[ChassisDB]: bring up ChassisDB service (sonic-net#5283)

bring up chassisdb service on sonic switch according to the design in
Distributed Forwarding in VoQ Arch HLD

Signed-off-by: Honggang Xu <hxu@arista.com>

**- Why I did it**
To bring up new ChassisDB service in sonic as designed in ['Distributed forwarding in a VOQ architecture HLD' ](https://github.com/Azure/SONiC/blob/90c1289eaf89a70939e7c81e042e261947c6a850/doc/chassis/architecture.md). 

**- How I did it**
Implement the section 2.3.1 Global DB Organization of the VOQ architecture HLD.

**- How to verify it**
ChassisDB service won't start without chassisdb.conf file on the existing platforms.
ChassisDB service is accessible with global.conf file in the distributed arichitecture.

Signed-off-by: Honggang Xu <hxu@arista.com>

device/arista/x86_64-arista_7800_sup/chassisdb.conf

@@ -0,0 +1,2 @@
+start_chassis_db=1
+chassis_db_address=127.100.1.1

device/arista/x86_64-arista_7800r3_48cq2_lc/chassisdb.conf

@@ -0,0 +1 @@
+chassis_db_address=127.100.1.1

dockers/docker-database/Dockerfile.j2

@@ -45,5 +45,6 @@ COPY ["database_global.json.j2", "/usr/share/sonic/templates/"]
 COPY ["files/supervisor-proc-exit-listener", "/usr/bin"]
 COPY ["files/sysctl-net.conf", "/etc/sysctl.d/"]
 COPY ["critical_processes", "/etc/supervisor"]
+COPY ["files/update_chassisdb_config", "/usr/local/bin/"]
 
 ENTRYPOINT ["/usr/local/bin/docker-database-init.sh"]

dockers/docker-database/database_config.json.j2

@@ -5,6 +5,12 @@
             "port" : 6379,
             "unix_socket_path" : "/var/run/redis{{NAMESPACE_ID}}/redis.sock",
             "persistence_for_warm_boot" : "yes"
+        },
+        "redis_chassis":{
+            "hostname" : "redis_chassis.server",
+            "port": 6380,
+            "unix_socket_path": "/var/run/redis-chassis/redis_chassis.sock",
+            "persistence_for_warm_boot" : "yes"
         }
     },
     "DATABASES" : {
@@ -72,6 +78,11 @@
             "id" : 11,
             "separator": "|",
             "instance" : "redis"
+        },
+        "CHASSIS_APP_DB" : {
+            "id" : 12,
+            "separator": "|",
+            "instance" : "redis_chassis"
         }
     },
     "VERSION" : "1.0"

dockers/docker-database/docker-database-init.sh

@@ -19,14 +19,45 @@ fi
 
 REDIS_DIR=/var/run/redis$NAMESPACE_ID
 mkdir -p $REDIS_DIR/sonic-db
+mkdir -p /etc/supervisor/conf.d/
 
 if [ -f /etc/sonic/database_config$NAMESPACE_ID.json ]; then
     cp /etc/sonic/database_config$NAMESPACE_ID.json $REDIS_DIR/sonic-db/database_config.json
 else
     HOST_IP=$host_ip j2 /usr/share/sonic/templates/database_config.json.j2 > $REDIS_DIR/sonic-db/database_config.json
 fi
 
-mkdir -p /etc/supervisor/conf.d/
+# on VoQ system, we only publish redis_chassis instance and CHASSIS_APP_DB when
+# either chassisdb.conf indicates starts chassis_db or connect to chassis_db,
+# and redis_chassis instance is started in different container.
+# in order to do that, first we save original database config file, then
+# call update_chasissdb_config to remove chassis_db config from
+# the original database config file and use the modified config file to generate
+# supervisord config, so that we won't start redis_chassis service.
+# then we will decide to publish modified or original database config file based
+# on the setting in chassisdb.conf
+start_chassis_db=0
+chassis_db_address=""
+chassis_db_port=""
+chassisdb_config="/etc/sonic/chassisdb.conf"
+[ -f $chassisdb_config ] && source $chassisdb_config
+
+db_cfg_file="/var/run/redis/sonic-db/database_config.json"
+db_cfg_file_tmp="/var/run/redis/sonic-db/database_config.json.tmp"
+cp $db_cfg_file $db_cfg_file_tmp
+
+if [[ $DATABASE_TYPE == "chassisdb" ]]; then
+    # Docker init for database-chassis
+    echo "Init docker-database-chassis..."
+    update_chassisdb_config -j $db_cfg_file_tmp -k -p $chassis_db_port
+    mkdir -p /var/run/redis/sonic-db
+    cp /etc/default/sonic-db/database_config.json /var/run/redis/sonic-db
+    # generate all redis server supervisord configuration file
+    sonic-cfggen -j $db_cfg_file_tmp -t /usr/share/sonic/templates/supervisord.conf.j2 > /etc/supervisor/conf.d/supervisord.conf
+    rm $db_cfg_file_tmp
+    exec /usr/bin/supervisord
+    exit 0
+fi
 
 # copy/generate the database_global.json file if this is global database service in multi asic platform.
 if [[ $NAMESPACE_ID == "" ]] && [[ $NAMESPACE_COUNT -gt 1 ]]
@@ -37,8 +68,15 @@ then
         j2 /usr/share/sonic/templates/database_global.json.j2 > $REDIS_DIR/sonic-db/database_global.json
     fi
 fi
+# delete chassisdb config to generate supervisord config
+update_chassisdb_config -j $db_cfg_file_tmp -d
+sonic-cfggen -j $db_cfg_file_tmp -t /usr/share/sonic/templates/supervisord.conf.j2 > /etc/supervisor/conf.d/supervisord.conf
 
-# generate all redis server supervisord configuration file
-sonic-cfggen -j /var/run/redis/sonic-db/database_config.json -t /usr/share/sonic/templates/supervisord.conf.j2 > /etc/supervisor/conf.d/supervisord.conf
+if [[ "$start_chassis_db" != "1" ]] && [[ -z "$chassis_db_address" ]]; then
+     cp $db_cfg_file_tmp $db_cfg_file
+else
+     update_chassisdb_config -j $db_cfg_file -p $chassis_db_port
+fi
+rm $db_cfg_file_tmp
 
 exec /usr/bin/supervisord

dockers/docker-database/supervisord.conf.j2

@@ -20,7 +20,7 @@ stderr_logfile=syslog
 {% if INSTANCES %}
 {%     for redis_inst, redis_items in INSTANCES.iteritems() %}
 [program: {{ redis_inst }}]
-{% if redis_items['hostname'] != '127.0.0.1' %}
+{% if redis_items['hostname'] != '127.0.0.1' and redis_inst != 'redis_chassis' %}
 {%- set LOOPBACK_IP = '127.0.0.1' -%}
 {%- else -%}
 {%- set LOOPBACK_IP = '' -%}

files/build_templates/config-chassisdb.service.j2

@@ -0,0 +1,12 @@
+[Unit]
+Description=Config chassis_db
+After=rc-local.service
+Requires=rc-local.service
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/config-chassisdb
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target