Re: [libvirt] [PATCH 0/5] Support embedding the QEMU driver in client apps directly

This patch series proposes a new way to build a "libvirt QEMU shim" which supports more use cases than the previous approach from last year, as well as being vastly simpler to implement. Specifically - We can use this to embed the QEMU driver in unit tests allowing the full range of odriver functionality to be exercised during *unit* testing without interfering with the host OS libvirtd. - Apps like libguestfs can embed the QEMU driver to allow them to spawn VMs that are immediate children of their app, thus inheriting process context, as well as hiding these "service VM" from the main libvirtd. This would avoid a common irritation where libguestfs VMs suddenly appear & disappear in virt-manager's VM list. - Apps like kubevirt could use this to eliminate the need to use the RPC layer for libvirt. It can directly embed the QEMU driver giving it more direct control over how it is run & again inheriting process state. This is useful for kubevirt's one VM per container model where Kubernetes itself provides the aggregated view, thus making libvirtd's aggregated view redundant - The previous shim was very much one shim == one QEMU process. This new embed approach supports that of course, but there's also the option to run multiple VMs if desired. - Using a virtual root directory for QEMU driver state meams we do not need to solve the hard refactoring problem of getting the main libvirtd to detect the VMs launched via the shim. They can safely live independantly. - Thanks to the driver refactoring work it is still possible for the embedded drivers to talk to main libvirtd to use the secondary drivers for storage/network/etc if needed. Ideally we would allow those secondary drivers to be embedded too but that's not implemented here. Most important would be the secrets driver. Other drivers are much less important. Daniel P. Berrangé (5): access: report an error if no access manager is present libvirt: pass a root directory path into drivers qemu: honour the root parameter during driver initialization libvirt: support an "embed" URI path selector for QEMU driver qemu: introduce a new style libvirt_qemu_shim program src/access/viraccessmanager.c | 5 ++ src/driver-state.h | 1 + src/interface/interface_backend_netcf.c | 1 + src/interface/interface_backend_udev.c | 1 + src/libvirt.c | 41 ++++++++++++++- src/libvirt_internal.h | 1 + src/libxl/libxl_driver.c | 1 + src/lxc/lxc_driver.c | 2 + src/network/bridge_driver.c | 1 + src/node_device/node_device_hal.c | 1 + src/node_device/node_device_udev.c | 1 + src/nwfilter/nwfilter_driver.c | 1 + src/qemu/Makefile.inc.am | 7 +++ src/qemu/qemu_conf.c | 41 +++++++++------ src/qemu/qemu_conf.h | 3 +- src/qemu/qemu_driver.c | 9 ++-- src/qemu/qemu_shim.c | 70 +++++++++++++++++++++++++ src/remote/remote_daemon.c | 1 + src/remote/remote_driver.c | 8 +++ src/secret/secret_driver.c | 1 + src/storage/storage_driver.c | 1 + src/vz/vz_driver.c | 1 + 22 files changed, 179 insertions(+), 20 deletions(-) create mode 100644 src/qemu/qemu_shim.c