diff --git a/server/docker-installer.sh b/server/docker-installer.sh
new file mode 100644
index 0000000..1f7abfd
--- /dev/null
+++ b/server/docker-installer.sh
@@ -0,0 +1,186 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Installs Docker Engine + Docker Compose plugin on Ubuntu/Debian or RHEL-like (CentOS/Rocky/Alma).
+# Adds a user to the "docker" group (so they can run docker without sudo).
+#
+# Usage:
+#   sudo ./install-docker.sh
+#   sudo ./install-docker.sh --user username
+#   sudo ./install-docker.sh --user username --no-docker-group
+#
+# Notes:
+# - After adding a user to docker group, they must re-login (or run: newgrp docker).
+
+TARGET_USER=""
+ADD_TO_DOCKER_GROUP="1"
+
+usage() {
+  cat <<'EOF'
+Usage:
+  install-docker.sh [--user <username>] [--no-docker-group]
+
+Options:
+  --user <username>       Add this user to docker group (default: current sudo user if set)
+  --no-docker-group       Do not add any user to docker group
+  -h, --help              Show help
+EOF
+}
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --user)
+      [[ $# -ge 2 ]] || { echo "Missing value for --user" >&2; usage; exit 2; }
+      TARGET_USER="$2"
+      shift 2
+      ;;
+    --no-docker-group)
+      ADD_TO_DOCKER_GROUP="0"
+      shift
+      ;;
+    -h|--help)
+      usage
+      exit 0
+      ;;
+    *)
+      echo "Unknown argument: $1" >&2
+      usage
+      exit 2
+      ;;
+  esac
+done
+
+if [[ "${EUID}" -ne 0 ]]; then
+  echo "Run as root (sudo)." >&2
+  exit 1
+fi
+
+# Default user: the sudo invoker (if any), else empty
+if [[ -z "${TARGET_USER}" && -n "${SUDO_USER:-}" && "${SUDO_USER}" != "root" ]]; then
+  TARGET_USER="${SUDO_USER}"
+fi
+
+if command -v docker >/dev/null 2>&1; then
+  echo "Docker already installed: $(docker --version || true)"
+fi
+
+detect_os() {
+  if [[ -r /etc/os-release ]]; then
+    # shellcheck disable=SC1091
+    . /etc/os-release
+    echo "${ID:-unknown}" "${VERSION_CODENAME:-}" "${VERSION_ID:-}"
+  else
+    echo "unknown" "" ""
+  fi
+}
+
+ID="" CODENAME="" VERSION_ID=""
+read -r ID CODENAME VERSION_ID < <(detect_os)
+
+echo "Detected OS: ID=${ID} CODENAME=${CODENAME} VERSION_ID=${VERSION_ID}"
+
+setup_daemon_json() {
+  mkdir -p /etc/docker
+  if [[ ! -f /etc/docker/daemon.json ]]; then
+    cat > /etc/docker/daemon.json <<'JSON'
+{
+  "log-driver": "json-file",
+  "log-opts": {
+    "max-size": "10m",
+    "max-file": "3"
+  }
+}
+JSON
+    echo "Created /etc/docker/daemon.json (log rotation)."
+  else
+    echo "/etc/docker/daemon.json already exists; leaving as-is."
+  fi
+}
+
+install_debian_ubuntu() {
+  apt-get update
+  apt-get -y install ca-certificates curl gnupg
+
+  install -m 0755 -d /etc/apt/keyrings
+  curl -fsSL https://download.docker.com/linux/${ID}/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+  chmod a+r /etc/apt/keyrings/docker.gpg
+
+  ARCH="$(dpkg --print-architecture)"
+  CODENAME_LOCAL="${CODENAME}"
+  if [[ -z "${CODENAME_LOCAL}" ]]; then
+    CODENAME_LOCAL="$(. /etc/os-release && echo "${VERSION_CODENAME}")"
+  fi
+
+  cat > /etc/apt/sources.list.d/docker.list <<EOF
+deb [arch=${ARCH} signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/${ID} ${CODENAME_LOCAL} stable
+EOF
+
+  apt-get update
+  apt-get -y install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
+}
+
+install_rhel_like() {
+  # Works for: centos/rhel/almalinux/rocky/fedora (docker provides packages for many of these)
+  if command -v dnf >/dev/null 2>&1; then
+    PM="dnf"
+  else
+    PM="yum"
+  fi
+
+  $PM -y install yum-utils ca-certificates curl
+
+  # Repo
+  yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
+
+  $PM -y install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
+}
+
+case "${ID}" in
+  ubuntu|debian)
+    install_debian_ubuntu
+    ;;
+  rhel|centos|fedora|rocky|almalinux)
+    install_rhel_like
+    ;;
+  *)
+    echo "Unsupported OS ID='${ID}'. Supported: ubuntu, debian, centos/rhel/rocky/almalinux/fedora" >&2
+    exit 1
+    ;;
+esac
+
+setup_daemon_json
+
+systemctl enable docker
+systemctl restart docker
+
+# docker group/user permissions
+if ! getent group docker >/dev/null; then
+  groupadd docker || true
+fi
+
+if [[ "${ADD_TO_DOCKER_GROUP}" == "1" && -n "${TARGET_USER}" ]]; then
+  if id "${TARGET_USER}" >/dev/null 2>&1; then
+    usermod -aG docker "${TARGET_USER}"
+    echo "Added user '${TARGET_USER}' to group 'docker'."
+  else
+    echo "User '${TARGET_USER}' not found; skipping docker group assignment." >&2
+  fi
+fi
+
+echo
+echo "=== Installed ==="
+docker --version
+docker compose version
+
+echo
+echo "=== Service status ==="
+systemctl --no-pager --full status docker | sed -n '1,25p' || true
+
+echo
+if [[ "${ADD_TO_DOCKER_GROUP}" == "1" && -n "${TARGET_USER}" ]]; then
+  echo "IMPORTANT: user '${TARGET_USER}' must re-login for docker group to apply."
+  echo "Quick test after relogin: docker run --rm hello-world"
+else
+  echo "To use docker without sudo: add a user to docker group:"
+  echo "  sudo usermod -aG docker <username> && newgrp docker"
+fi
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