libvirtd

Linux Virtualization Management Daemon

LIBVIRTD(8)

System Manager's Manual

libvirtd(8)

CONFIGURATION

The daemon can be configured using the configuration file. The default configuration file is:

$XDG_CONFIG_HOME/libvirt/libvirtd.conf

XDG Base Directory Specification

libvirtd follows the XDG Base Directory Specification, a standard that defines where applications should store configuration, runtime, and data files. This ensures consistent behavior across Linux distributions and desktop environments.

XDG_CONFIG_HOME

$XDG_CONFIG_HOME specifies the base directory for user-specific configuration files. If not set, it defaults to $HOME/.config.

What this means for libvirtd:

Your personal libvirt configuration lives in $HOME/.config/libvirt/
This keeps your VM settings separate from system-wide configs
Allows per-user customization without affecting other users
Makes it easy to backup and sync your VM configurations

XDG_RUNTIME_DIR

$XDG_RUNTIME_DIR is a directory for user-specific runtime files like sockets, PID files, and temporary data. It's typically /run/user/<uid> and is cleaned up when you log out.

What this means for libvirtd:

Unix domain sockets are created in /run/user/<uid>/libvirt/
These sockets enable communication between libvirt tools and the daemon
PID files track the daemon process for system management
Runtime files are automatically cleaned up when you log out

Configuration File Example

Here's a basic /etc/libvirt/libvirt.conf configuration file with explanations:

#
# libvirt.conf - Main libvirt configuration file
# This file controls how libvirt tools connect to hypervisors
#

# URI Aliases - Create shortcuts for frequently used connections
# These let you use 'virsh -c hail' instead of typing the full URI
uri_aliases = [
  "hail=qemu+ssh://[email protected]/system",
  "sleet=qemu+ssh://[email protected]/system",
  "local=qemu:///system",
  "session=qemu:///session"
]

# Default URI - Used when no connection is specified
# 'qemu:///system' = local system VMs (requires root)
# 'qemu:///session' = user session VMs (no root needed)
uri_default = "qemu:///system"

# Authentication - How to handle remote connections
auth_unix_ro = "polkit"    # Read-only access via polkit
auth_unix_rw = "polkit"    # Read-write access via polkit
auth_tcp = "sasl"          # TCP connections use SASL
auth_tls = "sasl"          # TLS connections use SASL

# Key files for TLS connections
key_file = "/etc/pki/libvirt/private/serverkey.pem"
cert_file = "/etc/pki/libvirt/servercert.pem"
ca_file = "/etc/pki/libvirt/cacert.pem"

Configuration Explained

URI Aliases

These create shortcuts for complex connection strings. Instead of typing:

virsh -c qemu+ssh://[email protected]/system list

You can simply use:

virsh -c hail list

Connection Types

qemu:///system - Local system VMs (requires root privileges)
qemu:///session - User session VMs (no root needed)
qemu+ssh:// - Remote VMs via SSH
qemu+tls:// - Remote VMs via TLS encryption

Authentication Methods

polkit: Uses PolicyKit for local authentication
sasl: Simple Authentication and Security Layer for remote connections
none: No authentication (not recommended for production)

Default Paths

Configuration file (unless overridden by -f):

$XDG_CONFIG_HOME/libvirt/libvirtd.conf
User-specific daemon configuration

Sockets:

$XDG_RUNTIME_DIR/libvirt/libvirt-sock
Unix domain socket for local communication

TLS Certificates:

CA certificate: $HOME/.pki/libvirt/cacert.pem
Certificate Authority for verifying server certificates
Server certificate: $HOME/.pki/libvirt/servercert.pem
Server's public certificate for TLS connections
Server private key: $HOME/.pki/libvirt/serverkey.pem
Server's private key for TLS connections

PID file (unless overridden by -p):

$XDG_RUNTIME_DIR/libvirt/libvirtd.pid
Process ID file for daemon management