simple script to check supported modes for cvmfsexec

scripts/cvmfsexec_check.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+# Copyright (C) 2026 EESSI contributors
+
+echo "CVMFSEXEC Compatibility Check"
+echo "=============================="
+printf "%-40s %s\n" "Feature" "Status"
+echo "--------------------------------------------------------------"
+
+# Check fusermount
+if command -v fusermount &>/dev/null || command -v fusermount3 &>/dev/null; then
+    FUSERMOUNT="YES"
+    printf "%-40s %s\n" "fusermount" "[YES]"
+else
+    FUSERMOUNT="NO"
+    printf "%-40s %s\n" "fusermount" "[NO]"
+fi
+
+# Check user namespaces
+if [ -f /proc/sys/user/max_user_namespaces ]; then
+    MAX_US_NS=$(cat /proc/sys/user/max_user_namespaces)
+    if [ "$MAX_US_NS" -gt 0 ] 2>/dev/null; then
+        USER_NS="YES"
+        printf "%-40s %s\n" "User namespaces enabled" "[YES]"
+    else
+        USER_NS="NO"
+        printf "%-40s %s\n" "User namespaces enabled" "[NO]"
+    fi
+else
+    USER_NS="NO"
+    printf "%-40s %s\n" "User namespaces enabled" "[NO]"
+fi
+
+# Check unprivileged namespace fuse mounts
+KERNEL=$(uname -r | cut -d. -f1-2)
+if unshare -rm sh -c 'exit 0' &>/dev/null; then
+    UNPRIV_FUSE="YES"
+    printf "%-40s %s\n" "Unprivileged namespace fuse mounts" "[YES]"
+else
+    UNPRIV_FUSE="NO"
+    printf "%-40s %s\n" "Unprivileged namespace fuse mounts" "[NO]"
+fi
+
+# Check for setuid singularity/apptainer
+SETUID_SING="NO"
+for cmd in singularity apptainer; do
+    if command -v $cmd &>/dev/null; then
+        VERSION=$($cmd --version 2>/dev/null | grep -oP '\d+\.\d+' | head -1)
+        BIN=$(which $cmd)
+        if [ -u "$BIN" ] || [ -u "/usr/libexec/$cmd/bin/starter-setuid" ] 2>/dev/null; then
+            SETUID_SING="YES ($cmd $VERSION)"
+            break
+        fi
+    fi
+done
+printf "%-40s %s\n" "Setuid singularity/apptainer >=3.4" "[$SETUID_SING]"
+
+echo ""
+echo "Supported Modes:"
+echo "--------------------------------------------------------------"
+
+if [ "$FUSERMOUNT" = "YES" ]; then
+    echo "Mode 1: mountrepo/umountrepo (with container bindmount)"
+fi
+
+if [ "$FUSERMOUNT" = "YES" ] && [ "$USER_NS" = "YES" ] && [ "$UNPRIV_FUSE" = "NO" ]; then
+    echo "Mode 2: cvmfsexec (user namespaces, no unpriv fuse)"
+fi
+
+if [ "$UNPRIV_FUSE" = "YES" ]; then
+    echo "Mode 3: cvmfsexec (unprivileged namespace fuse mounts) * BEST"
+fi
+
+if [ "$SETUID_SING" != "NO" ]; then
+    echo "Mode 4: singcvmfs (setuid singularity/apptainer)"
+fi