PHP Dockerfile with composer target

Dockerfile

FROM php:7.2.10-fpm-alpine3.8 AS base

# Stuff needed in all layers
RUN apk add --no-cache gettext fcgi icu-dev 
RUN docker-php-ext-install bcmath 

FROM base AS dependencies

COPY --from=composer:1.7 /usr/bin/composer /usr/bin/composer
COPY composer.json /app/composer.json
WORKDIR /app
RUN composer install -a -o --no-dev

FROM base as prod

# Assumes /vendor is in .dockerignore
COPY --from=dependencies /app/vendor /app/vendor
COPY . /app/