Add MQTT backup reporting and trigger listener

lib/common.sh

@@ -16,6 +16,13 @@ WAIT_INTERVAL=3
 START_RETRIES=1
 LOCK_FILE="/run/lock/zorruno-docker-backup.lock"
 ZSTD_EXTRA_OPTS="-T0 -12"
+MQTT_REPORT_ENABLED=0
+MQTT_HOST=""
+MQTT_PORT=1883
+MQTT_USERNAME=""
+MQTT_PASSWORD_FILE=""
+MQTT_STATUS_TOPIC="viewroad-status/dockerbackup/$BACKUP_HOSTNAME"
+MQTT_COMMAND_TOPIC="viewroad-commands/dockerbackup/$BACKUP_HOSTNAME/run"
 
 RCLONE_ENABLED=0
 RCLONE_REMOTE=""
@@ -39,7 +46,12 @@ if [[ -n "${SOURCE_DIR:-}" && "$BACKUP_ROOT" == "/dockerbackups" ]]; then
 fi
 
 timestamp() { date '+%F %T'; }
-log() { printf '%s [%s] %s\n' "$(timestamp)" "$1" "$2" >&2; }
+log() {
+  local line
+  line="$(timestamp) [$1] $2"
+  printf '%s\n' "$line" >&2
+  [[ -n "${BACKUP_RUN_LOG:-}" ]] && printf '%s\n' "$line" >>"$BACKUP_RUN_LOG"
+}
 die() { log ERROR "$1"; exit "${2:-1}"; }
 
 is_true() {

lib/mqtt.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+mqtt_common_args() {
+  MQTT_ARGS=(-h "$MQTT_HOST" -p "$MQTT_PORT")
+  [[ -n "$MQTT_USERNAME" ]] && MQTT_ARGS+=(-u "$MQTT_USERNAME")
+  if [[ -n "$MQTT_PASSWORD_FILE" ]]; then
+    [[ -r "$MQTT_PASSWORD_FILE" ]] || die "MQTT password file is not readable: $MQTT_PASSWORD_FILE"
+    MQTT_ARGS+=(-P "$(<"$MQTT_PASSWORD_FILE")")
+  fi
+}
+
+mqtt_publish() {
+  local topic="$1" payload="$2" retain="${3:-0}"
+  [[ -n "$MQTT_HOST" ]] || die "MQTT_HOST is not configured"
+  require_command mosquitto_pub
+  mqtt_common_args
+  (( retain )) && MQTT_ARGS+=(-r)
+  mosquitto_pub "${MQTT_ARGS[@]}" -t "$topic" -m "$payload"
+}