Add basic initial "check-config" script to contrib

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

contrib/check-config.sh

@@ -0,0 +1,102 @@
+#!/usr/bin/env bash
+set -e
+
+# bits of this were adapted from lxc-checkconfig
+# see also https://github.com/lxc/lxc/blob/lxc-1.0.2/src/lxc/lxc-checkconfig.in
+
+: ${CONFIG:=/proc/config.gz}
+: ${GREP:=zgrep}
+
+if [ ! -e "$CONFIG" ]; then
+	echo >&2 "warning: $CONFIG does not exist, searching other paths for kernel config..."
+	if [ -e "/boot/config-$(uname -r)" ]; then
+		CONFIG="/boot/config-$(uname -r)"
+	elif [ -e '/usr/src/linux/.config' ]; then
+		CONFIG='/usr/src/linux/.config'
+	else
+		echo >&2 "error: cannot find kernel config"
+		echo >&2 "  try running this script again, specifying the kernel config:"
+		echo >&2 "    CONFIG=/path/to/kernel/.config $0"
+		exit 1
+	fi
+fi
+
+is_set() {
+	$GREP "CONFIG_$1=[y|m]" $CONFIG > /dev/null
+}
+
+color() {
+	color=
+	prefix=
+	if [ "$1" = 'bold' ]; then
+		prefix='1;'
+		shift
+	fi
+	case "$1" in
+		green) color='32' ;;
+		red)   color='31' ;;
+		gray)  color='30' ;;
+		reset) color='' ;;
+	esac
+	echo -en '\033['"$prefix$color"m
+}
+
+check_flag() {
+	if is_set "$1"; then
+		color green
+		echo -n enabled
+	else
+		color bold red
+		echo -n missing
+	fi
+	color reset
+}
+
+check_flags() {
+	for flag in "$@"; do
+		echo "- CONFIG_$flag: $(check_flag "$flag")"
+	done
+} 
+
+echo
+
+# TODO check that the cgroupfs hierarchy is properly mounted
+
+echo 'Generally Necessary:'
+flags=(
+	NAMESPACES {NET,PID,IPC,UTS}_NS
+	DEVPTS_MULTIPLE_INSTANCES
+	CGROUPS CGROUP_DEVICE
+	MACVLAN VETH BRIDGE
+	IP_NF_TARGET_MASQUERADE NETFILTER_XT_MATCH_{ADDRTYPE,CONNTRACK}
+	NF_NAT NF_NAT_NEEDED
+)
+check_flags "${flags[@]}"
+echo
+
+echo 'Optional Features:'
+flags=(
+	MEMCG_SWAP
+	RESOURCE_COUNTERS
+)
+check_flags "${flags[@]}"
+
+echo '- Storage Drivers:'
+{
+	echo '- "aufs":'
+	check_flags AUFS_FS | sed 's/^/  /'
+	if ! is_set AUFS_FS && grep -q aufs /proc/filesystems; then
+		echo "    $(color bold gray)(note that some kernels include AUFS patches but not the AUFS_FS flag)$(color reset)"
+	fi
+
+	echo '- "btrfs":'
+	check_flags BTRFS_FS | sed 's/^/  /'
+
+	echo '- "devicemapper":'
+	check_flags BLK_DEV_DM DM_THIN_PROVISIONING EXT4_FS | sed 's/^/  /'
+} | sed 's/^/  /'
+echo
+
+#echo 'Potential Future Features:'
+#check_flags USER_NS
+#echo