composer

Estimated reading time: 6 minutes

Composer is a dependency manager written in and for PHP.

GitHub repo: https://github.com/composer/docker

Library reference

This content is imported from the official Docker Library docs, and is provided by the original uploader. You can view the Docker Hub page for this image at https://hub.docker.com/images/composer

Supported tags and respective Dockerfile links

Quick reference

What is Composer?

Composer is a tool for dependency management in PHP, written in PHP. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you.

You can read more about Composer in our official documentation.

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How to use this image

Basic usage

Running the composer image is as simple as follows:

$ docker run --rm --interactive --tty \
  --volume $PWD:/app \
  composer install

Persistent cache / global configuration

You can bind mount the Composer home directory from your host to the container to enable a persistent cache or share global configuration:

$ docker run --rm --interactive --tty \
  --volume $PWD:/app \
  --volume $COMPOSER_HOME:/tmp \
  composer install

Note: this relies on the fact that the COMPOSER_HOME value is set to /tmp in the image by default.

Or if you are following the XDG specification:

$ COMPOSER_HOME=$HOME/.config/composer \
  COMPOSER_CACHE_DIR=$HOME/.cache/composer \
  docker run --rm --interactive --tty \
  --env COMPOSER_HOME \
  --env COMPOSER_CACHE_DIR \
  --volume $COMPOSER_HOME:$COMPOSER_HOME \
  --volume $COMPOSER_CACHE_DIR:$COMPOSER_CACHE_DIR \
  --volume $PWD:/app \
  composer install

Filesystem permissions

By default, Composer runs as root inside the container. This can lead to permission issues on your host filesystem. You can work around this by running the container with a different user:

$ docker run --rm --interactive --tty \
  --volume $PWD:/app \
  --user $(id -u):$(id -g) \
  composer install

Private repositories / SSH agent

When you need to access private repositories, you will either need to share your configured credentials, or mount your ssh-agent socket inside the running container:

$ docker run --rm --interactive --tty \
  --volume $PWD:/app \
  --volume $SSH_AUTH_SOCK:/ssh-auth.sock \
  --env SSH_AUTH_SOCK=/ssh-auth.sock \
  composer install

Note: This currently does not work on OSX, see docker/for-mac#410.

When combining the use of private repositories with running Composer as another user, you might run into non-existent user errors (thrown by ssh). To work around this, simply mount the host passwd and group files (read-only) into the container:

$ docker run --rm --interactive --tty \
  --volume $PWD:/app \
  --volume $SSH_AUTH_SOCK:/ssh-auth.sock \
  --volume /etc/passwd:/etc/passwd:ro \
  --volume /etc/group:/etc/group:ro \
  --env SSH_AUTH_SOCK=/ssh-auth.sock \
  --user $(id -u):$(id -g) \
  composer install

Troubleshooting

PHP versions

Our image is aimed at quickly running Composer without the need for having a PHP runtime installed. You should not rely on the PHP version in our container. We do not provide a Composer image for each supported PHP version because we do not want to encourage using Composer as a base image or a production image.

Suggestions:

  • use --ignore-platform-reqs:

    $ composer install --ignore-platform-reqs

  • specify the target platform in your composer.json:

    {
  "config": {
    "platform": {
      "php": "7.1.3"
    }
  }
}

PHP extensions

We aim to deliver an image that is as lean as possible, built for running Composer only. Sometimes dependencies or Composer scripts require the availability of certain PHP extensions.

Suggestions:

  • pass the --ignore-platform-reqs and / or --no-scripts flags to install or update:

    $ docker run --rm --interactive --tty \
  --volume $PWD:/app \
  composer install --ignore-platform-reqs --no-scripts

  • create your own buid image and install Composer inside it.

    Note: Docker 17.05 introduced multi-stage builds, simplifying this enormously:

    COPY --from=composer /usr/bin/composer /usr/bin/composer

License

View license information for the software contained in this image.

As with all Docker images, these likely also contain other software which may be under other licenses (such as Bash, etc from the base distribution, along with any direct or indirect dependencies of the primary software being contained).

Some additional license information which was able to be auto-detected might be found in the repo-info repository’s composer/ directory.

As for any pre-built image usage, it is the image user’s responsibility to ensure that any use of this image complies with any relevant licenses for all software contained within.

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