The document describes the main components of the Nova cloud computing management system in OpenStack. It discusses the roles of the nova-api, nova-conductor, nova-scheduler, and nova-compute services. The nova-api service handles user compute API calls. The nova-conductor acts as a database proxy. The nova-scheduler determines which compute node to place new instances on. The nova-compute service creates and terminates VM instances through hypervisor drivers.

1. Nova
components

2. Installations
# yum install nova-api nova-cert nova-conductor nova-consoleauth nova-novncproxy
nova-scheduler python-novaclient
# yum install nova-compute
On Controller Node
On Compute Node

3. Components
nova-novncproxy
nova-cert
nova-consoleauth
nova-network
nova-api-metadata
nova-api nova-conductor
nova-scheduler nova-computequeue
database

4. Components
nova-novncproxy
nova-cert
nova-consoleauth
nova-network
nova-api-metadata
nova-api nova-conductor
nova-scheduler nova-computequeue
database

5. Components
nova-novncproxy
nova-cert
nova-consoleauth
nova-network
nova-api-metadata
Neutron
nova-api nova-conductor
nova-scheduler nova-computequeue
database

6. Components
nova-novncproxy
nova-cert
nova-consoleauth
nova-api nova-conductor
nova-scheduler nova-computequeue
database

7. Components
nova-api nova-conductor
nova-scheduler nova-computequeue
database

8. Nova and External Services

9. Components > nova-api
nova-api nova-conductor
nova-scheduler nova-computequeue
database
HTTP Web Service!
Accepts & Responds to User’s Compute API calls
Supports OpenStack Compute API, Amazon EC2
API, Admin API.
Initiates Orchestration Activities.
POST /v2/{tenant_id}/servers/{server_id}/action

10. Components > nova-api
POST /v2/{tenant_id}/servers
Request Body
{
"server": {
"name": "server-test-1",
"imageRef": "b5660a6e-4b46-4be3-9707-6b47221b454f",
"flavorRef": "2",
"max_count": 1,
"min_count": 1,
"networks": [
{
"uuid": "d32019d3-bc6e-4319-9c1d-6722fc136a22"
}
],
"security_groups": [
{
"name": "default"
},
{
"name": "another-secgroup-name"
}
]
}
}
202 Accepted
Response Body
{

11. Components > nova-conductor
nova-api nova-conductor
nova-scheduler nova-computequeue
database
Database Proxy!
Acting as an intermediary between the compute
node and the database node and the database.

12. Components > nova-conductor
Why?
Auditing database operations, revoking access privileges.
That’s Difficult!
They host tenant instances.
Compute nodes are the least trusted of the services in OpenStack.

13. Components > nova-conductor
They strongly recommends
Be isolated to a management network,
Use SSL,
Create unique user accounts per service endpoint.

14. Restrict services to executing with parameters, …
Prevent directly accessing or modifying.
Unfortunately, it complicates fine-grained access control
and audit data access.
Because, it Focus on improving Security, effectively modifying.
Components > nova-conductor
-> Compute nodes are the least trusted
of the services in OpenStack. Because they host tenant instances.
-> Do not deploy it on Compute Nodes.

15. Components > nova-conductor
nova-api nova-conductor
nova-scheduler nova-computequeue
database
push
pop
push
pop

16. Components > nova-scheduler
nova-api nova-conductor
nova-scheduler nova-computequeue
database
Scheduler!
Takes VM requests from the queue.
Determine on which compute node host it.

17. Components > nova-scheduler
nova-api nova-conductor
nova-scheduler queue
mysql
nova-compute1
nova-compute2
nova-compute3
NEW Instance
Instance B
takes
determines
Create Instance

18. nova-scheduler
 Takes a VM instance and determine where it should run
(on which host).
 2 step process

19. nova-scheduler
• FilterScheduler is a default scheduler
– Supports filtering and weighting

20. • Filtering
– RetryFilter
• Prevents the scheduler from selecting the host that fails
to respond.
– AvailablilityZoneFilter
• Filters hosts by availability zone.
– RamFilter
• Select hosts that have sufficient RAM.
• Can overcommitment by configuration.
– ComputeFilter
• Passes all hosts that are operational and enabled.
nova-scheduler > filter scheduler

21. – ComputeCapabilitiesFilter
• Satisfy the extra specs associated with the instance type.
– ImagePropertiesFilter
• Filters hosts based on properties defined on the
instance's image.
nova-scheduler > filter scheduler

22. RAM-Filter

23. Availability Zone-Filter

24. Compute-Filter

25. Weighing
●Scheduler applies cost functions on each host and
calculates the weight.
●The least weighted host wins.

26. • Weighing
– Each time the scheduler selects a host and
subsequent selections are adjusted accordingly.
– Virtually consumes resources.
nova-scheduler > filter scheduler

27. In the end...
●The scheduler manager sends an rpc call to the
compute manager of selected hosts.
●The compute manager receives it from the queue and
runs its create_instance method and we get a running
VM instance.

28. Components > nova-compute
nova-api nova-conductor
nova-scheduler nova-computequeue
database
Worker Daemon!
Creates and terminates VMs through hypervisor APIs,
such as Xen, QEMU, KVM, Vmware, ….

29. It Supports multiple hypervisors.
Because, it Has an abstraction layer, Driver.
Components > nova-compute
nova-compute
Compute Agent
(KVM)
libvirt
KVM
VM VM
nova-compute
Compute Agent
(Hyper-v)
Hyper-v
VM VM
nova-scheduler
nova-compute
Abstraction layer,
Driver
any hypervisor
VM VM

30. Components > nova-compute
nova-api nova-conductor
nova-scheduler
nova-compute
queue
database
hypervisor
VM
VM launch

31. Hypervisor Types
• Type-1: bare metal hypervisor
• Type-2: hosted hypervisor
nova-compute > hypervisors

32. • Ironic
– OpenStack Component for managing and
provisioning Bare Metal servers.
– Not VMs.
– Makes physical servers as easy to provision as
VMs in cloud.
nova-compute > hypervisors

33. Components > nova-compute
keystone
Glance
Neutron
Cinder
Horizon or CLI
4
5
3
1
2
In more detail…
Provisioning Instance