Allow to limit zed's syslog chattiness

Some usage patterns like send/recv of replication streams can
produce a large number of events. In such a case, the current
all-syslog.sh zedlet will hold up to its name, and flood the
logs with mostly redundant information. Two mitigate this
situation, this changeset introduces to new variables
ZED_SYSLOG_SUBCLASS_INCLUDE and ZED_SYSLOG_SUBCLASS_EXCLUDE
to zed.rc that give more control over which event classes end
up in the syslog.

Reviewed-by: loli10K <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Giuseppe Di Natale <[email protected]>
Signed-off-by: Tony Hutter <[email protected]>
Signed-off-by: Daniel Kobras <[email protected]>
Closes #6886 
Closes #7260 

4 files changed, 35 insertions, 0 deletions

diff --git a/cmd/zed/zed.d/all-debug.sh b/cmd/zed/zed.d/all-debug.sh
index 057e39b50..14b39caac 100755
--- a/cmd/zed/zed.d/all-debug.sh
+++ b/cmd/zed/zed.d/all-debug.sh
@@ -10,6 +10,8 @@
 
 : "${ZED_DEBUG_LOG:="${TMPDIR:="/tmp"}/zed.debug.log"}"
 
+zed_exit_if_ignoring_this_event
+
 lockfile="$(basename -- "${ZED_DEBUG_LOG}").lock"
 
 umask 077
diff --git a/cmd/zed/zed.d/all-syslog.sh b/cmd/zed/zed.d/all-syslog.sh
index 68d3cf360..cb9286500 100755
--- a/cmd/zed/zed.d/all-syslog.sh
+++ b/cmd/zed/zed.d/all-syslog.sh
@@ -5,6 +5,8 @@
 [ -f "${ZED_ZEDLET_DIR}/zed.rc" ] && . "${ZED_ZEDLET_DIR}/zed.rc"
 . "${ZED_ZEDLET_DIR}/zed-functions.sh"
 
+zed_exit_if_ignoring_this_event
+
 zed_log_msg "eid=${ZEVENT_EID}" "class=${ZEVENT_SUBCLASS}" \
     "${ZEVENT_POOL_GUID:+"pool_guid=${ZEVENT_POOL_GUID}"}" \
     "${ZEVENT_VDEV_PATH:+"vdev_path=${ZEVENT_VDEV_PATH}"}" \
diff --git a/cmd/zed/zed.d/zed-functions.sh b/cmd/zed/zed.d/zed-functions.sh
index ed6a95914..fb16e9d36 100644
--- a/cmd/zed/zed.d/zed-functions.sh
+++ b/cmd/zed/zed.d/zed-functions.sh
@@ -438,3 +438,23 @@ zed_guid_to_pool()
 		$ZPOOL get -H -ovalue,name guid | awk '$1=='"$guid"' {print $2}'
 	fi
 }
+
+# zed_exit_if_ignoring_this_event
+#
+# Exit the script if we should ignore this event, as determined by
+# $ZED_SYSLOG_SUBCLASS_INCLUDE and $ZED_SYSLOG_SUBCLASS_EXCLUDE in zed.rc.
+# This function assumes you've imported the normal zed variables.
+zed_exit_if_ignoring_this_event()
+{
+	if [ -n "${ZED_SYSLOG_SUBCLASS_INCLUDE}" ]; then
+	    eval "case ${ZEVENT_SUBCLASS} in
+	    ${ZED_SYSLOG_SUBCLASS_INCLUDE});;
+	    *) exit 0;;
+	    esac"
+	elif [ -n "${ZED_SYSLOG_SUBCLASS_EXCLUDE}" ]; then
+	    eval "case ${ZEVENT_SUBCLASS} in
+	    ${ZED_SYSLOG_SUBCLASS_EXCLUDE}) exit 0;;
+	    *);;
+	    esac"
+	fi
+}
diff --git a/cmd/zed/zed.d/zed.rc b/cmd/zed/zed.d/zed.rc
index 8b0e476d5..35a4d1275 100644
--- a/cmd/zed/zed.d/zed.rc
+++ b/cmd/zed/zed.d/zed.rc
@@ -100,3 +100,14 @@ ZED_USE_ENCLOSURE_LEDS=1
 #
 #ZED_SYSLOG_TAG="zed"
 
+##
+# Which set of event subclasses to log
+# By default, events from all subclasses are logged.
+# If ZED_SYSLOG_SUBCLASS_INCLUDE is set, only subclasses
+# matching the pattern are logged. Use the pipe symbol (|)
+# or shell wildcards (*, ?) to match multiple subclasses.
+# Otherwise, if ZED_SYSLOG_SUBCLASS_EXCLUDE is set, the
+# matching subclasses are excluded from logging.
+#ZED_SYSLOG_SUBCLASS_INCLUDE="checksum|scrub_*|vdev.*"
+#ZED_SYSLOG_SUBCLASS_EXCLUDE="statechange|config_*|history_event"
+