feat(docker): introduce slim.sh for safe image cleanup and run it during build

- add verbose distro-aware cleanup script (apk/apt/pacman/dnf/yum)
- remove package manager caches, logs, tmp and user caches
- keep runtime-critical files untouched
- execute cleanup during image build to reduce final size

https://chatgpt.com/share/696f4ab6-fae8-800f-9a46-e73eb8317791

Dockerfile

@@ -24,6 +24,12 @@ COPY scripts/installation/ scripts/installation/
 # Install distro-specific build dependencies (including make)
 RUN bash scripts/installation/dependencies.sh
 
+# ------------------------------------------------------------
+# Image cleanup (reduce final size)
+# ------------------------------------------------------------
+COPY scripts/docker/slim.sh /usr/local/bin/slim.sh
+RUN chmod +x /usr/local/bin/slim.sh && /usr/local/bin/slim.sh
+
 # Virgin default
 CMD ["bash"]
 
@@ -52,4 +58,10 @@ COPY scripts/docker/entry.sh /usr/local/bin/docker-entry.sh
 
 WORKDIR /opt/src/pkgmgr
 ENTRYPOINT ["/usr/local/bin/docker-entry.sh"]
+
+# ------------------------------------------------------------
+# Image cleanup (reduce final size)
+# ------------------------------------------------------------
+RUN /usr/local/bin/slim.sh
+
 CMD ["pkgmgr", "--help"]

scripts/docker/slim.sh

@@ -0,0 +1,130 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+log()  { echo "[cleanup] $*"; }
+warn() { echo "[cleanup][WARN] $*" >&2; }
+
+MODE="${MODE:-safe}" # safe | aggressive
+# safe: caches/logs/tmp only
+# aggressive: safe + docs/man/info (optional)
+
+ID="unknown"
+if [ -f /etc/os-release ]; then
+  # shellcheck disable=SC1091
+  . /etc/os-release
+  ID="${ID:-unknown}"
+fi
+
+log "Starting image cleanup"
+log "Mode: ${MODE}"
+log "Detected OS: ${ID}"
+
+# ------------------------------------------------------------
+# Package manager caches (SAFE)
+# ------------------------------------------------------------
+case "${ID}" in
+  alpine)
+    log "Cleaning apk cache"
+    if [ -d /var/cache/apk ]; then
+      du -sh /var/cache/apk || true
+      rm -rvf /var/cache/apk/* || true
+    else
+      log "apk cache directory not present (already clean)"
+    fi
+    ;;
+  arch)
+    log "Cleaning pacman cache"
+    du -sh /var/cache/pacman/pkg 2>/dev/null || true
+    pacman -Scc --noconfirm || true
+    rm -rvf /var/cache/pacman/pkg/* || true
+    ;;
+  debian|ubuntu)
+    log "Cleaning apt cache"
+    du -sh /var/lib/apt/lists 2>/dev/null || true
+    apt-get clean || true
+    rm -rvf /var/lib/apt/lists/* || true
+    ;;
+  fedora)
+    log "Cleaning dnf cache"
+    du -sh /var/cache/dnf 2>/dev/null || true
+    dnf clean all || true
+    rm -rvf /var/cache/dnf/* || true
+    ;;
+  centos|rhel)
+    log "Cleaning yum/dnf cache"
+    du -sh /var/cache/yum /var/cache/dnf 2>/dev/null || true
+    (command -v dnf >/dev/null 2>&1 && dnf clean all) || true
+    (command -v yum >/dev/null 2>&1 && yum clean all) || true
+    rm -rvf /var/cache/yum/* /var/cache/dnf/* || true
+    ;;
+  *)
+    warn "Unknown distro '${ID}' — skipping package manager cleanup"
+    ;;
+esac
+
+# ------------------------------------------------------------
+# Python caches (SAFE)
+# ------------------------------------------------------------
+log "Cleaning pip cache"
+du -sh /root/.cache/pip 2>/dev/null || true
+rm -rvf /root/.cache/pip 2>/dev/null || true
+rm -rvf /home/*/.cache/pip 2>/dev/null || true
+
+log "Cleaning __pycache__ directories"
+find /opt /usr /root /home -type d -name "__pycache__" -print -prune 2>/dev/null || true
+find /opt /usr /root /home -type d -name "__pycache__" -prune -exec rm -rvf {} + 2>/dev/null || true
+
+# ------------------------------------------------------------
+# Logs (SAFE)
+# ------------------------------------------------------------
+log "Truncating log files (keeping paths intact)"
+if [ -d /var/log ]; then
+  find /var/log -type f -name "*.log" -print 2>/dev/null || true
+  find /var/log -type f -name "*.log" -exec sh -lc ': > "$1" 2>/dev/null || true' _ {} \; 2>/dev/null || true
+  
+  find /var/log -type f -name "*.out" -print 2>/dev/null || true
+  find /var/log -type f -name "*.out" -exec sh -lc ': > "$1" 2>/dev/null || true' _ {} \; 2>/dev/null || true
+fi
+
+if command -v journalctl >/dev/null 2>&1; then
+  log "Vacuuming journald logs"
+  journalctl --disk-usage || true
+  journalctl --vacuum-size=10M || true
+  journalctl --vacuum-time=1s || true
+  journalctl --disk-usage || true
+else
+  log "journald not present (skipping)"
+fi
+
+# ------------------------------------------------------------
+# Temporary files (SAFE)
+# ------------------------------------------------------------
+log "Cleaning temporary directories"
+if [ -d /tmp ]; then
+  du -sh /tmp 2>/dev/null || true
+  rm -rvf /tmp/* || true
+fi
+
+if [ -d /var/tmp ]; then
+  du -sh /var/tmp 2>/dev/null || true
+  rm -rvf /var/tmp/* || true
+fi
+
+# ------------------------------------------------------------
+# Generic caches (SAFE)
+# ------------------------------------------------------------
+log "Cleaning generic caches"
+du -sh /root/.cache 2>/dev/null || true
+rm -rvf /root/.cache/* 2>/dev/null || true
+rm -rvf /home/*/.cache/* 2>/dev/null || true
+
+# ------------------------------------------------------------
+# Optional aggressive extras (still safe for runtime)
+# ------------------------------------------------------------
+if [[ "${MODE}" == "aggressive" ]]; then
+  log "Aggressive mode enabled: removing docs/man/info"
+  du -sh /usr/share/doc /usr/share/man /usr/share/info 2>/dev/null || true
+  rm -rvf /usr/share/doc/* /usr/share/man/* /usr/share/info/* 2>/dev/null || true
+fi
+
+log "Cleanup finished successfully"