Add ability to specify docker image in KafkaContainer. (testcontainers#580)

* Add ability to specify docker image in KafkaContainer.

* Added 'kafka.container.image' property to TestcontainersConfiguration in order to have an opportunity to replace default image with testcontainers.properties.

* Return version argument to KafkaContainer constructor.

Author: irasikhin

core/src/main/java/org/testcontainers/utility/TestcontainersConfiguration.java

@@ -50,6 +50,10 @@ public String getRyukImage() {
         return (String) properties.getOrDefault("ryuk.container.image", "bsideup/moby-ryuk:0.2.2");
     }
 
+    public String getKafkaImage() {
+        return (String) properties.getOrDefault("kafka.container.image", "confluentinc/cp-kafka");
+    }
+
     public boolean isDisableChecks() {
         return Boolean.parseBoolean((String) properties.getOrDefault("checks.disable", "false"));
     }

docs/usage/properties.md

@@ -34,5 +34,8 @@ It takes a couple of seconds, but if you want to speed up your tests, you can di
 > **compose.container.image = docker/compose:1.8.0**  
 > Used by Docker Compose integration
 
+> **kafka.container.image = confluentinc/cp-kafka**  
+> Used by KafkaContainer 
+
 Testcontainers uses public Docker images to perform different actions like startup checks, VNC recording and others.  
 Some companies disallow the usage of Docker Hub, but you can override `*.image` properties with your own images from your private registry to workaround that.

modules/kafka/src/main/java/org/testcontainers/containers/KafkaContainer.java

@@ -1,6 +1,7 @@
 package org.testcontainers.containers;
 
 import org.testcontainers.utility.Base58;
+import org.testcontainers.utility.TestcontainersConfiguration;
 
 import java.util.stream.Stream;
 
@@ -23,7 +24,7 @@ public KafkaContainer() {
     }
 
     public KafkaContainer(String confluentPlatformVersion) {
-        super("confluentinc/cp-kafka:" + confluentPlatformVersion);
+        super(TestcontainersConfiguration.getInstance().getKafkaImage() + ":" + confluentPlatformVersion);
 
         withNetwork(Network.newNetwork());
         String networkAlias = "kafka-" + Base58.randomString(6);