mirror_zfs/cmd/zed/zed.d/zed-functions.sh
Chris Dunlap 20967ff1a4 Replace "email" ZEDLETs with "notify" ZEDLETs
Several ZEDLETs already exist for sending email in reponse to a
particular zevent.  While email is ubiquitous, alternative methods may
be better suited for some configurations.  Instead of duplicating the
"email" ZEDLETs for every future notification method, it is preferable
to abstract the notification method into a function.  This has the
added benefit of reducing the amount of code duplicated between
ZEDLETs, and allowing related bugs to be fixed in a single location.

This commit replaces the existing "email" ZEDLETs with corresponding
"notify" ZEDLETs.  In addition, the ZEDLET code for sending an
email message has been moved into the zed_notify_email() function.
And this zed_notify_email() has been added to a generic zed_notify()
function for sending notifications via all available methods that
have been configured.

This commit also changes a couple of related zed.rc variables.
ZED_EMAIL_INTERVAL_SECS is changed to ZED_NOTIFY_INTERVAL_SECS,
and ZED_EMAIL_VERBOSE is changed to ZED_NOTIFY_VERBOSE.  Note that
ZED_EMAIL remains unchanged as its use is solely for the email
notification method.

Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
2015-04-27 12:08:07 -07:00

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# zed-functions.sh
#
# ZED helper functions for use in ZEDLETs
# Variable Defaults
#
: "${ZED_LOCKDIR:="/var/lock"}"
: "${ZED_NOTIFY_INTERVAL_SECS:=3600}"
: "${ZED_NOTIFY_VERBOSE:=0}"
: "${ZED_RUNDIR:="/var/run"}"
: "${ZED_SYSLOG_PRIORITY:="daemon.notice"}"
: "${ZED_SYSLOG_TAG:="zed"}"
ZED_FLOCK_FD=8
# zed_check_cmd (cmd, ...)
#
# For each argument given, search PATH for the executable command [cmd].
# Log a message if [cmd] is not found.
#
# Arguments
# cmd: name of executable command for which to search
#
# Return
# 0 if all commands are found in PATH and are executable
# n for a count of the command executables that are not found
#
zed_check_cmd()
{
local cmd
local rv=0
for cmd; do
if ! command -v "${cmd}" >/dev/null 2>&1; then
zed_log_err "\"${cmd}\" not installed"
rv=$((rv + 1))
fi
done
return "${rv}"
}
# zed_log_msg (msg, ...)
#
# Write all argument strings to the system log.
#
# Globals
# ZED_SYSLOG_PRIORITY
# ZED_SYSLOG_TAG
#
# Return
# nothing
#
zed_log_msg()
{
logger -p "${ZED_SYSLOG_PRIORITY}" -t "${ZED_SYSLOG_TAG}" -- "$@"
}
# zed_log_err (msg, ...)
#
# Write an error message to the system log. This message will contain the
# script name, EID, and all argument strings.
#
# Globals
# ZED_SYSLOG_PRIORITY
# ZED_SYSLOG_TAG
# ZEVENT_EID
#
# Return
# nothing
#
zed_log_err()
{
logger -p "${ZED_SYSLOG_PRIORITY}" -t "${ZED_SYSLOG_TAG}" -- "error:" \
"$(basename -- "$0"):" "${ZEVENT_EID:+"eid=${ZEVENT_EID}:"}" "$@"
}
# zed_lock (lockfile, [fd])
#
# Obtain an exclusive (write) lock on [lockfile]. If the lock cannot be
# immediately acquired, wait until it becomes available.
#
# Every zed_lock() must be paired with a corresponding zed_unlock().
#
# By default, flock-style locks associate the lockfile with file descriptor 8.
# The bash manpage warns that file descriptors >9 should be used with care as
# they may conflict with file descriptors used internally by the shell. File
# descriptor 9 is reserved for zed_rate_limit(). If concurrent locks are held
# within the same process, they must use different file descriptors (preferably
# decrementing from 8); otherwise, obtaining a new lock with a given file
# descriptor will release the previous lock associated with that descriptor.
#
# Arguments
# lockfile: pathname of the lock file; the lock will be stored in
# ZED_LOCKDIR unless the pathname contains a "/".
# fd: integer for the file descriptor used by flock (OPTIONAL unless holding
# concurrent locks)
#
# Globals
# ZED_FLOCK_FD
# ZED_LOCKDIR
#
# Return
# nothing
#
zed_lock()
{
local lockfile="$1"
local fd="${2:-${ZED_FLOCK_FD}}"
local umask_bak
local err
[ -n "${lockfile}" ] || return
if ! expr "${lockfile}" : '.*/' >/dev/null 2>&1; then
lockfile="${ZED_LOCKDIR}/${lockfile}"
fi
umask_bak="$(umask)"
umask 077
# Obtain a lock on the file bound to the given file descriptor.
#
eval "exec ${fd}> '${lockfile}'"
err="$(flock --exclusive "${fd}" 2>&1)"
if [ $? -ne 0 ]; then
zed_log_err "failed to lock \"${lockfile}\": ${err}"
fi
umask "${umask_bak}"
}
# zed_unlock (lockfile, [fd])
#
# Release the lock on [lockfile].
#
# Arguments
# lockfile: pathname of the lock file
# fd: integer for the file descriptor used by flock (must match the file
# descriptor passed to the zed_lock function call)
#
# Globals
# ZED_FLOCK_FD
# ZED_LOCKDIR
#
# Return
# nothing
#
zed_unlock()
{
local lockfile="$1"
local fd="${2:-${ZED_FLOCK_FD}}"
local err
[ -n "${lockfile}" ] || return
if ! expr "${lockfile}" : '.*/' >/dev/null 2>&1; then
lockfile="${ZED_LOCKDIR}/${lockfile}"
fi
# Release the lock and close the file descriptor.
#
err="$(flock --unlock "${fd}" 2>&1)"
if [ $? -ne 0 ]; then
zed_log_err "failed to unlock \"${lockfile}\": ${err}"
fi
eval "exec ${fd}>&-"
}
# zed_notify (subject, pathname)
#
# Send a notification via all available methods.
#
# Arguments
# subject: notification subject
# pathname: pathname containing the notification message (OPTIONAL)
#
# Return
# 0: notification succeeded via at least one method
# 1: notification failed
# 2: no notification methods configured
#
zed_notify()
{
local subject="$1"
local pathname="$2"
local num_success=0
local num_failure=0
zed_notify_email "${subject}" "${pathname}"; rv=$?
[ "${rv}" -eq 0 ] && num_success=$((num_success + 1))
[ "${rv}" -eq 1 ] && num_failure=$((num_failure + 1))
[ "${num_success}" -gt 0 ] && return 0
[ "${num_failure}" -gt 0 ] && return 1
return 2
}
# zed_notify_email (subject, pathname)
#
# Send a notification via email to the address specified by ZED_EMAIL.
#
# Requires the mail executable to be installed in the standard PATH.
#
# Arguments
# subject: notification subject
# pathname: pathname containing the notification message (OPTIONAL)
#
# Globals
# ZED_EMAIL
#
# Return
# 0: notification sent
# 1: notification failed
# 2: not configured
#
zed_notify_email()
{
local subject="$1"
local pathname="${2:-"/dev/null"}"
[ -n "${ZED_EMAIL}" ] || return 2
[ -n "${subject}" ] || return 1
if [ ! -r "${pathname}" ]; then
zed_log_err "mail cannot read \"${pathname}\""
return 1
fi
zed_check_cmd "mail" || return 1
mail -s "${subject}" "${ZED_EMAIL}" < "${pathname}" >/dev/null 2>&1; rv=$?
if [ "${rv}" -ne 0 ]; then
zed_log_err "mail exit=${rv}"
return 1
fi
return 0
}
# zed_rate_limit (tag, [interval])
#
# Check whether an event of a given type [tag] has already occurred within the
# last [interval] seconds.
#
# This function obtains a lock on the statefile using file descriptor 9.
#
# Arguments
# tag: arbitrary string for grouping related events to rate-limit
# interval: time interval in seconds (OPTIONAL)
#
# Globals
# ZED_NOTIFY_INTERVAL_SECS
# ZED_RUNDIR
#
# Return
# 0 if the event should be processed
# 1 if the event should be dropped
#
# State File Format
# time;tag
#
zed_rate_limit()
{
local tag="$1"
local interval="${2:-${ZED_NOTIFY_INTERVAL_SECS}}"
local lockfile="zed.zedlet.state.lock"
local lockfile_fd=9
local statefile="${ZED_RUNDIR}/zed.zedlet.state"
local time_now
local time_prev
local umask_bak
local rv=0
[ -n "${tag}" ] || return 0
zed_lock "${lockfile}" "${lockfile_fd}"
time_now="$(date +%s)"
time_prev="$(egrep "^[0-9]+;${tag}\$" "${statefile}" 2>/dev/null \
| tail -1 | cut -d\; -f1)"
if [ -n "${time_prev}" ] \
&& [ "$((time_now - time_prev))" -lt "${interval}" ]; then
rv=1
else
umask_bak="$(umask)"
umask 077
egrep -v "^[0-9]+;${tag}\$" "${statefile}" 2>/dev/null \
> "${statefile}.$$"
echo "${time_now};${tag}" >> "${statefile}.$$"
mv -f "${statefile}.$$" "${statefile}"
umask "${umask_bak}"
fi
zed_unlock "${lockfile}" "${lockfile_fd}"
return "${rv}"
}