Use random string instead of container ID in Kafka client id.

Reliably getting the container ID is too expensive.
Having the K8s pod name in the Kafka client id should be enough in
most cases to associate a client id with the place where it is used.

Signed-off-by: Carsten Lohmann <carsten.lohmann@bosch.io>

clients/kafka-common/src/main/java/org/eclipse/hono/client/kafka/AbstractKafkaConfigProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022 Contributors to the Eclipse Foundation
+ * Copyright (c) 2021, 2023 Contributors to the Eclipse Foundation
  *
  * See the NOTICE file(s) distributed with this work for additional
  * information regarding copyright ownership.
@@ -21,7 +21,6 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 import org.apache.kafka.clients.CommonClientConfigs;
-import org.eclipse.hono.util.KubernetesContainerUtil;
 import org.eclipse.hono.util.Strings;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -33,6 +32,8 @@ public abstract class AbstractKafkaConfigProperties {
 
     private static final AtomicInteger ID_COUNTER = new AtomicInteger();
 
+    private static final String COMPONENT_UID_DEFAULT = getK8sComponentUId();
+
     /**
      * A logger to be shared with subclasses.
      */
@@ -50,15 +51,15 @@ public abstract class AbstractKafkaConfigProperties {
      * Creates a new instance.
      */
     protected AbstractKafkaConfigProperties() {
-        this.componentUId = getComponentUIdFromEnv();
+        this.componentUId = COMPONENT_UID_DEFAULT;
     }
 
-    private String getComponentUIdFromEnv() {
-        final String k8sContainerId = KubernetesContainerUtil.getContainerId();
-        if (k8sContainerId != null && k8sContainerId.length() >= 12) {
+    private static String getK8sComponentUId() {
+        if (System.getenv("KUBERNETES_SERVICE_HOST") != null) {
             // running in Kubernetes: use HOSTNAME env var containing the pod name
             final String podName = System.getenv("HOSTNAME");
-            return String.format("%s_%s", podName, k8sContainerId.substring(0, 12));
+            final String random = UUID.randomUUID().toString().replaceAll("-", "").substring(0, 12);
+            return String.format("%s_%s", podName, random);
         }
         return null;
     }
@@ -88,7 +89,7 @@ protected final void setSpecificClientConfig(final Map<String, String> specificC
      * Sets the component unique ID to be included in the client ID along with a counter value.
      * <p>
      * This overrides the unique ID determined automatically in case this application is running in Kubernetes
-     * (consisting of Pod/Container ID then).
+     * (containing the Pod name then).
      * <p>
      * Setting {@code null} here means that a UUID will be used in the client ID instead of component unique ID and
      * counter value.
@@ -133,7 +134,7 @@ public String getBootstrapServers() {
      * has been applied.
      * <p>
      * It is ensured that the returned map contains a unique {@code client.id}. The client ID will be created from the
-     * given client name, followed by a unique ID (containing component identifiers if running in Kubernetes).
+     * given client name, followed by a unique ID (containing a component identifier if running in Kubernetes).
      * An already set {@code client.id} property value will be used as prefix for the client ID.
      *
      * @param clientName A name for the client to include in the added {@code client.id} property.