Allow running kuryr-libnetwork with uwsgi

scripts/run_kuryr.sh now understands KURYR_USE_UWSGI. If set to "True" (default)
it would attempt to look for uwsgi executable and run kuryr-libnetwork
with it.
Number of spawned threads and processes can be controlled with
KURYR_UWSGI_THREADS and KURYR_UWSGI_PROCESSES env variables.

If uwsgi is not present or KURYR_USE_UWSGI is set to false the script
operates as usual.

Targets bp: deploy-kuryr-libnetwork-api-in-wsgi
Co-Authored-By: Kirill Zaitsev <k.zaitsev@me.com>

Change-Id: I821a78649ad6f07e4709fa343a0e678e4193a068

README.rst

@@ -275,7 +275,9 @@ If SSL needs to be enabled follow this step or skip to next step::
     For locally generating and testing, please refer to below link:
         http://tech.paulcz.net/2016/01/secure-docker-with-tls/
 
-Run Kuryr Server from command below::
+Run Kuryr Server with the command below. If you have uwsgi installed this
+command would run Kuryr under it. You can override this behaviour by
+setting `KURYR_USE_UWSGI=False`::
 
     $ sudo ./scripts/run_kuryr.sh
 

releasenotes/notes/use-uwsgi-to-run-server-4f43e615fd277c73.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    scripts/run_kuryr.sh now defaults to running api server under uwsgi. This behaviour
+    can be controlled by KURYR_USE_UWSGI env variable (default True).
+    In case it is set to False or uwsgi is abscent api would be run as usual.

scripts/run_kuryr.sh

@@ -76,4 +76,34 @@ if [[ ! -f "${KURYR_CONFIG}" ]]; then
     echo "Done"
 fi
 
-PYTHONPATH=${KURYR_HOME} python ${KURYR_HOME}/scripts/run_server.py  --config-file /etc/kuryr/kuryr.conf $@
+KURYR_USE_UWSGI=${KURYR_USE_UWSGI:-True}
+KURYR_UWSGI_PROCESSES=${KURYR_UWSGI_PROCESSES:-1}
+KURYR_UWSGI_THREADS=${KURYR_UWSGI_THREADS:-1}
+
+UWSGI_BIN=$(which uwsgi)
+if [[ -z "UWSGI_BIN" && $KURYR_USE_UWSGI == "True" ]]; then
+    echo "Requested uwsgi usage, but no uwsgi executable is available. Falling back to run_server.py"
+    echo "To suppress this message set KURYR_USE_UWSGI to False"
+    KURYR_USE_UWSGI="False"
+fi
+
+UWSGI_ADDITIONAL_ARGS=()
+if [[ $KURYR_USE_UWSGI == "True" ]]; then
+    if [[ "$VIRTUAL_ENV" ]]; then
+        UWSGI_ADDITIONAL_ARGS=( --virtualenv $VIRTUAL_ENV )
+    fi
+    echo "Starting uwsgi with ${KURYR_UWSGI_PROCESSES} processes and ${KURYR_UWSGI_THREADS} threads"
+    $UWSGI_BIN \
+        --plugins python \
+        --http-socket :23750 \
+        --wsgi kuryr_libnetwork.server:app \
+        --python-path "${KURYR_HOME}" \
+        --pyargv "--config-file ${KURYR_CONFIG}" \
+        --master \
+        --need-app \
+        --processes "$KURYR_UWSGI_PROCESSES" \
+        --threads "$KURYR_UWSGI_THREADS" \
+        "${UWSGI_ADDITIONAL_ARGS[@]}"
+else
+    PYTHONPATH="${KURYR_HOME}" python "${KURYR_HOME}/scripts/run_server.py"  --config-file "${KURYR_CONFIG}" "$@"
+fi