[services] Ensure swss and syncd services start before dependent services (sonic-net#2634)

* [services] Ensure swss and syncd services start before dependent services

* Add 'attach' functions to scripts which get installed to /usr/local/bin so that services only reference the one script each

* Add 'After=swss.service' to syncd.service

Author: jleveque

files/build_templates/swss.service.j2

@@ -13,7 +13,8 @@ Before=ntp-config.service
 [Service]
 User=root
 Environment=sonic_asic_platform={{ sonic_asic_platform }}
-ExecStart=/usr/local/bin/swss.sh start
+ExecStartPre=/usr/local/bin/swss.sh start
+ExecStart=/usr/local/bin/swss.sh attach
 ExecStop=/usr/local/bin/swss.sh stop
 
 [Install]

files/build_templates/syncd.service.j2

@@ -13,12 +13,14 @@ After=opennsl-modules-4.9.0-8-amd64.service
 {% elif sonic_asic_platform == 'nephos' %}
 After=nps-modules-4.9.0-8-amd64.service
 {% endif %}
+After=swss.service
 Before=ntp-config.service
 
 [Service]
 User=root
 Environment=sonic_asic_platform={{ sonic_asic_platform }}
-ExecStart=/usr/local/bin/syncd.sh start
+ExecStartPre=/usr/local/bin/syncd.sh start
+ExecStart=/usr/local/bin/syncd.sh attach
 ExecStop=/usr/local/bin/syncd.sh stop
 
 [Install]

files/scripts/swss.sh

@@ -109,6 +109,9 @@ start() {
     if [[ x"$WARM_BOOT" != x"true" ]]; then
         /bin/systemctl start ${PEER}
     fi
+}
+
+attach() {
     /usr/bin/${SERVICE}.sh attach
 }
 
@@ -134,11 +137,11 @@ stop() {
 }
 
 case "$1" in
-    start|stop)
+    start|attach|stop)
         $1
         ;;
     *)
-        echo "Usage: $0 {start|stop}"
+        echo "Usage: $0 {start|attach|stop}"
         exit 1
         ;;
 esac

files/scripts/syncd.sh

@@ -117,6 +117,9 @@ start() {
     debug "Started ${SERVICE} service..."
 
     unlock_service_state_change
+}
+
+attach() {
     /usr/bin/${SERVICE}.sh attach
 }
 
@@ -165,11 +168,11 @@ stop() {
 }
 
 case "$1" in
-    start|stop)
+    start|attach|stop)
         $1
         ;;
     *)
-        echo "Usage: $0 {start|stop}"
+        echo "Usage: $0 {start|attach|stop}"
         exit 1
         ;;
 esac