[systemd-devel] Trying to get journalctl -M UUID to work with docker containers

[Daniel J Walsh]

On 02/08/2016 08:18 AM, Mantas Mikulėnas wrote:
> On Mon, Feb 8, 2016 at 3:09 PM, Daniel J Walsh <dwalsh at redhat.com
> <mailto:dwalsh at redhat.com>> wrote:
>
>     I have patches into docker to allow it to register with machinectl and
>     run systemd inside of the container without --privileges.  I also
>     set it
>     up so that the /var/log/journald/UUID on the host is mounted inside of
>     the container, so that journald inside of the container writes to this
>     location on the host.
>
>     Then I use journalctl -M UUID on the host to look at the host journal.
>     When I run the first container it works great.  I see the
>     container, but
>     when I run the second container, I end up seeing the first countainers
>     journal again.  If I strace journalctl -M uuid it looks like it is
>     reading all of the journals under /var/log/journalctl rather then just
>     the one for UUID.
>
>     Am I doing something wrong when I set this up?  How is this
>     supposed to
>     work?
>
>
> If I remember correctly, -M adds a filter for _MACHINE_ID and
> _BOOT_ID? Try `SYSTEMD_LOG_LEVEL=debug journalctl -M <uuid>` to
> verify. Maybe your containers actually have identical '/etc/machine-id's?
>
> -- 
> Mantas Mikulėnas <grawity at gmail.com <mailto:grawity at gmail.com>>

docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
69730c6f4b85        httpd               "/sbin/init"        7 minutes ago       Up 7 minutes        80/tcp              httpd
c8174de954b6        httpd               "/sbin/init"        22 hours ago        Up 7 minutes        80/tcp              httpd1


# machinectl 
MACHINE                          CLASS     SERVICE
69730c6f4b85ea61f5b9ddb9fb68cf7b container docker 
c8174de954b6e3037926dfa8b15cc854 container docker 


# docker exec httpd cat /etc/machine-id
69730c6f4b85ea61f5b9ddb9fb68cf7b
# docker exec httpd1 cat /etc/machine-id
c8174de954b6e3037926dfa8b15cc854



No the /etc/machine-id is different, if I enter the container I see differences.


# docker exec httpd journalctl | head -1
-- Logs begin at Mon 2016-02-08 14:10:37 UTC, end at Mon 2016-02-08 14:10:38 UTC. --
# docker exec httpd1 journalctl | head -1
-- Logs begin at Sun 2016-02-07 15:36:19 UTC, end at Mon 2016-02-08 14:10:49 UTC. --




# journalctl -M 69730c6f4b85ea61f5b9ddb9fb68cf7b  | head -1
-- Logs begin at Sun 2016-02-07 09:59:39 EST, end at Mon 2016-02-08 09:18:20 EST. --

# journalctl -M c8174de954b6e3037926dfa8b15cc854  | head -1
-- Logs begin at Sun 2016-02-07 09:59:39 EST, end at Mon 2016-02-08 09:18:40 EST. --


Where should I go for the output of this?  
SYSTEMD_LOG_LEVEL=debug journalctl -M <uuid>

Is there a way for me to see the settings of _MACHINE_ID and _BOOT_ID?  Also how can I see the actual path to the file journalctl is 
reading?  

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