Compile ovs for ovsfw to avoid ovs-vswitchd core dumps

Change-Id: I750224f7495aa46634bec1211599953cbbd4d1df
Closes-bug: #1742863
(cherry picked from commit 46d693530b)

TESTING.rst

@@ -321,9 +321,10 @@ present in current Ubuntu Xenial 16.04 kernel. Kernel was fixed with this
 `commit <https://github.com/torvalds/linux/commit/bbec7802c6948c8626b71a4fe31283cb4691c358>`_
 and backported with this
 `openvswitch commit <https://github.com/openvswitch/ovs/commit/b1c74f35273122db4ce2728a70fd34b98f525434>`_.
-Due to kernel compatibility, Ubuntu Trusty (Mitaka release) uses openvswitch
-version 2.5.1. Ubuntu Xenial jobs use 2.6.1. Both versions contain fixes for
-local VXLAN tunneling.
+
+Currently we compile openvswitch userland and kernel module from source for
+the ovsfw tempest job on the gate. This is to avoid ovs-vswitchd core dumps.
+See the gate_hook.sh comments for details.
 
 API Tests
 ~~~~~~~~~

neutron/tests/contrib/gate_hook.sh

@@ -89,6 +89,19 @@ case $VENV in
     ;;
 
 "api"|"api-pecan"|"full-ovsfw"|"full-pecan"|"dsvm-scenario-ovs"|"dsvm-scenario-linuxbridge")
+    if [[ "$VENV" =~ "full-ovsfw" ]]; then
+        source $DEVSTACK_PATH/functions
+        source $NEUTRON_PATH/devstack/lib/ovs
+        # In the above case, this is done in configure_for_func_testing.sh
+        DEST=${GATE_DEST:-$DEST}
+        # The OVS_BRANCH variable is used by git checkout. In the case below,
+        # we use v2.8 branch that contains a fix for ovs-vswtichd crash.
+        # NOTE(toshii): Replace with a release tag when one is available.
+        # See commit 3a23430b573e8ab (on the ovs repo).
+        OVS_BRANCH="064f8465022856654648b4b8fa11898024316e11"
+        compile_ovs True /usr /var
+    fi
+
     # TODO(ihrachys) consider feeding result of ext-list into tempest.conf
     load_rc_hook api_all_extensions
     if [ "${FLAVOR}" = "dvrskip" ]; then