HLD: Azure/SONiC#646
Introducing chassisd process to monitor status of the control, line and fabric cards in a modular chassis.
- Why I did it
Modular Chassis has control-cards, line-cards and fabric-cards along with other peripherals. Chassisd will be a central entity that has visibility of the entire chassis.
- How I did it
Chassisd process will monitor cards in the main thread. Another configuation_handling_task is created to listen to CONFIG_DB for admin_status up/down events. The monitored status is persisted in REDIS-DB.
