OpenStack —— 虚拟机的启动过程简述(八)

micromax

　　

• 　　Dashboard or CLI gets the user credential and does the REST call to Keystone for authentication.
  
  
• 　　Keystone authenticate the credentials and generate & send back auth-token which will be used for sending request to other Components through REST-call.
  
• 　　Dashboard or CLI convert the new instance request specified in  ‘launch instance’ or ‘nova-boot’ form to REST API request and send it to nova-api.
  
• 　　nova-api receive the request and sends the request for validation auth-token and access permission to keystone.
  
• 　　Keystone validates the token and sends updated auth headers with roles and permissions.
  
• 　　nova-api interacts with nova-database.
  
• 　　Creates initial db entry for new instance.
  
• 　　 nova-api sends the rpc.call request to nova-scheduler excepting to get  updated instance entry with host ID specified.
  
• 　　nova-scheduler picks the request from the queue.
  
• 　　nova-scheduler interacts with nova-database to find an appropriate host via filtering and weighing.
  
• 　　Returns the updated instance entry with appropriate host ID after filtering and weighing.
  
• 　　nova-scheduler sends the rpc.cast request to nova-compute for ‘launching instance’ on appropriate host .
  
• 　　nova-compute picks the request from the queue.
  
• 　　nova-compute send the rpc.call request to nova-conductor to fetch the instance information such as host ID and flavor( Ram , CPU ,Disk).
  
• 　　nova-conductor picks the request from the queue.
  
• 　　nova-conductor interacts with nova-database.
  
• 　　Return the instance information.
  
• 　　nova-compute picks the instance information from the queue.
  
• 　　nova-compute does the REST call by passing auth-token to glance-api  to get the Image URI by Image ID from glance and upload image from image storage.
  
• 　　glance-api validates the auth-token with keystone.
  
• 　　nova-compute get the image metadata.
  
• 　　nova-compute does the REST-call by passing auth-token to Network API to allocate and configure the network such that instance gets the IP address.
  
• 　　quantum-server validates the auth-token with keystone.
  
• 　　nova-compute get the network info.
  
• 　　nova-compute does the REST call by passing auth-token to Volume API to attach volumes to instance.
  
• 　　cinder-api validates the auth-token withkeystone.
  
• 　　nova-compute gets the block storage info.
  
• 　　nova-compute generates data for hypervisor driver and executes request on Hypervisor( via libvirt or api).