Is there a way to make journalctl show logs from "the last time foo.service ran"?
I'm particularly interested in this for looking at the output of oneshot services that run on a timer. The --unit
flag is close, but it concatenates all the runs of the service together. The most obvious way I can think of would be to filter on PID, but that makes me worry about PID reuse / services that fork, and getting the last PID is pretty inconvenient. Is there some other identifier that corresponds to a single run of a service, that I could use to filter the logs?
EDIT: I would happily accept an authoritative "no" if that's the real answer.
Solution 1:
Since systemd
version 232
, we have the concept of invocation ID. Each time a unit is ran, it has a unique 128 bit invocation ID. Unlike MainPID
which can be recycled, or ActiveEnterTimestamp
which can have resolution troubles, it is a failsafe way to get all the log of a particular systemd unit invocation.
To obtain the latest invocation ID of a unit
$ systemctl show --value -p InvocationID openipmi
bd3eb84c3aa74169a3dcad2af183885b
To obtain the journal of the latest invocation of, say, openipmi
, whether it failed or not, you can use the one liner
$ journalctl _SYSTEMD_INVOCATION_ID=`systemctl show -p InvocationID --value openipmi.service`
-- Logs begin at Thu 2018-07-26 12:09:57 IDT, end at Mon 2019-07-08 01:32:50 IDT. --
Jun 21 13:03:13 build03.lbits openipmi[1552]: * Starting ipmi drivers
Jun 21 13:03:13 build03.lbits openipmi[1552]: ...fail!
Jun 21 13:03:13 build03.lbits openipmi[1552]: ...done.
(Note that the --value
is available since systemd 230
, older than InvocationID
)
Solution 2:
I'm not sure which timestamp makes the most sense but this works for me. Hopefully there is a better way of working with the timestamps from systemctl show
than awk - could not figure out how to control the format of timestamps.
unit=foo.service
ts=$(systemctl show -p ActiveEnterTimestamp $unit)
echo $ts
ActiveEnterTimestamp=Fri 2016-11-11 12:30:01 MST
journalctl -u $unit --since "$(echo $ts | awk '{print $2 $3}')"