Change docker log messages location - linux

Question

I met a problem with docker logging and after reading a lot of sources didn't find solution: is there a way to discard messages of docker daemon in /var/log/messages and select another location?

Answer 1

Ok, I know that this question is quite old but I don't think it has been answered well and no correct answer has been stated.
First of all the reason why it saves messages to that particular place starts in rsyslog configuration (/etc/rsyslog.conf) with the line:
$ModLoad imjournal # provides access to the systemd journal
So, because docker saves information to systemd journal it ends at /var/log/messages.
To be able to save it to other places, you have to create a rule like the following at /etc/rsyslog.d/docker.conf.
$FileCreateMode 0644
template(name="DockerLogFileName" type="list") {
constant(value="/var/log/docker/")
property(name="syslogtag" securepath="replace" \
regex.expression="docker/\\(.*\\)\\[" regex.submatch="1")
constant(value="/docker.log")
}
if $programname == 'dockerd' then \
/var/log/docker/combined.log
if $programname == 'dockerd' then \
if $syslogtag contains 'docker/' then \
?DockerLogFileName
else
/var/log/docker/no_tag/docker.log
$FileCreateMode 0600
I found the information for this configuration here:
https://www.simulmedia.com/blog/2016/02/19/centralized-docker-logging-with-rsyslog/

Answer 2

Configure rsyslog to isolate the Docker logs into their own file. To do this create /etc/rsyslog.d/10-docker.conf and copy the following content into the file.
# Docker logging
daemon.* {
/var/mylog
stop
}
In summary this will write all logs for the daemon category to /var/mylog then stop processing that log entry so it isn’t written to the systems default syslog file.

Answer 3

According to the Docker documentation, you can specify a different driver either as a command-line argument for the docker daemon or (preferably) in the daemon.json config file. Several drivers are available, e.g. for Syslog, HTTP-based logging, ...
Update
Here's an example configuration section for Syslog (from the documentation):
{
"log-driver": "syslog",
"log-opts": {
"syslog": "udp://1.2.3.4:1111"
}
}