add support for extra hosts to GenericContainer

core/src/main/java/org/testcontainers/containers/GenericContainer.java

@@ -9,9 +9,11 @@
 import com.github.dockerjava.api.model.*;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
+
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 import lombok.NonNull;
+
 import org.jetbrains.annotations.Nullable;
 import org.junit.runner.Description;
 import org.rnorth.ducttape.TimeoutException;
@@ -71,6 +73,9 @@ public class GenericContainer extends FailureDetectingExternalResource implement
     @NonNull
     private List<String> portBindings = new ArrayList<>();
 
+    @NonNull
+    private List<String> extraHosts = new ArrayList<>();
+
     @NonNull
     private Future<String> image;
 
@@ -111,6 +116,7 @@ public class GenericContainer extends FailureDetectingExternalResource implement
     @Nullable
     private InspectContainerResponse containerInfo;
 
+
     private static final Set<String> AVAILABLE_IMAGE_NAME_CACHE = new HashSet<>();
     private static final RateLimiter DOCKER_CLIENT_RATE_LIMITER = RateLimiterBuilder
             .newBuilder()
@@ -336,6 +342,10 @@ private void applyConfiguration(CreateContainerCmd createCommand) {
         createCommand.withLinks(linksArray);
 
         createCommand.withPublishAllPorts(true);
+
+        String[] extraHostsArray = extraHosts.stream()
+        		 .toArray(String[]::new);
+        createCommand.withExtraHosts(extraHostsArray);
     }
 
     /**
@@ -494,6 +504,16 @@ public GenericContainer withCommand(String... commandParts) {
         return this;
     }
 
+    /**
+     * Add an extra host entry to be passed to the container
+     * @param hostname
+     * @param ipAddress
+     * @return this
+     */
+    public GenericContainer withExtraHost(String hostname, String ipAddress) {
+        this.extraHosts.add(String.format("%s:%s", hostname, ipAddress));
+        return this;
+    }
 
     /**
      * Map a resource (file or directory) on the classpath to a path inside the container.

core/src/test/java/org/testcontainers/junit/GenericContainerRuleTest.java

@@ -5,6 +5,7 @@
 import com.mongodb.client.MongoCollection;
 import com.mongodb.client.MongoDatabase;
 import com.rabbitmq.client.*;
+
 import org.bson.Document;
 import org.junit.BeforeClass;
 import org.junit.ClassRule;
@@ -22,6 +23,8 @@
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import static org.rnorth.visibleassertions.VisibleAssertions.assertEquals;
 import static org.rnorth.visibleassertions.VisibleAssertions.assertThrows;
@@ -90,6 +93,14 @@ public static void setupContent() throws FileNotFoundException {
             .withClasspathResourceMapping("mappable-resource/test-resource.txt", "/content.txt", READ_ONLY)
             .withCommand("/bin/sh", "-c", "while true; do cat /content.txt | nc -l -p 80; done");
 
+    /**
+     * Create a container with an extra host entry and expose the content of /etc/hosts for testing.
+     */
+    @ClassRule
+    public static GenericContainer alpineExtrahost = new GenericContainer("alpine:3.2")
+            .withExposedPorts(80)
+            .withExtraHost("somehost", "192.168.1.10")
+            .withCommand("/bin/sh", "-c", "while true; do cat /etc/hosts | nc -l -p 80; done");
 
     @Test
     public void simpleRedisTest() {
@@ -255,4 +266,26 @@ public void testExecInContainer() throws Exception {
             // Once they resolve the issue, this clause can be removed.
         }
     }
+
+    @Test
+    public void extraHostTest() throws IOException {
+        BufferedReader br = Unreliables.retryUntilSuccess(10, TimeUnit.SECONDS, () -> {
+            Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
+
+            Socket socket = new Socket(alpineExtrahost.getContainerIpAddress(), alpineExtrahost.getMappedPort(80));
+            return new BufferedReader(new InputStreamReader(socket.getInputStream()));
+        });
+
+        // read hosts file from container
+        StringBuffer hosts = new StringBuffer();
+        String line = br.readLine();
+        while (line != null) {
+            hosts.append(line);
+            hosts.append("\n");
+            line = br.readLine();
+        }
+
+        Matcher matcher = Pattern.compile("^192.168.1.10\\s.*somehost", Pattern.MULTILINE).matcher(hosts.toString());
+        assertTrue("The hosts file of container contains extra host", matcher.find());
+    }
 }