OpenStack —— 虚拟机的启动过程简述(八)

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 with keystone.

nova-compute gets the block storage info.

nova-compute generates data for hypervisor driver and executes request on Hypervisor( via libvirt or api).