composer.md

Composer with Docker development

Composer is a de-facto standard for managing PHP packages. Good practice however is to not include it in the production Docker images. By default these images include a helper installation script install-composer so you can easily install Composer or install it from the particular Linux repository.

Let's first take a look at how to use Composer with Docker in general. There are some established best practices:

1. Official Docker Composer image

• Docker Composer - Official Docker image with Composer.

Pros:

• Official Composer image
• Simple to use
• Easy separation of development and production

Cons:

• It is a separate Docker image so if your application requires additional PHP extensions, or use the scripts defined in the composer.json file, you'll either need to install those also for this additional Composer image or pass the --ignore-platform-reqs and --no-scripts and manage scripts separately.

2. Custom installation

You can also simply install Composer per project basis on your own in your Dockerfile:

RUN php -r "readfile('http://getcomposer.org/installer');" | php -- --install-dir=/usr/bin/ --filename=composer

If you'll need to install PHP packages from sources instead of zip archives you will also need to install version control system such as Git.

RUN apt-get update && apt-get -y --no-install-recommends install git \
    && php -r "readfile('http://getcomposer.org/installer');" | php -- --install-dir=/usr/bin/ --filename=composer \
    && rm -rf /var/lib/apt/lists/*

Composer can be then used in the following ways:

docker run -it --rm --name composer -v "$PWD":/usr/src/myapp -w /usr/src/myapp php-app composer

With Docker Compose

docker-compose run --rm -w /var/www/app app composer

Pros:

Advantage of custom installation per project is that Composer is running with the same PHP installation as your application and can pass the PHP extensions checkings.

Cons:

• Composer is present also in production and to have separate production image you'll need to create more than one Dockerfile for application. Follow chapter 3 how to solve this case.

3. Docker build arguments

When building production images, you can avoid adding Composer in your image with build arguments. The following example uses Docker build arguments and the provided Composer package in PHP.earth Alpine repository:

FROM phpearth/php:7.1-nginx

ARG APP_ENV=prod

RUN if [ ${APP_ENV} = "dev" ]; then \
        apk add --no-cache git openssh php7.1-composer; \
    fi

You can set the build arguments in the Docker Compose files. For example:

version: '3.3'

services:
  app:
    volumes:
      - ../:/var/www/app
    build:
      args:
        - APP_ENV=dev
    ports:
      - 80:80

Prestissimo Composer plugin

Prestissimo is a Composer plugin for faster parallel downloading of PHP packages.

FROM phpearth/php:7.1-nginx

ARG APP_ENV=prod

RUN if [ ${APP_ENV} = "dev" ]; then \
        apk add --no-cache git openssh php7.1-composer \
        && composer global require hirak/prestissimo; \
    fi