Container ip override

core/pom.xml

@@ -54,7 +54,12 @@
             <version>3.0.2</version>
             <scope>test</scope>
         </dependency>
-
+        <dependency>
+          <groupId>com.github.stefanbirkner</groupId>
+          <artifactId>system-rules</artifactId>
+          <version>1.16.0</version>
+          <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

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

@@ -514,6 +514,9 @@ public GenericContainer withClasspathResourceMapping(String resourcePath, String
     /**
      * Get the IP address that this container may be reached on (may not be the local machine).
      *
+     * If the system property 'testcontainers.container.host' or environment variable 'TESTCONTAINERS_CONTAINER_HOST'
+     * are set, that value will be returned instead.
+     *
      * @return an IP address
      */
     public String getContainerIpAddress() {

core/src/main/java/org/testcontainers/dockerclient/DockerClientConfigUtils.java

@@ -4,6 +4,12 @@
 
 public class DockerClientConfigUtils {
     public static String getDockerHostIpAddress(DockerClientConfig config) {
+
+        String overrideContainerHost = System.getProperty("testcontainers.container.host", System.getenv("TESTCONTAINERS_CONTAINER_HOST"));
+        if (overrideContainerHost != null) {
+            return overrideContainerHost;
+        }
+
         switch (config.getUri().getScheme()) {
         case "http":
         case "https":

core/src/test/java/org/testcontainers/dockerclient/DockerClientConfigUtilsTest.java

@@ -1,13 +1,20 @@
 package org.testcontainers.dockerclient;
 
+import com.github.dockerjava.core.DockerClientConfig;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 
-import org.junit.Test;
+public class DockerClientConfigUtilsTest {
 
-import com.github.dockerjava.core.DockerClientConfig;
+    @Rule
+    public final EnvironmentVariables environmentVariables = new EnvironmentVariables();
 
-public class DockerClientConfigUtilsTest {
+    public static final String CONTAINER_HOST_SYSPROP = "testcontainers.container.host";
+    public static final String CONTAINER_HOST_ENVVAR = "TESTCONTAINERS_CONTAINER_HOST";
 
     @Test
     public void getDockerHostIpAddressShouldReturnLocalhostWhenUnixSocket() {
@@ -43,4 +50,30 @@ public void getDockerHostIpAddressShouldReturnNullWhenUnsupportedUriScheme() {
         String actual = DockerClientConfigUtils.getDockerHostIpAddress(configuration);
         assertNull(actual);
     }
+
+    @Test
+    public void getDockerHostIpAddressShouldReturnOverrideWhenSystemPropertyIsSet() {
+        DockerClientConfig configuration = DockerClientConfig.createDefaultConfigBuilder().withUri("unix:///var/run/docker.sock").build();
+        try {
+            System.setProperty(CONTAINER_HOST_SYSPROP, "12.23.34.45");
+            String actual = DockerClientConfigUtils.getDockerHostIpAddress(configuration);
+            assertEquals("12.23.34.45", actual);
+
+        } finally {
+            System.clearProperty(CONTAINER_HOST_SYSPROP);
+        }
+    }
+
+    @Test
+    public void getDockerHostIpAddressShouldReturnOverrideWhenEnvVarIsSet() {
+        DockerClientConfig configuration = DockerClientConfig.createDefaultConfigBuilder().withUri("unix:///var/run/docker.sock").build();
+        try {
+            environmentVariables.set(CONTAINER_HOST_ENVVAR, "12.23.34.45");
+            String actual = DockerClientConfigUtils.getDockerHostIpAddress(configuration);
+            assertEquals("12.23.34.45", actual);
+
+        } finally {
+            environmentVariables.set(CONTAINER_HOST_ENVVAR, null);
+        }
+    }
 }