send message to statsd

example.toml

@@ -7,18 +7,18 @@ hostname = "localhost"
 # Which Statsd server to send data to
 [statsd]
 hostname = "localhost"
-port = 8125             # optional, default: 8125
-prefix = "mqtt.stats"   # optional, default: "mqtt.stats"
+#port = 8125             # optional, default: 8125
+#prefix = "mqtt.stats"   # optional, default: "mqtt.stats"
 
 # List of topics to subscribe to, and corresponding stat
 [[topics]]
-mqtt_topic = "$SYS/broker/messages/publish/sent"
-statsd_topic = "publish_message_sent"
+mqtt = "$SYS/broker/messages/publish/sent"
+statsd = "publish_message_sent"
 
 [[topics]]
-mqtt_topic = "$SYS/broker/clients/connected"
-statsd_topic = "connected_clients"
+mqtt = "$SYS/broker/clients/connected"
+statsd = "connected_clients"
 
 [[topics]]
-mqtt_topic = "hello/world"
-statsd_topic = "hello_world"
+mqtt = "hello/world"
+statsd = "hello_world"

src/config.rs

@@ -46,8 +46,8 @@ pub struct StatsdConfig {
 
 #[derive(Debug, Deserialize)]
 pub struct Topic {
-    pub mqtt_topic: String,
-    pub statsd_topic: String
+    pub mqtt: String,
+    pub statsd: String
 }
 
 // =============================================================================

src/main.rs

@@ -1,9 +1,11 @@
-use std::{thread, error::Error, time::Duration};
+use std::{thread, error::Error, time::Duration, collections::HashMap};
 
 use log::{error, warn, info, debug};
 use simplelog::{ TermLogger, LevelFilter, ConfigBuilder, TerminalMode, ColorChoice};
 use paho_mqtt as paho;
 
+use statsd;
+
 mod cli_args;
 mod config;
 mod mqtt;
@@ -26,8 +28,27 @@ fn try_reconnect( mqtt: &paho::Client, timeout: u32 ) -> bool {
 
 //------------------------------------------------------------------------------
 
-fn handle_msg( msg: &paho::Message ) {
-    info!("New message: {}", msg)
+fn handle_msg(
+    msg:    &paho::Message,
+    topics: &HashMap<String, String>,
+    statsd: &statsd::Client ) {
+
+    let value = msg.payload_str().parse::<f64>();
+    if value.is_err() {
+        warn!(
+            "{}: message \"{}\" is not a number",
+            msg.topic(),
+            msg.payload_str()
+        );
+        return;
+    }
+    let value = value.unwrap();
+
+    let mqtt_topic = msg.topic();
+    let statsd_topic = topics.get(mqtt_topic).unwrap();
+
+    statsd.gauge(statsd_topic, value);
+    info!("{} ({}): {}", mqtt_topic, statsd_topic, value);
 }
 
 //------------------------------------------------------------------------------
@@ -41,6 +62,19 @@ fn main_impl( args: &cli_args::Args ) -> Result<(), Box<dyn Error>> {
     let rx = mqtt.start_consuming();
     mqtt::subscribe( &mqtt, &config.topics, args.verbose );
 
+    // init statsd
+    let statsd = statsd::Client::new(
+        format!("{}:{}", config.statsd.hostname, config.statsd.port),
+        &config.statsd.prefix
+    )?;
+
+    // MQTT -> statsd topic translation table
+    let mut topics = HashMap::new();
+    for topic in config.topics {
+        topics.insert( topic.mqtt, topic.statsd );
+    }
+    let topics = topics;
+
     // handle ^C signal to quit gracefully
     let ctrlc_mqtt = mqtt.clone();
     ctrlc::set_handler(move || {
@@ -54,7 +88,7 @@ fn main_impl( args: &cli_args::Args ) -> Result<(), Box<dyn Error>> {
         }
 
         if let Some(msg) = msg {
-            handle_msg(&msg)
+            handle_msg(&msg, &topics, &statsd);
         }
     }
 

src/mqtt.rs

@@ -30,11 +30,11 @@ pub fn create( config: &MqttConfig ) -> Result<paho::Client, paho::Error> {
 pub fn subscribe( mqtt: &paho::Client, topics: &Vec<Topic>, verbose: bool ) {
 
     for topic in topics {
-        let e = mqtt.subscribe(topic.mqtt_topic.as_str(), 1);
+        let e = mqtt.subscribe(topic.mqtt.as_str(), 1);
         if e.is_ok() {
-            info!( "Topic subscribed: \"{}\"", topic.mqtt_topic );
+            info!( "Topic subscribed: \"{}\"", topic.mqtt );
         } else if verbose {
-            warn!( "Cannot subscribe to topic \"{}\" (error: {e:?})", topic.mqtt_topic );
+            warn!( "Cannot subscribe to topic \"{}\" (error: {e:?})", topic.mqtt );
         }
     }
 }