Add subunit output for total elapsed time

This commit adds a success output for the entire devstack run to the
subunit output. Ideally we wouldn't need this, but because we don't
have timing data for every single operation performed by devstack we
need to do this to track the total duration of the devstack run.

To capture failures this commit adds saving a devstack event when we
trip the exit_trap. This will save a similar result to the stream in
the successful case, but instead mark it as a failure.

This is backported from master branch to generate subunit result so
d-g can collect it from the new location.

Depends-On: Icc7df33e4d73ba6322af38fbdf3aea230f2fcf4d
Depends-On: I97a604ac08797909afc236401281a5d84b98d53f
Change-Id: I07112dde996c3e2c73f5aafc9b73d33d26374633

stack.sh

@@ -46,6 +46,8 @@ if [[ -n "$NOUNSET" ]]; then
     set -o nounset
 fi
 
+# Set start of devstack timestamp
+DEVSTACK_START_TIME=$(date +%s)
 
 # Configuration
 # =============
@@ -458,11 +460,14 @@ function exit_trap {
 
     if [[ $r -ne 0 ]]; then
         echo "Error on exit"
+        generate-subunit $DEVSTACK_START_TIME $SECONDS 'fail' >> ${SUBUNIT_OUTPUT}
         if [[ -z $LOGDIR ]]; then
             $TOP_DIR/tools/worlddump.py
         else
             $TOP_DIR/tools/worlddump.py -d $LOGDIR
         fi
+    else
+        generate-subunit $DEVSTACK_START_TIME $SECONDS >> ${SUBUNIT_OUTPUT}
     fi
 
     exit $r
@@ -684,6 +689,9 @@ if [[ "$OFFLINE" != "True" ]]; then
     PYPI_ALTERNATIVE_URL=${PYPI_ALTERNATIVE_URL:-""} $TOP_DIR/tools/install_pip.sh
 fi
 
+# Install subunit for the subunit output stream
+pip_install_gr os-testr
+
 TRACK_DEPENDS=${TRACK_DEPENDS:-False}
 
 # Install Python packages into a virtualenv so that we can track them

stackrc

@@ -17,6 +17,9 @@ DATA_DIR=${DEST}/data
 # Destination for status files
 SERVICE_DIR=${DEST}/status
 
+# Path for subunit output file
+SUBUNIT_OUTPUT=${DEST}/devstack.subunit
+
 # Determine stack user
 if [[ $EUID -eq 0 ]]; then
     STACK_USER=stack