Minor changes to base Dockerfile:

- Using debian:12-slim instead of base image
- Added netcat-openbsd in installed packages which is needed for healthcheck
- Added HADOOP_OPTS env for resourcemanager container
- Changed env USER=hdoop from USER=root
- Added useradd anc chown commands for hdoop user

base/Dockerfile

@@ -1,5 +1,5 @@
 # Base image: Debian-12
-FROM debian:12
+FROM debian:12-slim
 
 # Update local package index, upgrade packages and install required packages. 
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
@@ -7,6 +7,7 @@ RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-ins
 	net-tools \
 	curl \
 	gnupg \
+  netcat-openbsd \
 	&& rm -rf /var/lib/apt/lists/*
       
 # Set Java env
@@ -39,15 +40,33 @@ RUN mkdir /opt/hadoop-$HADOOP_VERSION/logs /hadoop-data
 # Set env
 ENV HADOOP_HOME=/opt/hadoop-$HADOOP_VERSION
 ENV HADOOP_CONF_DIR=/etc/hadoop
+ENV HADOOP_OPTS="--add-opens java.base/java.lang=ALL-UNNAMED"
 ENV MULTIHOMED_NETWORK=1
-ENV USER=root
+ENV USER=hdoop
 ENV PATH $HADOOP_HOME/bin/:$PATH
 
+# Ensure required config files exist
+# RUN mkdir -p /etc/hadoop && \
+#     echo "<configuration></configuration>" > /etc/hadoop/core-site.xml && \
+#     echo "<configuration></configuration>" > /etc/hadoop/hdfs-site.xml && \
+#     echo "<configuration></configuration>" > /etc/hadoop/yarn-site.xml && \
+#     echo "<configuration></configuration>" > /etc/hadoop/mapred-site.xml && \
+#     echo "<configuration></configuration>" > /etc/hadoop/httpfs-site.xml && \
+#     echo "<configuration></configuration>" > /etc/hadoop/kms-site.xml
+
+# Create non-root user
+RUN useradd -m -s /bin/bash hdoop
+
 # Copy entrypoint.sh to container
 ADD entrypoint.sh /entrypoint.sh
 
+# Set ownership for Hadoop dirs
+RUN chown -R hdoop:hdoop /opt/hadoop-$HADOOP_VERSION /etc/hadoop /hadoop-data
+
 # Make entrypoint.sh executable
 RUN chmod a+x /entrypoint.sh
 
+USER hdoop
+
 # Specify entrypoint
 ENTRYPOINT ["/entrypoint.sh"]