Outline what the given settings influence. Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx> --- docs/kbase/debuglogs.rst | 67 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/docs/kbase/debuglogs.rst b/docs/kbase/debuglogs.rst index cba57e020d..9ba39b9f85 100644 --- a/docs/kbase/debuglogs.rst +++ b/docs/kbase/debuglogs.rst @@ -17,6 +17,73 @@ Moreover, libvirt catches stderr of all running domains. These can be useful as well. +Logging settings in libvirt +=========================== + +Log levels +---------- + +Libvirt produces log entries in 4 priority levels; higher priority level meaning +more severe log entries, which in turn means less of them. The log level are +used by `Log outputs`_ and `Log filters`_ below): + + * ``1: DEBUG`` + * ``2: INFO`` + * ``3: WARNING`` + * ``4: ERROR`` + +For debugging it's necessary to capture ``DEBUG`` level entries as the name +implies. + +Log outputs +----------- + +Log outputs describe where the log messages are being recorded. The outputs +are described by a space-separated list of tuples in the following format: + +:: + + level:output + +``level`` refers to the minimum priority level of entries recorded in the output. + +``output`` is one of the following: + + ``file:FILENAME`` + Logging messages are appended to FILENAME. + + ``journald`` + Logging goes to the ``journald`` logging daemon. + + ``stderr`` + Logging goes to the standard error output stream of the libvirt daemon. + + ``syslog:name`` + Logging goes to syslogd. ``name`` is used to identify the entries. + +The default output on systems running ``journald`` is ``3:journald``. Note that +``journald`` can trottle the amount of logs per process so for capturing debug +logs of libvirt daemons a file output should be used in addition to the output +to the logging daemon e.g.: + +:: + + "1:file:/var/log/libvirt/libvirtd.log 3:journald" + + +Log filters +----------- + +Log filters allow to avoid logging of messages which are not relevant to the +cause. The log filters is a space-separated list of tuples in the format +``level:identifer`` and limits messages which match ``identifier`` to the +configured log level. Identifier supports globbing patterns such as ``*``. + +As ``identifier`` is based on internal naming of modules, the best approach is +to select one of `Example filter settings`_. It's also always better to have +more information than lack something important. + + How to turn on debug logs for libvirt ===================================== -- 2.34.1
