07. Nova → 1.nova computing architecture → 3. From the virtual machine creation process to see how nova- * sub-services work together

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1. Customer (end-user can be OpenStack, may also be other programs) sends a request to the API (nova-api): "Help me create a virtual machine"
2. API request to do some necessary treatment, sent a message to the Messaging (RabbitMQ): "Let Scheduler to create a virtual machine"
3. Scheduler (nova-scheduler) obtained from Messaging API message sent to it, and then performing a scheduling algorithm, node A is selected from a plurality of computing nodes
4. Scheduler sends a message to the Messaging: "Creating the virtual machines on computing node A"
5. Computing node A Compute (nova-compute) obtained from the Messaging Scheduler message sent to it, and then starts the virtual machine on the local node Hypervisor.
6. In the process of the virtual machine created, Compute If you need to query or update the database information, will be the Conductor (nova-conductor) to send a message, Conductor is responsible for database access via Messaging.