[router-advertiser] Add templated script to wait for pertinent interfaces to be ready before starting radvd (sonic-net#2558)

Author: yxieca

dockers/docker-router-advertiser/Dockerfile.j2

@@ -30,6 +30,6 @@ RUN rm -rf /debs
 
 COPY ["start.sh", "/usr/bin/"]
 COPY ["docker-router-advertiser.supervisord.conf", "/etc/supervisor/conf.d/"]
-COPY ["radvd.conf.j2", "/usr/share/sonic/templates/"]
+COPY ["radvd.conf.j2", "wait_for_intf.sh.j2", "/usr/share/sonic/templates/"]
 
 ENTRYPOINT ["/usr/bin/supervisord"]

dockers/docker-router-advertiser/start.sh

@@ -21,5 +21,12 @@ if [ $NUM_IFACES -eq 0 ]; then
     exit 0
 fi
 
+# Generate the script that waits for pertinent interfaces to come up and make it executable
+sonic-cfggen -d -t /usr/share/sonic/templates/wait_for_intf.sh.j2 > /usr/bin/wait_for_intf.sh
+chmod +x /usr/bin/wait_for_intf.sh
+
+# Wait for pertinent interfaces to come up
+/usr/bin/wait_for_intf.sh
+
 # Start the router advertiser
 supervisorctl start radvd

dockers/docker-router-advertiser/wait_for_intf.sh.j2

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+STATE_DB_IDX="6"
+
+VLAN_TABLE_PREFIX="VLAN_TABLE"
+
+function wait_until_iface_ready
+{
+    TABLE_PREFIX=$1
+    IFACE=$2
+
+    echo "Waiting until interface $IFACE is ready..."
+
+    # Wait for the interface to come up
+    # (i.e., interface is present in STATE_DB and state is "ok")
+    while true; do
+        RESULT=$(redis-cli -n ${STATE_DB_IDX} HGET "${TABLE_PREFIX}|${IFACE}" "state" 2> /dev/null)
+        if [ x"$RESULT" == x"ok" ]; then
+            break
+        fi
+
+        sleep 1
+    done
+
+    echo "Interface ${IFACE} is ready!"
+}
+
+
+# Wait for all interfaces to be up and ready
+{% for (name, prefix) in VLAN_INTERFACE %}
+wait_until_iface_ready ${VLAN_TABLE_PREFIX} {{ name }}
+{% endfor %}

rules/docker-router-advertiser.mk

@@ -2,6 +2,7 @@
 
 DOCKER_ROUTER_ADVERTISER = docker-router-advertiser.gz
 $(DOCKER_ROUTER_ADVERTISER)_PATH = $(DOCKERS_PATH)/docker-router-advertiser
+$(DOCKER_ROUTER_ADVERTISER)_DEPENDS += $(REDIS_TOOLS)
 $(DOCKER_ROUTER_ADVERTISER)_LOAD_DOCKERS = $(DOCKER_CONFIG_ENGINE)
 SONIC_DOCKER_IMAGES += $(DOCKER_ROUTER_ADVERTISER)
 SONIC_INSTALL_DOCKER_IMAGES += $(DOCKER_ROUTER_ADVERTISER)