Extensions are not getting installed

[Phillip85]

hi,

when I try to add some PHP extensions, it looks like they are not getting installed:

ARG PHP_EXTENSIONS="xdebug ldap gd"
ARG APACHE_EXTENSIONS="ldap authnz_ldap rewrite ssl"
ARG APACHE_DOCUMENT_ROOT=public/

ARG SSH_PRIVATE_KEY="xx"
ARG SSH_KNOWN_HOSTS="xx"

FROM thecodingmachine/php:8.0-v4-apache-node14

RUN echo "$SSH_KNOWN_HOSTS" >> ~/.ssh/known_hosts
RUN echo "$SSH_PRIVATE_KEY" >> ~/.ssh/id_rsa

COPY . /var/www/html

RUN composer install

Composer says that xdebug and gd is not installed:

Step 10/12 : RUN composer install
 ---> Running in abde1d93b4f5
Installing dependencies from lock file (including require-dev)
Verifying lock file contents can be installed on current platform.
Your lock file does not contain a compatible set of packages. Please run composer update.

  Problem 1
    - Root composer.json requires PHP extension ext-xdebug * but it is missing from your system. Install or enable PHP's xdebug extension.
  Problem 2
    - phpoffice/phpspreadsheet is locked to version 1.15.0 and an update of this package was not requested.
    - phpoffice/phpspreadsheet 1.15.0 requires ext-gd * -> it is missing from your system. Install or enable PHP's gd extension.

[Phillip85]

      PHP_EXTENSION_XDEBUG: 1
      PHP_EXTENSION_GD: 1

via docker-compose.yml works

[robjuz]

ARG PHP_EXTENSIONS="xdebug ldap gd"
only work for slim images

when using the normal (fat) image, use env variables to enable extensions

ARG SSH_PRIVATE_KEY="xx"
ARG SSH_KNOWN_HOSTS="xx"

FROM thecodingmachine/php:8.0-v4-apache-node14

ENV PHP_EXTENSIONS="xdebug ldap gd" \
    APACHE_EXTENSIONS="ldap authnz_ldap rewrite ssl"


RUN echo "$SSH_KNOWN_HOSTS" >> ~/.ssh/known_hosts
RUN echo "$SSH_PRIVATE_KEY" >> ~/.ssh/id_rsa

COPY . /var/www/html

RUN composer install