Wrong PHP version used when installing composer with Alpine's apk command

Question

I've got a docker image running 8.0 and want to upgrade to 8.1. I have updated the image to run with PHP 8.1 and want to update the dependencies in it.

The new image derives from php:8.1.1-fpm-alpine3.15

I've updated the composer.json and changed require.php to ^8.1 but ran into the following message when running composer upgrade:

Root composer.json requires php ^8.1 but your php version (8.0.14) does not satisfy that requirement.

What I find dazzling is that the composer incorrectly identifies PHP version. I used two commands to determine that:

which php # returns only /usr/local/bin/php
/usr/local/bin/php -v # returns PHP 8.1.1 (cli) (built: Dec 18 2021 01:38:53) (NTS)

So far I've tried:

• Checking php -v
• Clearing composer cache
• Rebuilding image

Composer version 2.1.12 2021-11-09 16:02:04

composer check-platform-reqs | grep php
# returns:
# ...
# php                   8.0.14  project/name requires php (^8.1)                   failed  

All of the commands above (excluding docker commands) are being ran in the container

Dockerfile:

FROM php:8.1.1-fpm-alpine3.15

ENV TZ=Europe/London

# Install php lib deps
RUN apk update && apk upgrade
RUN apk add --update libzip-dev \
        zip \
        unzip \
        libpng-dev \
        nginx \
        supervisor \
        git \
        curl \
        shadow \
        composer \
        yarn && rm -rf /var/cache/apk/*

RUN usermod -u 1000 www-data
RUN usermod -d /var/www www-data

RUN mkdir -p /run/nginx && chown www-data:www-data /run/nginx

ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.1.9/supercronic-linux-amd64 \
    SUPERCRONIC=supercronic-linux-amd64 \
    SUPERCRONIC_SHA1SUM=5ddf8ea26b56d4a7ff6faecdd8966610d5cb9d85

RUN curl -fsSLO "$SUPERCRONIC_URL" \
 && echo "${SUPERCRONIC_SHA1SUM}  ${SUPERCRONIC}" | sha1sum -c - \
 && chmod +x "$SUPERCRONIC" \
 && mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" \
 && ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic

# Install and enable php extensions
RUN docker-php-ext-install sockets mysqli pdo_mysql zip gd bcmath > /dev/null

ARG ENV="development"
# Xdebug install
RUN if [ $ENV = "development" ] ; then \
        apk add --no-cache $PHPIZE_DEPS; \
        pecl install xdebug > /dev/null; \
        docker-php-ext-enable xdebug; \
        echo "error_reporting = E_ALL" >> /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini; \
        echo "display_startup_errors = On" >> /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini; \
        echo "display_errors = On" >> /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini; \
        echo "xdebug.remote_enable=1" >> /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini; \
    fi ;

# Setup working directory
RUN chown -R www-data:www-data /var/www
WORKDIR /var/www
USER www-data


# Install dependencies
#RUN if [ $ENV = "development" ] ; then \
##        composer install -n; \
#    else \
##        composer install -n --no-dev; \
#    fi ;

# Generate doctrine proxies

Answer 1

Huh. This surprised me a bit.

composer is correctly reporting the PHP version it's using. The problem is that it's not using the "correct" PHP interpreter.

The issue arises because of how you are installing composer.

Apparently by doing apk add composer another version of PHP gets installed (you can find it on /usr/bin/php8, this is the one on version 8.0.14).

Instead of letting apk install composer for you, you can do it manually. There is nothing much to install it in any case, no need to go through the package manager. Particularly since PHP has not been installed via the package manager on your base image.

I've just removed the line containing composer from the apk add --update command, and added this somewhere below:

 RUN php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');" && \
     php -r "if (hash_file('sha384', 'composer-setup.php') === '906a84df04cea2aa72f40b5f787e49f22d4c2f19492ac310e8cba5b96ac8b64115ac402c8cd292b8a03482574915d1a8') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;" && \
     php composer-setup.php && \
     php -r "unlink('composer-setup.php');" && \
     mv composer.phar /usr/local/bin/composer;

You could also simply download the latest composer PHAR file from here, and add it to the image, depending on how you want to go.

Now there is a single PHP version, and composer will run correctly on PHP 8.1.1.