feat(mqtt source): support multiple mqtt source topics

.github/workflows/semantic.yml

@@ -159,6 +159,7 @@ jobs:
             kubernetes_logs source
             logstash source
             mongodb_metrics source
+            mqtt source
             nats source
             new source
             nginx_metrics source

changelog.d/23670_support_many_mqtt_source_topics.enhancement.md

@@ -0,0 +1,3 @@
+The `mqtt` source config field `topic` can now be a list of mqtt topic strings instead of just a string. If a list is provided, the `mqtt` source client will subscribe to all the topics.
+
+authors: december1981

src/sources/mqtt/config.rs

@@ -20,7 +20,7 @@ use crate::{
         TlsSnafu,
     },
     config::{SourceConfig, SourceContext, SourceOutput},
-    serde::{default_decoding, default_framing_message_based},
+    serde::{OneOrMany, default_decoding, default_framing_message_based},
 };
 
 /// Configuration for the `mqtt` source.
@@ -32,11 +32,11 @@ pub struct MqttSourceConfig {
     #[serde(flatten)]
     pub common: MqttCommonConfig,
 
-    /// MQTT topic from which messages are to be read.
+    /// MQTT topic or topics from which messages are to be read.
     #[configurable(derived)]
     #[serde(default = "default_topic")]
     #[derivative(Default(value = "default_topic()"))]
-    pub topic: String,
+    pub topic: OneOrMany<String>,
 
     #[configurable(derived)]
     #[serde(default = "default_framing_message_based")]
@@ -63,8 +63,8 @@ pub struct MqttSourceConfig {
     pub topic_key: OptionalValuePath,
 }
 
-fn default_topic() -> String {
-    "vector".to_owned()
+fn default_topic() -> OneOrMany<String> {
+    OneOrMany::One("vector".into())
 }
 
 fn default_topic_key() -> OptionalValuePath {

src/sources/mqtt/integration_tests.rs

@@ -7,12 +7,13 @@ use futures::StreamExt;
 use rumqttc::{AsyncClient, MqttOptions, QoS};
 use tokio::time::timeout;
 
-use super::MqttSourceConfig;
 use crate::{
     SourceSender,
     common::mqtt::MqttCommonConfig,
     config::{SourceConfig, SourceContext, log_schema},
     event::Event,
+    serde::OneOrMany,
+    sources::mqtt::MqttSourceConfig,
     test_util::{
         components::{SOURCE_TAGS, assert_source_compliance},
         random_lines_with_stream, random_string, trace_init,
@@ -59,13 +60,13 @@ async fn get_mqtt_client() -> AsyncClient {
 }
 
 #[tokio::test]
-async fn mqtt_happy() {
+async fn mqtt_one_topic_happy() {
     trace_init();
     let topic = "source-test";
     // We always want new client ID. If it were stable, subsequent tests could receive data sent in previous runs.
     let client_id = format!("sourceTest{}", random_string(6));
     let num_events = 10;
-    let (input, _events) = random_lines_with_stream(100, num_events, None);
+    let (input, ..) = random_lines_with_stream(100, num_events, None);
 
     assert_source_compliance(&SOURCE_TAGS, async {
         let common = MqttCommonConfig {
@@ -77,7 +78,7 @@ async fn mqtt_happy() {
 
         let config = MqttSourceConfig {
             common,
-            topic: topic.to_owned(),
+            topic: OneOrMany::One(topic.to_owned()),
             ..MqttSourceConfig::default()
         };
 
@@ -116,3 +117,69 @@ async fn mqtt_happy() {
     })
     .await;
 }
+
+#[tokio::test]
+async fn mqtt_many_topics_happy() {
+    trace_init();
+    let topic_prefix_1 = "source-prefix-1";
+    let topic_prefix_2 = "source-prefix-2";
+    // We always want new client ID. If it were stable, subsequent tests could receive data sent in previous runs.
+    let client_id = format!("sourceTest{}", random_string(6));
+    let num_events = 10;
+    let (input_1, ..) = random_lines_with_stream(100, num_events, None);
+    let (input_2, ..) = random_lines_with_stream(100, num_events, None);
+
+    assert_source_compliance(&SOURCE_TAGS, async {
+        let common = MqttCommonConfig {
+            host: mqtt_broker_address(),
+            port: mqtt_broker_port(),
+            client_id: Some(client_id),
+            ..Default::default()
+        };
+
+        let config = MqttSourceConfig {
+            common,
+            topic: OneOrMany::Many(vec![
+                format!("{topic_prefix_1}/#"),
+                format!("{topic_prefix_2}/#"),
+            ]),
+            ..MqttSourceConfig::default()
+        };
+
+        let (tx, rx) = SourceSender::new_test();
+        tokio::spawn(async move {
+            config
+                .build(SourceContext::new_test(tx, None))
+                .await
+                .unwrap()
+                .await
+                .unwrap()
+        });
+
+        tokio::time::sleep(Duration::from_millis(100)).await;
+
+        let client = get_mqtt_client().await;
+        send_test_events(&client, &format!("{topic_prefix_1}/test"), &input_1).await;
+        send_test_events(&client, &format!("{topic_prefix_2}/test"), &input_2).await;
+
+        let mut expected_messages: HashSet<_> =
+            input_1.into_iter().chain(input_2.into_iter()).collect();
+
+        let events: Vec<Event> = timeout(Duration::from_secs(2), rx.take(num_events * 2).collect())
+            .await
+            .unwrap();
+
+        for event in events {
+            let message = event
+                .as_log()
+                .get(log_schema().message_key_target_path().unwrap())
+                .unwrap()
+                .to_string_lossy();
+            if !expected_messages.remove(message.as_ref()) {
+                panic!("Received unexpected message: {message:?}");
+            }
+        }
+        assert!(expected_messages.is_empty());
+    })
+    .await;
+}

src/sources/mqtt/source.rs

@@ -1,5 +1,5 @@
 use itertools::Itertools;
-use rumqttc::{Event as MqttEvent, Incoming, Publish, QoS};
+use rumqttc::{Event as MqttEvent, Incoming, Publish, QoS, SubscribeFilter};
 use vector_lib::{
     config::{LegacyKey, LogNamespace},
     internal_event::EventsReceived,
@@ -12,6 +12,7 @@ use crate::{
     common::mqtt::MqttConnector,
     event::{BatchNotifier, Event},
     internal_events::{EndpointBytesReceived, StreamClosedError},
+    serde::OneOrMany,
     shutdown::ShutdownSignal,
     sources::{mqtt::MqttSourceConfig, util},
 };
@@ -41,10 +42,25 @@ impl MqttSource {
     pub async fn run(self, mut out: SourceSender, shutdown: ShutdownSignal) -> Result<(), ()> {
         let (client, mut connection) = self.connector.connect();
 
-        client
-            .subscribe(&self.config.topic, QoS::AtLeastOnce)
-            .await
-            .map_err(|_| ())?;
+        match &self.config.topic {
+            OneOrMany::One(topic) => {
+                client
+                    .subscribe(topic, QoS::AtLeastOnce)
+                    .await
+                    .map_err(|_| ())?;
+            }
+            OneOrMany::Many(topics) => {
+                client
+                    .subscribe_many(
+                        topics
+                            .iter()
+                            .cloned()
+                            .map(|topic| SubscribeFilter::new(topic, QoS::AtLeastOnce)),
+                    )
+                    .await
+                    .map_err(|_| ())?;
+            }
+        }
 
         loop {
             tokio::select! {

website/cue/reference/components/sources/generated/mqtt.cue

@@ -639,7 +639,7 @@ generated: components: sources: mqtt: configuration: {
 		}
 	}
 	topic: {
-		description: "MQTT topic from which messages are to be read."
+		description: "MQTT topic or topics from which messages are to be read."
 		required:    false
 		type: string: default: "vector"
 	}