Improve file filtering in UBI docker image

Signed-off-by: faizanahmad055 <faizan.ahmad55@outlook.com>

Author: faizanahmad055

Dockerfile.ubi

@@ -23,19 +23,29 @@ COPY ubi-build-files-${TARGETARCH}.txt /tmp
 # Filter existing files and exclude temporary entitlement files that may be removed during build
 RUN set -e && \
     # Filter files that actually exist (files, directories, or symlinks)
+    # This ensures we only copy files that are present, avoiding "Cannot stat" errors
     while IFS= read -r file; do \
       [ -n "$file" ] && ([ -e "$file" ] || [ -L "$file" ]) && echo "$file"; \
     done < /tmp/ubi-build-files-${TARGETARCH}.txt > /tmp/existing-files.txt && \
-    # Create tarball if we have files to archive
-    if [ -s /tmp/existing-files.txt ]; then \
-      tar -chf /tmp/files.tar \
-        --exclude='etc/pki/entitlement-host*' \
-        -T /tmp/existing-files.txt 2>&1 | grep -vE "(File removed before we read it|Cannot stat)" || true; \
-      # Extract only if tarball was created successfully
-      if [ -f /tmp/files.tar ]; then \
-        tar -xf /tmp/files.tar -C /image/ && \
-        rm -f /tmp/files.tar; \
-      fi; \
+    # Verify we have files to copy (fail if list is empty to catch configuration issues)
+    if [ ! -s /tmp/existing-files.txt ]; then \
+      echo "ERROR: No files found to copy from ubi-build-files-${TARGETARCH}.txt" >&2; \
+      echo "This indicates the base image may be missing required files or the file list is incorrect." >&2; \
+      echo "Expected files from ubi-build-files-${TARGETARCH}.txt:" >&2; \
+      cat /tmp/ubi-build-files-${TARGETARCH}.txt >&2; \
+      exit 1; \
+    fi && \
+    # Create tarball, excluding only temporary entitlement files (safe to exclude)
+    # Note: --exclude only affects files within directories being archived, not the directories themselves
+    tar -chf /tmp/files.tar \
+      --exclude='etc/pki/entitlement-host*' \
+      -T /tmp/existing-files.txt 2>&1 | grep -vE "(File removed before we read it|Cannot stat)" || true; \
+    # Extract tarball (critical files like libc.so.6, ld-linux, etc/ssl/certs are included)
+    if [ -f /tmp/files.tar ]; then \
+      tar -xf /tmp/files.tar -C /image/ && \
+      rm -f /tmp/files.tar; \
+    else \
+      echo "WARNING: Tarball was not created, but continuing..." >&2; \
     fi && \
     # Clean up temporary file list
     rm -f /tmp/existing-files.txt