Use application name as default Kafka consumer group.id

Resolves quarkusio#15632
Ladicek · Mar 12, 2021 · f6db501 · f6db501
1 parent 6d7c3f8
commit f6db501
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Showing 2 changed files with 18 additions and 5 deletions.
diff --git a/docs/src/main/asciidoc/kafka.adoc b/docs/src/main/asciidoc/kafka.adoc
@@ -915,7 +915,12 @@ Type: _string_ | true |
 
 Type: _int_ | false | `1`
 
-| *group.id* | A unique string that identifies the consumer group the application belongs to. If not set, a unique, generated id is used
+| *group.id* | A unique string that identifies the consumer group the application belongs to.
+
+If not set, defaults to the application name as set by the `quarkus.application.name` configuration property.
+
+If that is not set either, a unique, generated id is used.
+It is recommended to always define a `group.id`, the automatic generation is only a convenient feature for development.
 
 Type: _string_ | false |
 

diff --git a/...ent/runtime/src/main/java/io/quarkus/kafka/client/runtime/KafkaRuntimeConfigProducer.java b/...ent/runtime/src/main/java/io/quarkus/kafka/client/runtime/KafkaRuntimeConfigProducer.java
@@ -13,32 +13,40 @@
 import org.eclipse.microprofile.config.ConfigProvider;
 
 import io.quarkus.arc.DefaultBean;
+import io.quarkus.runtime.ApplicationConfig;
 
 @Dependent
 public class KafkaRuntimeConfigProducer {
 
-    private String configPrefix = "kafka";
+    // not "kafka.", because we also inspect env vars, which start with "KAFKA_"
+    private static final String CONFIG_PREFIX = "kafka";
+
+    private static final String GROUP_ID = "group.id";
 
     @Produces
     @DefaultBean
     @ApplicationScoped
     @Named("default-kafka-broker")
-    public Map<String, Object> createKafkaRuntimeConfig() {
+    public Map<String, Object> createKafkaRuntimeConfig(ApplicationConfig app) {
         Map<String, Object> properties = new HashMap<>();
         final Config config = ConfigProvider.getConfig();
 
         StreamSupport
                 .stream(config.getPropertyNames().spliterator(), false)
                 .map(String::toLowerCase)
-                .filter(name -> name.startsWith(configPrefix))
+                .filter(name -> name.startsWith(CONFIG_PREFIX))
                 .distinct()
                 .sorted()
                 .forEach(name -> {
-                    final String key = name.substring(configPrefix.length() + 1).toLowerCase().replaceAll("[^a-z0-9.]", ".");
+                    final String key = name.substring(CONFIG_PREFIX.length() + 1).toLowerCase().replaceAll("[^a-z0-9.]", ".");
                     final String value = config.getOptionalValue(name, String.class).orElse("");
                     properties.put(key, value);
                 });
 
+        if (!properties.containsKey(GROUP_ID) && app.name.isPresent()) {
+            properties.put(GROUP_ID, app.name.get());
+        }
+
         return properties;
     }