fix: preserve unix socket schema in testcontainers host from properties (#3213)

This fix addresses an issue where unix socket URLs like 'unix:///var/run/docker.sock'
would have their schema stripped when parsed through testcontainersHostFromProperties,
causing Docker client initialization to fail.

The solution validates the URL format but preserves the original URL with schema
for Docker client compatibility, while maintaining backward compatibility for
other use cases.

- Fix testcontainersHostFromProperties to preserve unix socket schema
- Add comprehensive test coverage for unix socket handling
- Ensure TCP hosts continue to work as expected

Co-authored-by: Manuel de la Peña <[email protected]>

Author: knqyf263

internal/core/docker_host.go

@@ -298,12 +298,14 @@ func testcontainersHostFromProperties(_ context.Context) (string, error) {
 	cfg := config.Read()
 	testcontainersHost := cfg.TestcontainersHost
 	if testcontainersHost != "" {
-		parsed, err := parseURL(testcontainersHost)
+		// Validate the URL format
+		_, err := parseURL(testcontainersHost)
 		if err != nil {
 			return "", err
 		}
 
-		return parsed, nil
+		// Return the original URL to preserve schema for Docker client
+		return testcontainersHost, nil
 	}
 
 	return "", ErrTestcontainersHostNotSetInProperties

internal/core/docker_host_test.go

@@ -177,13 +177,26 @@ func TestExtractDockerHost(t *testing.T) {
 		t.Cleanup(resetSocketOverrideFn)
 
 		t.Run("Testcontainers host is defined in properties", func(t *testing.T) {
-			content := "tc.host=" + testRemoteHost
+			t.Run("TCP host", func(t *testing.T) {
+				content := "tc.host=" + testRemoteHost
 
-			setupTestcontainersProperties(t, content)
+				setupTestcontainersProperties(t, content)
 
-			socket, err := testcontainersHostFromProperties(context.Background())
-			require.NoError(t, err)
-			require.Equal(t, testRemoteHost, socket)
+				socket, err := testcontainersHostFromProperties(context.Background())
+				require.NoError(t, err)
+				require.Equal(t, testRemoteHost, socket)
+			})
+
+			t.Run("Unix socket host preserves schema", func(t *testing.T) {
+				unixSocket := "unix:///var/run/docker.sock"
+				content := "tc.host=" + unixSocket
+
+				setupTestcontainersProperties(t, content)
+
+				socket, err := testcontainersHostFromProperties(context.Background())
+				require.NoError(t, err)
+				require.Equal(t, unixSocket, socket)
+			})
 		})
 
 		t.Run("Testcontainers host is not defined in properties", func(t *testing.T) {