feat(config): support docker.socket.override in properties file

core/src/main/java/org/testcontainers/DockerClientFactory.java

@@ -164,7 +164,7 @@ public TransportConfig getTransportConfig() {
     public String getRemoteDockerUnixSocketPath() {
         DockerClientProviderStrategy strategy = getOrInitializeStrategy();
         if (strategy.allowUserOverrides()) {
-            String dockerSocketOverride = System.getenv("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE");
+            String dockerSocketOverride = TestcontainersConfiguration.getInstance().getDockerSocketOverride();
             if (!StringUtils.isBlank(dockerSocketOverride)) {
                 return dockerSocketOverride;
             }

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

@@ -224,6 +224,32 @@ public Integer getClientPingTimeout() {
         return Integer.parseInt(getEnvVarOrProperty("client.ping.timeout", "10"));
     }
 
+    /**
+     * Gets the Docker socket override path from configuration.
+     * <p>
+     * This method checks for the Docker socket override in the following order:
+     * <ol>
+     *   <li>{@code TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE} environment variable (if not empty)</li>
+     *   <li>{@code docker.socket.override} property from {@code ~/.testcontainers.properties}</li>
+     *   <li>{@code DOCKER_SOCKET_OVERRIDE} environment variable (unprefixed)</li>
+     * </ol>
+     * </p>
+     *
+     * @return the configured Docker socket override path, or {@code null} if not set
+     */
+    @UnstableAPI
+    public String getDockerSocketOverride() {
+        // Special handling similar to docker.client.strategy
+        // Looks for TESTCONTAINERS_ prefixed env var only
+        String prefixedEnvVarOverride = environment.get("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE");
+        if (prefixedEnvVarOverride != null && !prefixedEnvVarOverride.isEmpty()) {
+            return prefixedEnvVarOverride;
+        }
+
+        // looks for unprefixed env var or unprefixed property, or null if not set
+        return getEnvVarOrUserProperty("docker.socket.override", null);
+    }
+
     @Nullable
     @Contract("_, !null, _ -> !null")
     private String getConfigurable(

core/src/test/java/org/testcontainers/utility/TestcontainersConfigurationTest.java

@@ -225,6 +225,56 @@ void shouldTrimImageNames() {
             .isEqualTo("testcontainers/ryuk:0.3.2");
     }
 
+    @Test
+    void shouldReadDockerSocketOverrideFromEnvironment() {
+        assertThat(newConfig().getDockerSocketOverride()).as("no docker socket override by default").isNull();
+
+        environment.put("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE", "/var/run/docker.sock");
+        assertThat(newConfig().getDockerSocketOverride())
+            .as("docker socket override read from environment variable")
+            .isEqualTo("/var/run/docker.sock");
+    }
+
+    @Test
+    void shouldReadDockerSocketOverrideFromUserProperties() {
+        assertThat(newConfig().getDockerSocketOverride()).as("no docker socket override by default").isNull();
+
+        userProperties.setProperty("docker.socket.override", "/var/run/docker.sock");
+        assertThat(newConfig().getDockerSocketOverride())
+            .as("docker socket override read from user properties")
+            .isEqualTo("/var/run/docker.sock");
+    }
+
+    @Test
+    void shouldNotReadDockerSocketOverrideFromClasspathProperties() {
+        assertThat(newConfig().getDockerSocketOverride()).as("no docker socket override by default").isNull();
+
+        classpathProperties.setProperty("docker.socket.override", "/var/run/docker.sock");
+        assertThat(newConfig().getDockerSocketOverride())
+            .as("docker socket override not read from classpath properties")
+            .isNull();
+    }
+
+    @Test
+    void shouldApplyDockerSocketOverridePrecedenceOrder() {
+        userProperties.setProperty("docker.socket.override", "/var/run/user.sock");
+        environment.put("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE", "/var/run/env.sock");
+
+        assertThat(newConfig().getDockerSocketOverride())
+            .as("environment variable takes precedence over user property")
+            .isEqualTo("/var/run/env.sock");
+    }
+
+    @Test
+    void shouldTreatBlankEnvironmentVariableAsUnset() {
+        userProperties.setProperty("docker.socket.override", "/var/run/docker.sock");
+        environment.put("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE", "");
+
+        assertThat(newConfig().getDockerSocketOverride())
+            .as("blank environment variable should fall back to user property")
+            .isEqualTo("/var/run/docker.sock");
+    }
+
     private TestcontainersConfiguration newConfig() {
         return new TestcontainersConfiguration(userProperties, classpathProperties, environment);
     }