In our previous blog posts we mostly focused on virtual machine live migration performance comparing pre-copy, post-copy and hybrid approaches in an Openstack context rather than exploring other live migration features. Libvirt together with the Qemu hypervisor provides many migration configuration options. One of these options is a possibility to use tunneled live migration. Recently we found that the current libvirt tunneling implementation is not supported in post-copy migration. Consequently, In order to make the post-copy patch more production ready we decided to support the community and add support for post-copy tunneled live migration to libvirt on our own. This blog post describes the whole story of immersing ourselves into the open source community and hacking an established open source project since we believe this experience can be generalized. Continue reading