Hello, Devs. I would like to introduce a feature and decided to consult with you about its design before implementation. The feature is connected with KVM CloudStack agent. We have found it beneficial to be able to launch custom scripts upon VM start/stop. It can be done using Qemu hook but it has several drawbacks: - the hook is deployed by CS and adding additional lines into it leads to extra efforts when ACS package is updated. - it leads to deadlocks as you cannot effectively and easy to communicate with libvirt from hook even with "fork & exec" because security_groups.py and agent also participate and as a result it causes deadlocks.
Now, in the code, we have a call for "security_groups.py": Start: https://github.com/apache/cloudstack/blob/65f31f1a9fbc1c20cd752d80a7e1117efc0248a5/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/wrapper/LibvirtStartCommandWrapper.java#L103 Stop: https://github.com/apache/cloudstack/blob/65f31f1a9fbc1c20cd752d80a7e1117efc0248a5/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/wrapper/LibvirtStopCommandWrapper.java#L88 I would like is to introduce a more generic approach, so the administrator can specify additional scripts in the agent.properties, which will be called the same way "security_groups.py" called. custom.vm.start=/path/to/script1,path/to.script2 custom.vm.stop=/path/to/script3,path/to.script4 So, this feature will help users to do custom hotplug mechanisms. E.g. we have such implementation which adds per-account VXLAN as a hotplug ethernet device. So, even for a Basic Zone, every VM gets automatic second NIC which helps to build a private network for an account. Currently, we do the job thru adding lines into security_groups.py, which is not a good approach, especially for end users who don't want to hack the system. Also, I'm thinking about changing /etc/libvirt/hooks/qemu the same way, so it was just an entry point to /etc/libvirt/hooks/qemu.d/* located scripts. Let me know about this feature proposal and if its design is good, we start developing it. Have a good day. -- With best regards, Ivan Kudryavtsev Bitworks LLC Cell RU: +7-923-414-1515 Cell USA: +1-201-257-1512 WWW: http://bitworks.software/ <http://bw-sw.com/>
