Support docker socket overrides to be set in ~/.testcontainers.properties

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

@@ -70,6 +70,11 @@ public TransportConfig getTransportConfig() {
             .build();
     }
 
+    @Override
+    public String getRemoteDockerUnixSocketPath() {
+        return getSetting("docker.socket.override").orElse(null);
+    }
+
     @Override
     protected int getPriority() {
         return PRIORITY;

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

@@ -96,6 +96,39 @@ public void testWhenDockerHostPresent() {
         assertThat(transportConfig.getSslConfig()).isEqualTo(defaultSSLConfig);
     }
 
+    @Test
+    public void testWhenDockerSocketPresent() {
+        Mockito
+            .doReturn("auto")
+            .when(TestcontainersConfiguration.getInstance())
+            .getEnvVarOrProperty(eq("dockerconfig.source"), anyString());
+        Mockito
+            .doReturn(null)
+            .when(TestcontainersConfiguration.getInstance())
+            .getEnvVarOrUserProperty(eq("docker.host"), isNull());
+        Mockito
+            .doReturn(null)
+            .when(TestcontainersConfiguration.getInstance())
+            .getEnvVarOrUserProperty(eq("docker.tls.verify"), isNull());
+        Mockito
+            .doReturn(null)
+            .when(TestcontainersConfiguration.getInstance())
+            .getEnvVarOrUserProperty(eq("docker.cert.path"), isNull());
+        Mockito
+            .doReturn("/var/run/docker-alt.sock")
+            .when(TestcontainersConfiguration.getInstance())
+            .getEnvVarOrUserProperty(eq("docker.socket.override"), isNull());
+
+        EnvironmentAndSystemPropertyClientProviderStrategy strategy = new EnvironmentAndSystemPropertyClientProviderStrategy();
+
+        TransportConfig transportConfig = strategy.getTransportConfig();
+        assertThat(transportConfig.getDockerHost().toString()).isEqualTo(defaultDockerHost);
+        assertThat(transportConfig.getSslConfig()).isEqualTo(defaultSSLConfig);
+
+        String remoteDockerUnixSocketPath = strategy.getRemoteDockerUnixSocketPath();
+        assertThat(remoteDockerUnixSocketPath).isEqualTo("/var/run/docker-alt.sock");
+    }
+
     @Test
     public void testWhenDockerHostAndSSLConfigPresent() throws IOException {
         Path tempDir = Files.createTempDirectory("testcontainers-test");

docs/features/configuration.md

@@ -121,9 +121,10 @@ illustrates usage:
 
 ```properties
 docker.client.strategy=org.testcontainers.dockerclient.EnvironmentAndSystemPropertyClientProviderStrategy
-docker.host=tcp\://my.docker.host\:1234     # Equivalent to the DOCKER_HOST environment variable. Colons should be escaped.
-docker.tls.verify=1                         # Equivalent to the DOCKER_TLS_VERIFY environment variable
-docker.cert.path=/some/path                 # Equivalent to the DOCKER_CERT_PATH environment variable
+docker.host=tcp\://my.docker.host\:1234         # Equivalent to the DOCKER_HOST environment variable. Colons should be escaped.
+docker.socket.override=/var/run/docker-alt.sock # Equivalent to the TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE environment variable.
+docker.tls.verify=1                             # Equivalent to the DOCKER_TLS_VERIFY environment variable
+docker.cert.path=/some/path                     # Equivalent to the DOCKER_CERT_PATH environment variable
 ```
 In addition, you can deactivate this behaviour by specifying:
 ```properties