Add Ntfy notification support to ZED

This commit adds the zed_notify_ntfy() function and hooks it
into zed_notify(). This will allow ZED to send notifications
to ntfy.sh or a self-hosted Ntfy service, which can be received
on a desktop or mobile device. It is configured with ZED_NTFY_TOPIC,
ZED_NTFY_URL, and ZED_NTFY_ACCESS_TOKEN variables in zed.rc.

Reviewed-by: @classabbyamp 
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Dex Wood <slash2314@gmail.com>
Closes #15584

cmd/zed/zed.d/zed-functions.sh

@@ -205,6 +205,10 @@ zed_notify()
     [ "${rv}" -eq 0 ] && num_success=$((num_success + 1))
     [ "${rv}" -eq 1 ] && num_failure=$((num_failure + 1))
 
+    zed_notify_ntfy "${subject}" "${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
@@ -527,6 +531,100 @@ zed_notify_pushover()
 }
 
 
+# zed_notify_ntfy (subject, pathname)
+#
+# Send a notification via Ntfy.sh <https://ntfy.sh/>.
+# The ntfy topic (ZED_NTFY_TOPIC) identifies the topic that the notification
+# will be sent to Ntfy.sh server. The ntfy url (ZED_NTFY_URL) defines the
+# self-hosted or provided hosted ntfy service location. The ntfy access token
+# <https://docs.ntfy.sh/publish/#access-tokens> (ZED_NTFY_ACCESS_TOKEN) reprsents an
+# access token that could be used if a topic is read/write protected. If a
+# topic can be written to publicaly, a ZED_NTFY_ACCESS_TOKEN is not required.
+#
+# Requires curl and sed executables to be installed in the standard PATH.
+#
+# References
+#   https://docs.ntfy.sh
+#
+# Arguments
+#   subject: notification subject
+#   pathname: pathname containing the notification message (OPTIONAL)
+#
+# Globals
+#   ZED_NTFY_TOPIC
+#   ZED_NTFY_ACCESS_TOKEN (OPTIONAL)
+#   ZED_NTFY_URL
+#
+# Return
+#   0: notification sent
+#   1: notification failed
+#   2: not configured
+#
+zed_notify_ntfy()
+{
+    local subject="$1"
+    local pathname="${2:-"/dev/null"}"
+    local msg_body
+    local msg_out
+    local msg_err
+
+    [ -n "${ZED_NTFY_TOPIC}" ] || return 2
+    local url="${ZED_NTFY_URL:-"https://ntfy.sh"}/${ZED_NTFY_TOPIC}"
+
+    if [ ! -r "${pathname}" ]; then
+        zed_log_err "ntfy cannot read \"${pathname}\""
+        return 1
+    fi
+
+    zed_check_cmd "curl" "sed" || return 1
+
+    # Read the message body in.
+    #
+    msg_body="$(cat "${pathname}")"
+
+    if [ -z "${msg_body}" ]
+    then
+        msg_body=$subject
+        subject=""
+    fi
+
+    # Send the POST request and check for errors.
+    #
+    if [ -n "${ZED_NTFY_ACCESS_TOKEN}" ]; then
+        msg_out="$( \
+        curl \
+        -u ":${ZED_NTFY_ACCESS_TOKEN}" \
+        -H "Title: ${subject}" \
+        -d "${msg_body}" \
+        -H "Priority: high" \
+        "${url}" \
+        2>/dev/null \
+        )"; rv=$?
+    else
+        msg_out="$( \
+        curl \
+        -H "Title: ${subject}" \
+        -d "${msg_body}" \
+        -H "Priority: high" \
+        "${url}" \
+        2>/dev/null \
+        )"; rv=$?
+    fi
+    if [ "${rv}" -ne 0 ]; then
+        zed_log_err "curl exit=${rv}"
+        return 1
+    fi
+    msg_err="$(echo "${msg_out}" \
+        | sed -n -e 's/.*"errors" *:.*\[\(.*\)\].*/\1/p')"
+    if [ -n "${msg_err}" ]; then
+        zed_log_err "ntfy \"${msg_err}"\"
+        return 1
+    fi
+    return 0
+}
+
+
+
 # zed_rate_limit (tag, [interval])
 #
 # Check whether an event of a given type [tag] has already occurred within the

cmd/zed/zed.d/zed.rc

@@ -147,3 +147,25 @@ ZED_SYSLOG_SUBCLASS_EXCLUDE="history_event"
 # help silence misbehaving drives.  This assumes your drive enclosure fully
 # supports slot power control via sysfs.
 #ZED_POWER_OFF_ENCLOUSRE_SLOT_ON_FAULT=1
+
+##
+# Ntfy topic
+# This defines which topic will receive the ntfy notification.
+#  <https://docs.ntfy.sh/publish/>
+# Disabled by default; uncomment to enable.
+#ZED_NTFY_TOPIC=""
+
+##
+# Ntfy access token (optional for public topics)
+# This defines an access token which can be used
+# to allow you to authenticate when sending to topics
+# <https://docs.ntfy.sh/publish/#access-tokens>
+# Disabled by default; uncomment to enable.
+#ZED_NTFY_ACCESS_TOKEN=""
+
+##
+# Ntfy Service URL
+# This defines which service the ntfy call will be directed toward
+#  <https://docs.ntfy.sh/install/>
+# https://ntfy.sh by default; uncomment to enable an alternative service url.
+#ZED_NTFY_URL="https://ntfy.sh"