[FRR] Create a separate script to wait zebra to be ready to receive connections (sonic-net#6519)

The requirement for zebra to be ready to accept connections is a generic problem that is not 
specific to bgpd. Making the script to wait for zebra socket a separate script and let bgpd and 
staticd to wait for zebra socket.

Author: shi-su

dockers/docker-fpm-frr/Dockerfile.j2

@@ -54,9 +54,10 @@ COPY ["TSA", "/usr/bin/TSA"]
 COPY ["TSB", "/usr/bin/TSB"]
 COPY ["TSC", "/usr/bin/TSC"]
 COPY ["files/supervisor-proc-exit-listener", "/usr/bin"]
-COPY ["bgpd.sh", "/usr/bin/"]
+COPY ["zsocket.sh", "/usr/bin/"]
 RUN chmod a+x /usr/bin/TSA && \
     chmod a+x /usr/bin/TSB && \
-    chmod a+x /usr/bin/TSC
+    chmod a+x /usr/bin/TSC && \
+    chmod a+x /usr/bin/zsocket.sh
 
 ENTRYPOINT ["/usr/bin/docker_init.sh"]

dockers/docker-fpm-frr/frr/supervisord/supervisord.conf.j2

@@ -39,6 +39,17 @@ stderr_logfile=syslog
 dependent_startup=true
 dependent_startup_wait_for=rsyslogd:running
 
+[program:zsocket]
+command=/usr/bin/zsocket.sh
+priority=4
+autostart=false
+autorestart=false
+startsecs=0
+stdout_logfile=syslog
+stderr_logfile=syslog
+dependent_startup=true
+dependent_startup_wait_for=zebra:running
+
 [program:staticd]
 command=/usr/lib/frr/staticd -A 127.0.0.1
 priority=4
@@ -48,7 +59,7 @@ startsecs=0
 stdout_logfile=syslog
 stderr_logfile=syslog
 dependent_startup=true
-dependent_startup_wait_for=zebra:running
+dependent_startup_wait_for=zsocket:exited
 
 {% if DEVICE_METADATA.localhost.frr_mgmt_framework_config is defined and DEVICE_METADATA.localhost.frr_mgmt_framework_config == "true" %}
 [program:bfdd]
@@ -65,7 +76,7 @@ dependent_startup_wait_for=zebra:running
 {% endif %}
 
 [program:bgpd]
-command=/usr/bin/bgpd.sh -A 127.0.0.1 -M snmp
+command=/usr/lib/frr/bgpd -A 127.0.0.1 -M snmp
 priority=5
 stopsignal=KILL
 autostart=false
@@ -74,7 +85,7 @@ startsecs=0
 stdout_logfile=syslog
 stderr_logfile=syslog
 dependent_startup=true
-dependent_startup_wait_for=zebra:running
+dependent_startup_wait_for=zsocket:exited
 
 {% if DEVICE_METADATA.localhost.frr_mgmt_framework_config is defined and DEVICE_METADATA.localhost.frr_mgmt_framework_config == "true" %}
 [program:ospfd]

dockers/docker-fpm-frr/bgpd.sh dockers/docker-fpm-frr/zsocket.shdockers/docker-fpm-frr/bgpd.sh renamed to dockers/docker-fpm-frr/zsocket.sh

@@ -5,8 +5,8 @@ port=2601
 
 function help()
 {
-    echo "This script aims to ensure zebra is ready to accept connections before starting bgpd"
-    echo "Usage: $0 [options] [bgpd options]"
+    echo "This script aims to ensure zebra is ready to accept connections"
+    echo "Usage: $0 [options]"
     echo "Options:"
     echo " -a   Zebra address"
     echo " -o   Zebra port"
@@ -23,11 +23,14 @@ while getopts ":a:o:h" opt; do
             ;;
     esac
 done
-shift $((OPTIND-1))
 
+start=$(date +%s.%N)
 timeout 5s bash -c -- "until </dev/tcp/${addr}/${port}; do sleep 0.1;done"
 if [ "$?" != "0" ]; then
     logger -p error "Error: zebra is not ready to accept connections"
+else
+    timespan=$(awk "BEGIN {print $(date +%s.%N)-$start; exit}")
+    logger -p info "It took ${timespan} seconds to wait for zebra to be ready to accept connections"
 fi
 
-exec /usr/lib/frr/bgpd "$@"
+exit 0