The working flow of running an instance in NOVA

Working Flow

1. User send running instance request to API server



2. API Server drop job into queue pool .

3. Networker prepare IP for instance

4. Scheduler decides which compute node will be use for running instance.

5. That compute node receives the command from pool and then cache image from image store.

6. To spawn the image on compute node

7. Once instance boot up , it will try to get network info. the info send to instance from network depends on different network mode.

Flat                          Inject network parameter 
Flat DHCP               DHCP request from NOVA-network dnsmasq service 
Vlan with DHCP       request from NOVA-network dnsmasq service 

8. Compute node add iptable rule for routing instance to nova-network host

=====Terminate=====

9. User send request to API server

10. Compute node will terminate instance

11. Clean the rule of instance

12. Nova-network return IP to the pool (database)

13. update database