add support for save-on-set to gnmi

sonic-net/SONiC#1297

Author: rlucus

dockers/docker-sonic-gnmi/gnmi-native.sh

@@ -102,4 +102,14 @@ else
     fi
 fi
 
+# gNMI save-on-set behavior is disabled by default.
+# Save-on-set can be turned on by setting the "TELEMETRY|gnmi|save_on_set"
+# to "true".
+readonly SAVE_ON_SET=$(echo ${GNMI} | jq -r '.save_on_set // empty')
+if [ ! -z "${SAVE_ON_SET}" ]; then
+    TELEMETRY_ARGS+=" --with-save-on-set=${SAVE_ON_SET}"
+else
+    TELEMETRY_ARGS+=" --with-save-on-set=false"
+fi
+
 exec /usr/sbin/telemetry ${TELEMETRY_ARGS}