Fixed PHP version to 8.1 for older composer versions

[InvensoGroup]

composer:2.3 and composer:2.4 are now fixed to PHP 8.1

base container php:8-alpine is updated to latest PHP version 8.3 which is not yet supported by all packages
use fixed PHP version for older composer version for compatibility

[alcohol]

Is there a reason you went for 8.1 instead of 8.2 ?

[alcohol]

Actually, this change is not necessary. Composer (even the older versions) works just fine on 8.3

[InvensoGroup]

Hi, the reason I raised this pull request is that PHP:8-apline was updated to version 8.3

We use the composer as a build only (standalone) without installing it in the production container

After the update we encountered issues because our source code is supporting PHP 8.1
Since composer 2.3 and 2.4 are older versions and PHP8.3 was not out by that time I was thinking it could be fixed to older versions of PHP

If PHP8.3 is required users can use the latest composer container

I've put a code example below to show how we use the containers
We first build with composer and than copy the vendor to the production container without having composer in the production build.

FROM composer:2 AS build

RUN set -eux; \
  composer dump-autoload --classmap-authoritative --no-dev; \
  composer install --prefer-dist --no-dev --no-scripts --no-progress --ignore-platform-req=ext-xdebug; \
  composer clear-cache; 



FROM php:8.1 AS production

WORKDIR /srv
COPY --from=build /srv/vensor/ ./vendor

[alcohol]

Please read https://github.com/docker-library/docs/tree/master/composer#troubleshooting

[alcohol]

You could do the following:

FROM php:8.1 AS build

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

RUN set -eux; \
  composer dump-autoload --classmap-authoritative --no-dev; \
  composer install --prefer-dist --no-dev --no-scripts --no-progress --ignore-platform-req=ext-xdebug; \
  composer clear-cache; 

FROM php:8.1 AS production

WORKDIR /srv
COPY --from=build /srv/vendor/ ./vendor