Multi-User Docker-based Server Management

#!/bin/bash

# Default values if variables aren't passed
USER_UID=${HOST_UID:-1000}
USER_GID=${HOST_GID:-1000}
USER_NAME=${USERNAME:-labuser}

echo "Configuring container for $USER_NAME (UID: $USER_UID, GID: $USER_GID)"

# 1. Create the group and user to match the host
groupadd -g $USER_GID $USER_NAME 2>/dev/null || echo "Group exists"
useradd -m -u $USER_UID -g $USER_GID -s /bin/bash $USER_NAME 2>/dev/null || echo "User exists"

# 2. Set a default password and give sudo rights
echo "$USER_NAME:password123" | chpasswd
echo "$USER_NAME ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers

# 3. Fix permissions for Conda so the user can manage their own environments
chown -R $USER_NAME:$USER_GID /opt/conda

# 4. Initialize Conda for the new user
sudo -u $USER_NAME /opt/conda/bin/conda init bash

# 5. Start the SSH service in the foreground
exec /usr/sbin/sshd -D

FROM ubuntu:20.04

# Setup APT and Mirrors
RUN rm -rf /etc/apt/apt.conf.d/* && \
    echo 'APT::Get::AllowUnauthenticated "true";' > /etc/apt/apt.conf.d/99force-insecure
RUN echo "deb [trusted=yes] http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse" > /etc/apt/sources.list

# Install Core Tools and SSH
RUN apt-get update && \
    DEBIAN_FRONTEND=noninteractive apt-get install -y --allow-unauthenticated \
    wget ca-certificates bzip2 openssh-server sudo && \
    mkdir /var/run/sshd && \
    apt-get clean

# Install Miniconda
RUN wget --no-check-certificate https://mirrors.tuna.tsinghua.edu.cn/anaconda/miniconda/Miniconda3-py39_4.12.0-Linux-x86_64.sh -O /tmp/miniconda.sh && \
    bash /tmp/miniconda.sh -b -p /opt/conda && \
    rm /tmp/miniconda.sh

ENV PATH="/opt/conda/bin:$PATH"

# Copy the entrypoint script from your host into the image
COPY entrypoint.sh /usr/local/bin/entrypoint.sh
RUN chmod +x /usr/local/bin/entrypoint.sh

EXPOSE 22

# Tell Docker to run our script on startup
ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]

#!/bin/bash

# Usage: ./start_lab.sh <host_username> <external_port>
TARGET_USER=$1
PORT=$2

if [ -z "$TARGET_USER" ] || [ -z "$PORT" ]; then
    echo "Usage: ./start_lab.sh <username> <port>"
    exit 1
fi

# Get IDs from the host system
U_ID=$(id -u $TARGET_USER)
G_ID=$(id -g $TARGET_USER)
U_HOME="/home/$TARGET_USER"

# Ensure the host directory exists
mkdir -p "$U_HOME"

# Change ownership to the target user 
# (This assumes the user exists on the CentOS host with the same name)
chown -R "$TARGET_USER:$TARGET_USER" "$U_HOME"

# Build/Refresh the image (optional, but ensures entrypoint updates are live)
# docker build -t lab_base_image .

docker run -d \
  --name "lab_$TARGET_USER" \
  --restart unless-stopped \
  -e HOST_UID=$U_ID \
  -e HOST_GID=$G_ID \
  -e USERNAME=$TARGET_USER \
  -p "$PORT:22" \
  -v "$U_HOME:/home/$TARGET_USER:z" \
  lab_base_image

echo "----------------------------------------------------"
echo "Container for $TARGET_USER is now LIVE."
echo "Access via: ssh $TARGET_USER@$(hostname -I | awk '{print $1}') -p $PORT"
echo "Work directory mapped to: $U_HOME"
echo "----------------------------------------------------"