add composer

Dockerfile

 FROM php:8.1-apache
 RUN docker-php-ext-install mysqli pdo pdo_mysql
-RUN apt-get update -y && apt-get install -y libpng-dev
-RUN apt-get update && \
-    apt-get install -y \
-        zlib1g-dev 
+RUN apt-get update -y && apt-get install -y libpng-dev zlib1g-dev
+RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
 RUN docker-php-ext-install gd
 RUN a2enmod rewrite
 RUN service apache2 restart

docker-compose.yml

@@ -2,12 +2,12 @@ version: '3.1'
 
 services:
   php-apache:
-    container_name: digitepp
+    container_name: base-docker
     build:
       context: .
       dockerfile: Dockerfile
     ports:
-      - 4000:80
+      - 4005:80
     volumes:
       - ./:/var/www/html/
       - ./apache/default.conf:/etc/apache2/sites-enabled/000-default.conf
\ No newline at end of file

index.php

+<?php echo "Hello World"; ?>
\ No newline at end of file