[libvirt] [PATCH 0/6] Enable fd passing / socket activation with LXC guest

[Daniel P. Berrange]

From: "Daniel P. Berrange" <berrange at redhat.com>

Systemd has a concept of socket activation whereby systemd
will listen on a TCP socket in the host. When a client arrives
on the socket, systemd will run a service, passing it the
pre-opened TCP server socket. The service can then accept the
client connection.

This patch series adds the ability to pass pre-opened file
descriptors into LXC guests. The file descriptors will be
made available to the 'init' process in the container,
starting from STDERR_FILENO + 1.

For example, assuming you have pre-opened a file descriptors
in your shell

 # exec 10>/tmp/foo
 # exec 20>/tmp/bar
 # exec 30>/tmp/wizz

You can then start a container with:

 # virsh -c lxc:/// start --pass-fds 10,20,30  demo

Inside that container the FDs will appear as 3, 4, 5:

 # virsh -c lxc:/// console demo
 Connected to domain demo
 Escape character is ^]
 sh-4.2# lsof -p 1 | grep /tmp
 sh        1 root    3w   REG   0,32        0 90226444 /tmp/foo
 sh        1 root    4w   REG   0,32        0 90238163 /tmp/bar
 sh        1 root    5w   REG   0,32        0 90238164 /tmp/wizz

Finally, if you run systemd inside the container, it can then
use these pre-opened file descriptors, passing them along when
launching services inside the container. So you have end-to-end
socket activation between the host & guest systemd instances.

Daniel P. Berrange (6):
  Introduce new domain create APIs to pass pre-opened FDs to LXC
  Introduce remote protocol support for virDomainCreate{XML}WithFiles
  Fix impl of virDomainCreateWithFlags remote client helper
  LXC: Wire up the virDomainCreate{XML}WithFiles methods
  Enable FD passing when starting guests with virsh
  Merge virCommandPreserveFD / virCommandTransferFD

 daemon/remote.c                       | 104 ++++++++++++++++++++++
 include/libvirt/libvirt.h.in          |  10 +++
 python/generator.py                   |   3 +
 python/libvirt-override-virConnect.py |  30 +++++++
 python/libvirt-override-virDomain.py  |  38 ++++++++
 python/libvirt-override.c             |  89 +++++++++++++++++++
 src/driver.h                          |  13 +++
 src/fdstream.c                        |   3 +-
 src/libvirt.c                         | 154 ++++++++++++++++++++++++++++++++
 src/libvirt_private.syms              |   3 +-
 src/libvirt_public.syms               |   6 ++
 src/lxc/lxc_container.c               | 136 ++++++++++++++++++++++-------
 src/lxc/lxc_container.h               |   6 +-
 src/lxc/lxc_controller.c              |  36 +++++++-
 src/lxc/lxc_driver.c                  |  45 ++++++++--
 src/lxc/lxc_process.c                 |  20 ++++-
 src/lxc/lxc_process.h                 |   1 +
 src/qemu/qemu_command.c               |  16 ++--
 src/remote/remote_driver.c            |  91 +++++++++++++++----
 src/remote/remote_protocol.x          |  32 ++++++-
 src/remote_protocol-structs           |  16 ++++
 src/uml/uml_conf.c                    |   3 +-
 src/util/vircommand.c                 | 159 ++++++++++++++++------------------
 src/util/vircommand.h                 |  13 +--
 tests/commandtest.c                   |   5 +-
 tools/virsh-domain.c                  |  82 +++++++++++++++++-
 tools/virsh.pod                       |  13 ++-
 27 files changed, 960 insertions(+), 167 deletions(-)

-- 
1.8.1.4