kata-journald-host-redirect.service

# Copyright (c) 2019 Intel Corporation
#
# SPDX-License-Identifier: Apache-2.0

#---------------------------------------------------------------------
# Description: Systemd unit to redirect guest OS syslog (journald) logs
#   to a VSOCK server running on the host.
#
# Note: The "other side" of the VSOCK bridge (outside the virtual
#   machine) is handled by the vsock-to-text-server.sh script.
#---------------------------------------------------------------------

[Unit]
Description=Fake syslog service that redirects to the host via vsock
# Only start this service when `kernel_params` in `configuration.yaml` contains the specified systemd option
ConditionKernelCommandLine=systemd.journald.forward_to_syslog=1
Requires=syslog.socket

[Service]
Type=simple
StandardOutput=null
StandardError=null
# The horrid hex string below represents the VSOCK address with:
#
# - CID 2 (reserved for HOST)
# - port 5140 (note: 514 is syslog)
#
# This hex string is required to be passed to socat(1) since at the time of
# writing socat version 1.7.3.2 does not understand VSOCK sockets
# (but does provide this method to overcome this limitation).
#
# See:
#
# - https://gist.github.com/mcastelino/9a57d00ccf245b98de2129f0efe39857#using-specific-ports
# - http://www.dest-unreach.org/socat/doc/socat-genericsocket.html
Environment=host_vsock_addr=x00x00x14x14x00x00x02x00x00x00x00x00x00x00
# Listen on file descriptor 3, which is the first socket-activated file descriptor
# (see systemd-socket-activate(1)).
ExecStart=/bin/socat -u "fd:3" "socket-connect:40:0:${host_vsock_addr}"
LimitNOFILE=infinity
Restart=on-failure

[Install]
WantedBy=kata-containers.target
Alias=syslog.service