Virtual Machines Automation from Hypervisors using Qemu-Agent on KVM

##### ISSUE TYPE
* Feature Idea

##### COMPONENT NAME
Categorize the issue, API, KVM, HYP, UI

##### CLOUDSTACK VERSION
Coming versions

##### SUMMARY
Many of us are using Cloudstack to provide public and private cloud services for our internal teams and clients, so normally we don't handle passwords or ssh key password to access the vm's operating system to orchestrate applications lifecycle. So my proposal is that just like user-data works for the first boot we can register actions or commands that we can apply to client's vm using qemu-agent capabilities in KVM so we leverage services like:

- DBaaS
- Managed Applications
- Improvements on CSK

##### STEPS TO REPRODUCE

Cloudstack access the hyp where the vm resides and applies commands like:

virsh qemu-agent-command "$VM_NAME" "$COMMAND_JSON"

Comece mapeando como o CloudStack chega aos hipervisores KVM e onde as ações de API, UI e hipervisor são definidas. Leia o exemplo de qemu-agent-command e esclareça o ciclo de vida compatível dos comandos, as permissões e o tratamento de falhas. O trabalho concluído deve incluir um escopo de funcionalidade acordado e um caminho de implementação para aplicar ações do QEMU-agent às máquinas virtuais convidadas.

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