zed: Add Pushover notifier

Add zed_notify_pushover to zed-functions.sh, along with the necessary
configuration variables in zed.rc.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Signed-off-by: Scott Colby <scott@scolby.com>
Closes #12012

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

@@ -202,6 +202,10 @@ zed_notify()
     [ "${rv}" -eq 0 ] && num_success=$((num_success + 1))
     [ "${rv}" -eq 1 ] && num_failure=$((num_failure + 1))
 
+    zed_notify_pushover "${subject}" "${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
@@ -433,6 +437,84 @@ zed_notify_slack_webhook()
     return 0
 }
 
+# zed_notify_pushover (subject, pathname)
+#
+# Send a notification via Pushover <https://pushover.net/>.
+# The access token (ZED_PUSHOVER_TOKEN) identifies this client to the
+# Pushover server. The user token (ZED_PUSHOVER_USER) defines the user or
+# group to which the notification will be sent.
+#
+# Requires curl and sed executables to be installed in the standard PATH.
+#
+# References
+#   https://pushover.net/api
+#
+# Arguments
+#   subject: notification subject
+#   pathname: pathname containing the notification message (OPTIONAL)
+#
+# Globals
+#   ZED_PUSHOVER_TOKEN
+#   ZED_PUSHOVER_USER
+#
+# Return
+#   0: notification sent
+#   1: notification failed
+#   2: not configured
+#
+zed_notify_pushover()
+{
+    local subject="$1"
+    local pathname="${2:-"/dev/null"}"
+    local msg_body
+    local msg_out
+    local msg_err
+    local url="https://api.pushover.net/1/messages.json"
+
+    [ -n "${ZED_PUSHOVER_TOKEN}" ] && [ -n "${ZED_PUSHOVER_USER}" ] || return 2
+
+    if [ ! -r "${pathname}" ]; then
+        zed_log_err "pushover cannot read \"${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.
+    #
+    msg_out="$( \
+        curl \
+        --form-string "token=${ZED_PUSHOVER_TOKEN}" \
+        --form-string "user=${ZED_PUSHOVER_USER}" \
+        --form-string "message=${msg_body}" \
+        --form-string "title=${subject}" \
+        "${url}" \
+        2>/dev/null \
+        )"; rv=$?
+    if [ "${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 "${msg_err}" ]; then
+        zed_log_err "pushover \"${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

@@ -82,6 +82,23 @@ ZED_EMAIL_ADDR="root"
 #
 #ZED_SLACK_WEBHOOK_URL=""
 
+##
+# Pushover token.
+# This defines the application from which the notification will be sent.
+#   <https://pushover.net/api#registration>
+# Disabled by default; uncomment to enable.
+# ZED_PUSHOVER_USER, below, must also be configured.
+#
+#ZED_PUSHOVER_TOKEN=""
+
+##
+# Pushover user key.
+# This defines which user or group will receive Pushover notifications.
+#  <https://pushover.net/api#identifiers>
+# Disabled by default; uncomment to enable.
+# ZED_PUSHOVER_TOKEN, above, must also be configured.
+#ZED_PUSHOVER_USER=""
+
 ##
 # Default directory for zed state files.
 #