I got memory lack error in docker installing laravel plugin

Hello, Trying to add new package in laravel 7 under docker I got memory lack error :

# composer require nunomaduro/phpinsights --dev
Using version ^1.14 for nunomaduro/phpinsights
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)

Fatal error: Allowed memory size of 1610612736 bytes exhausted (tried to allocate 4096 bytes) in phar:///usr/local/bin/composer/src/Composer/DependencyResolver/Solver.php on line 223

Check https://getcomposer.org/doc/articles/troubleshooting.md#memory-limit-errors for more info on how to handle out of memory errors.

But in the console I see a lot of memory allowed:

root@d6001829f99f:/var/www/hostels3_docker_root# free
              total        used        free      shared  buff/cache   available
Mem:        8085252     5778240     1520788       86808      786224     1956736
Swap:       2104476     2026072       78404

In the php info I see :

memory_limit	2048M	128M

In __DOCKER/web/virtualhost.conf I have parameter :

	php_value  memory_limit  2048M

and

Configuration File (php.ini) Path	/usr/local/etc/php

but trying to open php.ini with command :

nano /usr/local/etc/php.ini

nothing was found. Seems this file is virtual ?

Also I know that (when using lamp) for console commands php cli must be configured. I tried to install php7.3-cli in my __DOCKER/web/Dockerfile.yml :

 RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer

  RUN  docker-php-ext-install gd pdo pdo_mysql zip gmp bcmath pcntl ldap sysvmsg exif php7.3-cli \
&& a2enmod rewrite

COPY virtualhost.conf /etc/apache2/sites-enabled/000-default.conf

But I got error that php7.3-cli is not found.

In which way can I fix memory lack I have ?

In my hosting kubuntu 18 I have 8GiB of memory :

$ lsb_release -d; uname -r; uname -i
Description:    Ubuntu 18.04.4 LTS
4.15.0-112-generic
x86_64
$ free
              total        used        free      shared  buff/cache   available
Mem:        8085252     5623840      141952      110116     2319460     2073288
Swap:       2104476      302848     1801628

Thanks!