[files]: add topology service

* add script to configure virtual switch internal topology
* create service to manage topology
* install topology service in sonic_debian_extension

Signed-off-by: Lawrence Lee <t-lale@microsoft.com>

files/build_templates/sonic_debian_extension.j2

@@ -208,6 +208,13 @@ sudo cp $IMAGE_CONFIGS/hostname/hostname-config.service  $FILESYSTEM_ROOT/etc/sy
 echo "hostname-config.service" | sudo tee -a $GENERATED_SERVICE_FILE
 sudo cp $IMAGE_CONFIGS/hostname/hostname-config.sh $FILESYSTEM_ROOT/usr/bin/
 
+# Copy internal topology configuration scripts
+{%- if sonic_asic_platform == "vs" %}
+sudo cp $IMAGE_CONFIGS/topology/topology.service $FILESYSTEM_ROOT/etc/systemd/system/
+echo "topology.service" | sudo tee -a $GENERATED_SERVICE_FILE
+sudo cp $IMAGE_CONFIGS/topology/topology.sh $FILESYSTEM_ROOT/usr/bin
+{%- endif %}
+
 # Copy updategraph script and service file
 j2 files/build_templates/updategraph.service.j2 | sudo tee $FILESYSTEM_ROOT/etc/systemd/system/updategraph.service
 sudo cp $IMAGE_CONFIGS/updategraph/updategraph $FILESYSTEM_ROOT/usr/bin/

files/image_config/topology/topology.service

@@ -0,0 +1,17 @@
+[Unit]
+Description=Internal topology service
+Requires=namespace@0.service namespace@1.service namespace@2.service namespace@3.service namespace@4.service namespace@5.service
+After=namespace@0.service namespace@1.service namespace@2.service namespace@3.service namespace@4.service namespace@5.service 
+Before=database@0.service database@1.service database@2.service database@3.service database@4.service database@5.service
+PartOf=namespace@0.service namespace@1.service namespace@2.service namespace@3.service namespace@4.service namespace@5.service
+
+[Service]
+Type=oneshot
+User=root
+RemainAfterExit=yes
+ExecStart=/usr/bin/topology.sh start
+ExecStop=/usr/bin/topology.sh stop
+
+[Install]
+WantedBy=multi-user.target
+

files/image_config/topology/topology.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+
+start () {
+    # Move external links into assigned frontend namespaces
+    # eth0  - eth15: namespace2
+    # eth16 - eth31: namespace3
+    # eth32 - eth47: namespace4
+    # eth48 - eth63: namespace5
+    for NS in `seq 2 5`; do
+        for NUM in `seq 1 16`; do
+            ORIG="eth$((16 * $(($NS - 2)) + $NUM - 1))"
+            TEMP="ethTemp999"
+            NEW="eth$(($NUM + 16))"
+            ip link set dev $ORIG down
+            ip link set dev $ORIG name $TEMP # rename to prevent conflicts before renaming in new namespace
+            ip link set dev $TEMP netns namespace$NS
+            sudo ip netns exec namespace$NS ip link set $TEMP name $NEW # rename to final interface name
+            sudo ip netns exec namespace$NS ip link set $NEW up 
+        done
+    done
+
+    # Connect all backend namespaces to frontend namespaces
+    for BACKEND in `seq 0 1`; do
+        for FRONTEND in `seq 2 5`; do
+            for LINK in `seq 1 8`; do
+                BACK_NAME="eth$((8 * $(($FRONTEND - 2)) + $LINK))"
+                FRONT_NAME="eth$((8 * $BACKEND + $LINK))" 
+                TEMP_BACK="ethBack999"
+                TEMP_FRONT="ethFront999"
+
+                ip link add $TEMP_BACK type veth peer name $TEMP_FRONT # temporary name to prevent conflicts between interfaces
+                ip link set dev $TEMP_BACK netns namespace$BACKEND
+                ip link set dev $TEMP_FRONT netns namespace$FRONTEND 
+
+                sudo ip netns exec namespace$BACKEND ip link set $TEMP_BACK name $BACK_NAME
+                sudo ip netns exec namespace$FRONTEND ip link set $TEMP_FRONT name $FRONT_NAME
+
+                sudo ip netns exec namespace$BACKEND ip link set $BACK_NAME up
+                sudo ip netns exec namespace$FRONTEND ip link set $FRONT_NAME up
+            done
+        done
+    done
+}
+
+stop() {
+    for NS in `seq 2 5`; do
+        for NUM in `seq 1 16`; do
+            TEMP="eth999"
+            OLD="eth$(($NUM + 16))"
+            NAME="eth$((16 * $(( $NS - 2)) + $NUM - 1))"
+            sudo ip netns exec namespace$NS ip link set dev $OLD down
+            sudo ip netns exec namespace$NS ip link set dev $OLD name $TEMP
+            sudo ip netns exec namespace$NS ip link set dev $TEMP netns 1
+            ip link set dev $TEMP name $NAME
+            ip link set dev $NAME up
+        done
+    done
+
+    for NS in `seq 0 1`; do
+        for NUM in `seq 1 32`; do
+            sudo ip netns exec namespace$NS ip link set dev eth$NUM down
+            sudo ip netns exec namespace$NS ip link delete dev eth$NUM
+        done
+    done
+}
+
+case "$1" in
+    start|stop)
+        $1
+        ;;
+    *)
+        echo "Usage: $0 {start|stop}"
+        ;;
+esac
+