Reconnect to MQTT broker manually until we've connected once

Fixes #61

Author: Jalle19

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Change log
 
+## future release
+
+* Fix automatic reconnect to MQTT broker when initial connection attempt fails (https://github.com/Jalle19/eda-modbus-bridge/issues/61)
+
 ## 2.3.0
 
 * Add initial support for MD automation units (https://github.com/Jalle19/eda-modbus-bridge/issues/58), mainly "eco mode"

eda-modbus-bridge.mjs

@@ -7,6 +7,8 @@ import { getFlagStatus, root, setFlagStatus, setSetting, summary } from './app/h
 import { publishValues, subscribeToChanges, handleMessage, publishDeviceInformation } from './app/mqtt.mjs'
 import { configureMqttDiscovery } from './app/homeassistant.mjs'
 
+const MQTT_INITIAL_RECONNECT_RETRY_INTERVAL_SECONDS = 5
+
 const argv = yargs(process.argv.slice(2))
     .usage('node $0 [options]')
     .options({
@@ -117,7 +119,25 @@ const argv = yargs(process.argv.slice(2))
                 }
             }
 
-            const mqttClient = await MQTT.connectAsync(argv.mqttBrokerUrl, clientOptions)
+            // The MQTT client handles reconnections automatically, but only after it has connected successfully once.
+            // Retry manually until we get an initial connection.
+            let mqttClient
+            let connectedOnce = false
+            const retryIntervalMs = MQTT_INITIAL_RECONNECT_RETRY_INTERVAL_SECONDS * 1000
+
+            do {
+                try {
+                    mqttClient = await MQTT.connectAsync(argv.mqttBrokerUrl, clientOptions)
+                    connectedOnce = true
+                    console.log(`Successfully connected to MQTT broker at ${argv.mqttBrokerUrl}`)
+                } catch (e) {
+                    console.error(
+                        `Failed to connect to MQTT broker: ${e.message}. Retrying in ${retryIntervalMs} milliseconds`
+                    )
+
+                    await new Promise((resolve) => setTimeout(resolve, retryIntervalMs))
+                }
+            } while (!connectedOnce)
 
             // Publish device information once only (since it doesn't change)
             await publishDeviceInformation(modbusClient, mqttClient)
@@ -145,8 +165,6 @@ const argv = yargs(process.argv.slice(2))
             mqttClient.on('reconnect', () => {
                 console.log(`Attempting to reconnect to ${argv.mqttBrokerUrl}`)
             })
-        } catch (e) {
-            console.error(`Failed to connect to MQTT broker: ${e.message}`)
-        }
+        } catch (e) {}
     }
 })()