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).
本文出自 “运维点滴记录” 博客，请务必保留此出处http://wzlinux.blog.51cto.com/8021085/1964195