fix(core): Determine docker socket for rootless docker

fixes #537

Author: CarliJoy

core/testcontainers/core/config.py

@@ -6,6 +6,8 @@
 from pathlib import Path
 from typing import Optional, Union
 
+import docker
+
 
 class ConnectionMode(Enum):
     bridge_ip = "bridge_ip"
@@ -24,14 +26,30 @@ def use_mapped_port(self) -> bool:
         return True
 
 
+def get_docker_socket() -> str:
+    """
+    Determine the docker socket, prefer value given by env variable
+
+    Using the docker api ensure we handle rootless docker properly
+    """
+    if socket_path := environ.get("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE"):
+        return socket_path
+
+    client = docker.from_env()
+    try:
+        return client.api.get_adapter(client.api.base_url).socket_path
+    except AttributeError:
+        return "/var/run/docker.sock"
+
+
 MAX_TRIES = int(environ.get("TC_MAX_TRIES", 120))
 SLEEP_TIME = int(environ.get("TC_POOLING_INTERVAL", 1))
 TIMEOUT = MAX_TRIES * SLEEP_TIME
 
 RYUK_IMAGE: str = environ.get("RYUK_CONTAINER_IMAGE", "testcontainers/ryuk:0.8.1")
 RYUK_PRIVILEGED: bool = environ.get("TESTCONTAINERS_RYUK_PRIVILEGED", "false") == "true"
 RYUK_DISABLED: bool = environ.get("TESTCONTAINERS_RYUK_DISABLED", "false") == "true"
-RYUK_DOCKER_SOCKET: str = environ.get("TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE", "/var/run/docker.sock")
+RYUK_DOCKER_SOCKET: str = get_docker_socket()
 RYUK_RECONNECTION_TIMEOUT: str = environ.get("RYUK_RECONNECTION_TIMEOUT", "10s")
 TC_HOST_OVERRIDE: Optional[str] = environ.get("TC_HOST", environ.get("TESTCONTAINERS_HOST_OVERRIDE"))