository information
  • Include dependencies marked as "developer" requirements
  • Use the development version, not the latest stable version

The first two steps are done as part of the initial create project using additional arguments.

composer create-project --keep-vcs silverstripe/installer ./my-project 5.x-dev --prefer-source

The process will take a bit longer, since all modules are checked out as full git repositories which you can work on. The command checks out from the 5.x release line. If you are providing a patch to fix a bug, replace 5.x-dev with the latest minor branch instead, e.g. 5.1.x-dev if the latest minor release was for CMS 5.1.

The --keep-vcs flag will make sure you have access to the git history of the installer and the requirements.

It's also a good idea to require silverstripe/recipe-testing as a dev dependency - it adds a few modules which are useful for Silverstripe CMS development:

  • The behat-extension module allows running Behat integration tests
  • The phpunit library is used to run unit and functional tests
  • The php_codesniffer library is used to lint PHP to ensure it adheres to our coding conventions.

Please read the Contributing Code documentation to find out how to create forks and send pull requests.

Advanced usage

Manually editing composer.json

To remove dependencies, or if you prefer seeing your dependencies in a text file, you can edit the composer.json file. It will appear in your project root, and by default, it will look something like this:

    "name": "silverstripe/installer",
    "type": "silverstripe-recipe",
    "description": "The SilverStripe Framework Installer",
    "require": {
        "php": "^8.1",
        "silverstripe/recipe-plugin": "^2",
        "silverstripe/vendor-plugin": "^2",
        "silverstripe/recipe-cms": "~5.0.0@stable",
        "silverstripe-themes/simple": "~3.2.0",
        "silverstripe/login-forms": "~5.0.0@stable"
    "require-dev": {
        "phpunit/phpunit": "^9.5"
    "extra": {
        "project-files-installed": [
        "public-files-installed": [
    "config": {
        "process-timeout": 600,
        "allow-plugins": {
            "composer/installers": true,
            "silverstripe/recipe-plugin": true,
            "silverstripe/vendor-plugin": true
    "prefer-stable": true,
    "minimum-stability": "dev"

To add modules, you should add more entries into the "require" section. For example, we might add the blog and forum modules.

Be careful with the commas at the end of the lines! You can run composer validate to be sure your composer.json file is formatted correctly.

Save your file, and then run the following command to update the installed packages:

composer update

Using development versions

Composer will by default download the latest stable version of silverstripe/installer. The composer.json file that comes with silverstripe/installer may also explicitly state it requires the stable version of CMS and framework - this is to ensure that when developers are getting started, running composer update won't upgrade their project to an unstable version

However it is relatively easy to tell Composer to use development versions. Not only is this required if you want to contribute back to the Silverstripe CMS project, it also allows you to get fixes and API changes early.

This is a two step process. First you get Composer to start a project based on the latest unstable silverstripe/installer

composer create-project silverstripe/installer ./my-project 5.x-dev

Or for the latest development version in the 5.0.x minor release (i.e. if you're developing a bug fix)

composer create-project silverstripe/installer ./my-project 5.0.x-dev

Working with project forks and unreleased modules

By default, Composer will install modules listed on the Packagist site. There are a few reasons that you might not want to do this. For example:

  • You may have your own fork of a module, either specific to a project, or because you are working on a pull request
  • You may have a module that hasn't been released to the public.

There are many ways that you can address this, but this is one that we recommend, because it minimises the changes you would need to make to switch to an official version in the future.

This is how you do it:

  • Ensure that all of your fork repositories have correct composer.json files. Set up the project forks as you would a distributed package. If you have cloned a repository that already has a composer.json file, then there's nothing you need to do, but if not, you will need to create one yourself.
  • List all your fork repositories in your project's composer.json files. You do this in a repositories section. Set the type to vcs, and url to the URL of the repository. The result will look something like this:
    "name": "silverstripe/installer",
    "description": "The Silverstripe Framework Installer",
    "repositories": [
            "type": "vcs",
            "url": ""
  • Install the module as you would normally. Use the regular Composer commands - there are no special flags to use a fork. Your fork will be used in place of the package version, so long as it meets the dependency version constraint.
composer require silverstripe/cms

In most cases, you will probably have a specific branch of the fork you want to install. You should use the appropriate version constraint to install that branch. For example, to install a branch called fix/issue-1990 your version constraint should be dev-fix/issue-1990.

Depending on what other installed modules have that package as a dependency, you may also need to declare an inline alias.

See more about this in Forks and branch names below.

Composer will scan all of the repositories you list, collect meta-data about the packages within them, and use them in favour of the packages listed on packagist. To switch back to using the mainline version of the package, just remove the repositories section from composer.json and run composer update.

Now add an "upstream" remote to the original repository location so you can rebase or merge your fork as required.

cd cms
git remote add -f upstream git://

For more information, read the "Repositories" chapter of the Composer documentation.

Forks and branch names

For simplicity, you should keep using the same pattern of branch names as the main repositories does. If your version is a fork of 5.0, then call the branch 5.0, not 5.0-myproj or myproj. Otherwise, the dependency resolution gets confused.

Sometimes, however, this isn't feasible. For example, you might have a number of project forks stored in a single repository, such as your personal GitHub fork of a project. Or you might be testing/developing a feature branch. Or it might just be confusing to other team members to call the branch of your modified version 5.0.

In this case, you need to use Composer's aliasing feature to specify how you want the project branch to be treated, when it comes to dependency resolution.

Open composer.json, and find the module's require. Then put as (core version name) on the end.

    "require": {
        "php": "^8.1",
        "silverstripe/recipe-cms": "~5.0.0@stable",
        "silverstripe/framework": "dev-myproj as 5.0.0",
        "silverstripe-themes/simple": "~3.2.0"

What this means is that when the myproj branch is checked out into a project, this will satisfy any dependencies that 5.0.0 would meet. So, if another module has "silverstripe/framework": "^5.0.0" in its dependency list, it won't get a conflict.

Both the version and the alias are specified as Composer versions, not branch names. For the relationship between branch/tag names and Composer versions, read the relevant Composer documentation.

This is not the only way to set things up in Composer. For more information on this topic, read the "Aliases" chapter of the Composer documentation.


How should I name my module?

Follow the advice on choosing a unique name and vendor prefix. Please don't use the silverstripe/<modulename> vendor prefix, since that's reserved for modules produced by Silverstripe Ltd. In order to declare that your module is in fact a Silverstripe CMS module, use the silverstripe tag in the composer.json file, and set the "type" to silverstripe-vendormodule.

What about themes?

Themes are technically just "modules" which are placed in the themes/ subdirectory. We denote a special type for them in the composer.json ("type": "silverstripe-theme"), which triggers their installation into the correct path.

Themes should not have any PHP code in them - if your theme needs some PHP code to function correctly, add that PHP code to a separate module and include it as a dependency in the theme's composer.json file.

Do I need Composer on my live server?

It depends on your deployment process. If you copy or rsync files to your live server, you won't need Composer on the live server. If the live server hosts a git repository checkout, which is updated to push a newer version, you'll need to run composer install checking out the code. We recommend looking into Composer "lock" files for this purpose.

Can I keep using downloads, subversion externals or Git submodules?

Composer is more than just a file downloader. It comes with additional features such as autoloading and scripts which some modules rely on. You really should be using Composer to manage your PHP dependencies.

I don't want to get development versions of everything

You don't have to, Composer is designed to work on the constraints you set. You can declare the "minimum-stability" on your project as suitable, or even whitelist specific modules as tracking a development branch while keeping others to their stable release. Read up on Composer "lock" files on how this all fits together.