The libvirtd daemon provides the traditional libvirt experience where
all the drivers are in a single daemon, and is accessible over both
local UNIX sockets and remote IP sockets.
In the new world we're having a set of per-driver daemons which will
primarily be accessed locally via their own UNIX sockets.
We still, however, need to allow for case of applications which will
connect to libvirt remotely. These remote connections can be done as
TCP/TLS sockets, or by SSH tunnelling to the UNIX socket.
In the later case, the old libvirt.so clients will only know about
the path to the old libvirtd socket /var/run/libvirt/libvirt-sock,
and not the new driver sockets /var/run/libvirt/virtqemud-sock.
It is also not desirable to expose the main driver specific daemons
over IP directly to minimize their attack service.
Thus the virtproxyd daemon steps into place, to provide TCP/TLS sockets,
and back compat for the old libvirtd UNIX socket path(s). It will then
forward all RPC calls made to the appropriate driver specific daemon.
Essentially it is equivalent to the old libvirtd with absolutely no
drivers registered except for the remote driver (and other stateless
drivers in libvirt.so).
We could have modified libvirtd so none of the drivers are registed
to get the same end result. We could even add a libvirtd.conf parameter
to control whether the drivers are loaded to enable users to switch back
to the old world if we discover bugs in the split-daemon model. Using a
new daemon though has some advantages
- We can make virtproxyd and the virtXXXd per-driver daemons all
have "Conflicts: libvirtd.service" in their systemd unit files.
This will guarantee that libvirtd is never started at the same
time, as this would result in two daemons running the same driver.
Fortunately drivers use locking to protect themselves, but it is
better to avoid starting a daemon we know will conflict.
- It allows us to break CLI compat to remove the --listen parameter.
Both listen_tcp and listen_tls parameters in /etc/libvirtd/virtd.conf
will default to zero. Either TLS or TCP can be enabled exclusively
though virtd.conf without requiring the extra step of adding --listen.
- It allows us to set a strict SELinux policy over virtproxyd. For
back compat the libvirtd policy must continue to allow all drivers
to run. We can't easily give a second policy to libvirtd which
locks it down. By introducing a new virtproxyd we can set a strict
policy for that daemon only.
- It gets rid of the weird naming of having a daemon with "lib" in
its name. Now all normal daemons libvirt ships will have "virt"
as their prefix not "libvirt".
- Distros can more easily choose their upgrade path. They can
ship both sets of daemons in their packages, and choose to
either enable libvirtd, or enable the per-driver daemons and
virtproxyd out of the box. Users can easily override this if
desired by just tweaking which systemd units are active.
After some time we can deprecate use of libvirtd and after some more
time delete it entirely, leaving us in a pretty world filled with
prancing unicorns.
The main downside with introducing a new daemon, and with the
per-driver daemons in general, is figuring out the correct upgrade
path.
The conservative option is to leave libvirtd running if it was
an existing installation. Only use the new daemons & virtproxyd
on completely new installs.
The aggressive option is to disable libvirtd if already running
and activate all the new daemons.
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Christophe de Dinechin <dinechin@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Prepare for reusing libvirtd source to create other daemons by making
the use of IP sockets conditionally defined by the make rules.
The main libvirtd daemon will retain IP listen ability, but all the
driver specific daemons will be local UNIX sockets only. Apps needing
IP connectivity will connect via the libvirtd daemon which will proxy
to the driver specfic daemon.
Reviewed-by: Christophe de Dinechin <dinechin@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Prepare for reusing libvirtd source to create other daemons by making
the daemon name conditionally defined by the make rules.
Reviewed-by: Christophe de Dinechin <dinechin@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Libvirtd has long had integration with avahi for advertising libvirtd
using mDNS when TCP/TLS listening is enabled. For a long time the
virt-manager application had support for auto-detecting libvirtds
on the local network using mDNS, but this was removed last year
commit fc8f8d5d7e3ba80a0771df19cf20e84a05ed2422
Author: Cole Robinson <crobinso@redhat.com>
Date: Sat Oct 6 20:55:31 2018 -0400
connect: Drop avahi support
Libvirtd can advertise itself over avahi. The feature is disabled by
default though and in practice I hear of no one actually using it
and frankly I don't think it's all that useful
The 'Open Connection' wizard has a disproportionate amount of code
devoted to this feature, but I don't think it's useful or worth
maintaining, so let's drop it
I've never heard of any other applications having support for using
mDNS to detect libvirtd instances. Though it is theoretically possible
something exists out there, it is clearly going to be a niche use case
in the virt ecosystem as a whole.
By removing avahi integration we can cut down the dependency chain for
the basic libvirtd install and reduce our code maint burden.
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This reverts commit a5e1602090.
Getting rid of unistd.h from our headers will require more work than
just fixing the broken mingw build. Revert it until I have a more
complete proposal.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
util/virutil.h bogously included unistd.h. Drop it and replace it by
including it directly where needed.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
In many files there are header comments that contain an Author:
statement, supposedly reflecting who originally wrote the code.
In a large collaborative project like libvirt, any non-trivial
file will have been modified by a large number of different
contributors. IOW, the Author: comments are quickly out of date,
omitting people who have made significant contribitions.
In some places Author: lines have been added despite the person
merely being responsible for creating the file by moving existing
code out of another file. IOW, the Author: lines give an incorrect
record of authorship.
With this all in mind, the comments are useless as a means to identify
who to talk to about code in a particular file. Contributors will always
be better off using 'git log' and 'git blame' if they need to find the
author of a particular bit of code.
This commit thus deletes all Author: comments from the source and adds
a rule to prevent them reappearing.
The Copyright headers are similarly misleading and inaccurate, however,
we cannot delete these as they have legal meaning, despite being largely
inaccurate. In addition only the copyright holder is permitted to change
their respective copyright statement.
Reviewed-by: Erik Skultety <eskultet@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Hypervisor drivers (e.g. QEMU) assume that they run in a separate
thread from the main event loop thread otherwise deadlocks can
occur. Therefore let's report an error if max_workers < 1 is set in
the libvirtd configuration file.
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Reviewed-by: Bjoern Walk <bwalk@linux.ibm.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
Having a daemon/ directory makes little sense from a code structure
point of view, as 90% of the code that is built into libvirtd already
lives in the src/ directory. The virtlockd and virlogd daemons also live
entirely in src/{locking,logging} directories. This moves the source
code for libvirtd into src/remote/, alongside the client code.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
