Changed from Ubuntu 22 to Debian 12

dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:22.04
+FROM debian:12
 
 # set container hostname and DN in case we don't set it on the docker build/run command
 ARG LDAP_HOST=example.com
@@ -6,20 +6,25 @@ ENV LDAP_HOST=${LDAP_HOST}
 
 # set non-interactive TERM for docker
 ENV DEBIAN_FRONTEND=noninteractive
-#──────────────────────────────────────────────────────────────
-# install OpenLDAP, ldap-utils, and packages needed for ldapdock to work
-#──────────────────────────────────────────────────────────────
-RUN apt-get update && apt-get install -y --no-install-recommends \
-slapd ldap-utils gnutls-bin ssl-cert ca-certificates schema2ldif vim mc && apt-get clean
 
 #──────────────────────────────────────────────────────────────
-# APACHE && PHP && neccesary related software
+# Install ALL necessary packages in a single run for minimal image size
 #──────────────────────────────────────────────────────────────
-RUN apt-get update && apt-get install -y --no-install-recommends \
-    apache2 \
-    php libapache2-mod-php \
-    php-ldap php-mbstring php-xml php-curl php-intl wget \
-    && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get install -y --no-install-recommends gnupg lsb-release ca-certificates apt-transport-https software-properties-common wget \
+    # Add the repository for older PHP versions
+    && wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg \
+    && echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list \
+    # Update again to fetch packages from the new repository
+    && apt-get update \
+    # Install all packages, specifying PHP 8.1
+    && apt-get install -y --no-install-recommends \
+        apt-utils \
+        slapd ldap-utils gnutls-bin ssl-cert schema2ldif vim mc \
+        apache2 \
+        php8.1 libapache2-mod-php8.1 \
+        php8.1-ldap php8.1-mbstring php8.1-xml php8.1-curl php8.1-intl \
+    # Clean up APT caches to reduce image size
+    && apt-get clean && rm -rf /var/lib/apt/lists/*
 
 # Enable required Apache modules
 RUN a2enmod rewrite headers ssl