PHP 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.

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 Docker image
• Simple to use
• Separation of development and production

Cons:

• When your application requires additional PHP extensions, or is using the scripts defined in the composer.json file, you’ll either need to install them in this additional Composer image or pass the --ignore-platform-reqs and --no-scripts options and run scripts separately.

Quick usage:

docker run -it --rm -v `pwd`:/app composer install

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.

Composer installation in general requires several PHP extensions installed:

• phar
• json
• iconv or mbstring
• openssl
• zip
• zlib

and few system packages, depending on what version system you will use:

• curl
• git
• subversion
• openssh
• openssl
• mercurial

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 -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 or use Docker build arguments

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:

FROM php:7.2

ARG APP_ENV=prod

RUN if [ ${APP_ENV} = "dev" ]; then \
        php -r "readfile('http://getcomposer.org/installer');" | php -- --install-dir=/usr/bin/ --filename=composer; \
    fi

You can set the build arguments in the Docker Compose files and manage how the image is build for each of your environment:

# docker-compose.dev.yaml
version: '3.4'

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

PHP.earth Docker images

PHP.earth Docker images come with optional Composer package which also includes all required PHP extensions dependencies.

For Alpine Linux there is a composer package available:

FROM phpearth/php:7.2-nginx

RUN apk add --no-cache composer

Prestissimo Composer plugin

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

FROM phpearth/php:7.2-nginx

ARG APP_ENV=prod

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