docker: Run container with its own network namespace

For normal operation, there is no need for the container to run
in the host network environment or to have access to the users
X Session.

To accomodate usecases which need this, there is now a `TOPOTEST_OPTIONS`
environment variable to provide additional options to the docker run
command.

Signed-off-by: Christian Franke <chris@opensourcerouting.org>

tests/topotests/docker/motd.txt

@@ -14,7 +14,3 @@ Here are some useful tips:
 
 * The topotests log directory can be found on your host machine on
   `/tmp/topotests_logs`.
-
-* You may open an `xterm` inside the container. We do our best to detect
-  the X session on your host machine
-

tests/topotests/docker/topotests_run.sh

@@ -22,30 +22,113 @@
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
+set -e
 
-# Source folders
-FRR_DIR=$HOME/src/frr
-TOPOTESTS_DIR=$HOME/src/topotests
+if [[ "$1" = "-h" ]] || [[ "$1" = "--help" ]]; then
+	cat >&2 <<-EOF
 
+	This script runs the FRRouting topotests on the FRR tree
+	in the current working directory.
 
-#
-# Script begin
-#
-CMD=$1
-if [ -z $1 ]; then
-  CMD=bash
+	Usage: $0 [args...]
+
+	Its behavior can be modified by the following environment variables:
+
+	TOPOTEST_AUTOLOAD       If set to 1, the script will try to load necessary
+	                        kernel modules without asking for confirmation first.
+
+	TOPOTEST_BUILDCACHE     Docker volume used for caching multiple FRR builds
+	                        over container runs. By default a
+	                        \`topotest-buildcache\` volume will be created for
+	                        that purpose.
+
+	TOPOTEST_FRR            If set, don't test the FRR in the current working
+	                        directory, but the one at the given path.
+
+	TOPOTEST_LOGS           If set, don't use \`/tmp/topotest_logs\` directory
+	                        but use the provided path instead.
+
+	TOPOTEST_OPTIONS        These options are appended to the docker-run
+	                        command for starting the tests.
+
+	TOPOTEST_PATH           If set, don't use the tests built into the image
+	                        but the ones at the given path.
+
+	To get information about the commands available inside of the container,
+	run \`$0 help\`.
+	EOF
+	exit 1
 fi
 
-docker run --rm -ti \
-  -v "/lib/modules:/lib/modules" \
-  -v "/tmp/topotests_logs:/tmp" \
-  -v "$FRR_DIR:/root/frr:ro" \
-  -v "$TOPOTESTS_DIR:/root/topotests:ro" \
-  -v "/tmp/.X11-unix:/tmp/.X11-unix" \
-  -v "$HOME/.Xauthority:/root/.Xauthority" \
-  -e DISPLAY=$DISPLAY \
-  --net=host \
-  --privileged \
-  topotests
+#
+# These two modules are needed to run the MPLS tests.
+# They are often not automatically loaded.
+#
+# We cannot load them from the container since we don't
+# have host kernel modules available there. If we load
+# them from the host however, they can be used just fine.
+#
 
-exit 0
+for module in mpls-router mpls-iptunnel; do
+	if modprobe -n $module 2> /dev/null; then
+		:
+	else
+		# If the module doesn't exist, we cannot do anything about it
+		continue
+	fi
+
+	if [ $(grep -c ${module/-/_} /proc/modules) -ne 0 ]; then
+		# If the module is loaded, we don't have to do anything
+		continue
+	fi
+
+	if [ "$TOPOTEST_AUTOLOAD" != "1" ]; then
+		echo "To run all the possible tests, we need to load $module."
+		echo -n "Do you want to proceed? [y/n] "
+		read answer
+		if [ x"$answer" != x"y" ]; then
+			echo "Not loading."
+			continue
+		fi
+	fi
+
+	if [ x"$(whoami)" = x"root" ]; then
+		modprobe $module
+	else
+		sudo modprobe $module
+	fi
+done
+
+if [ -z "$TOPOTEST_LOGS" ]; then
+	mkdir -p /tmp/topotest_logs
+	TOPOTEST_LOGS="/tmp/topotest_logs"
+fi
+
+if [ -z "$TOPOTEST_FRR" ]; then
+	TOPOTEST_FRR="$(pwd)"
+fi
+
+if [ -z "$TOPOTEST_BUILDCACHE" ]; then
+	TOPOTEST_BUILDCACHE=topotest-buildcache
+	docker volume inspect "${TOPOTEST_BUILDCACHE}" &> /dev/null \
+		|| docker volume create "${TOPOTEST_BUILDCACHE}"
+fi
+
+if [ -z "$TOPOTEST_PATH" ]; then
+	docker run --rm -ti \
+		-v "$TOPOTEST_LOGS:/tmp" \
+		-v "$TOPOTEST_FRR:/root/frr:ro" \
+		-v "$TOPOTEST_BUILDCACHE:/root/frr-build" \
+		--privileged \
+		$TOPOTEST_OPTIONS \
+		frrouting/topotests "$@"
+else
+	docker run --rm -ti \
+		-v "$TOPOTEST_LOGS:/tmp" \
+		-v "$TOPOTEST_FRR:/root/frr:ro" \
+		-v "$TOPOTEST_BUILDCACHE:/root/frr-build" \
+		-v "$TOPOTEST_PATH:/root/topotests:ro" \
+		--privileged \
+		$TOPOTEST_OPTIONS \
+		frrouting/topotests "$@"
+fi