DEVX-26: fix: use host Docker socket with DOCKER_HOST fallback to local dockerd

src/devx/molecule/start_docker.py

@@ -1,11 +1,13 @@
 #!/usr/bin/env python3
-"""Start a Docker daemon inside a CI runner container (Docker-in-Docker).
+"""Ensure Docker is available for molecule tests in CI.
 
 CI runners (e.g. ``gitea/runner-images:ubuntu-latest``) may have the host's
-Docker socket mounted, but molecule needs a local Docker daemon to create
-nested containers. This module starts ``dockerd`` on a separate socket
-and sets ``DOCKER_HOST`` so both the CLI and Python library connect to
-the local daemon.
+Docker socket mounted. This module verifies Docker is accessible and
+sets ``DOCKER_HOST`` explicitly so molecule's Python docker library
+connects to the same socket as the Docker CLI.
+
+If the host socket is not available, it starts a local ``dockerd``
+with the vfs storage driver (requires privileged container).
 
 Usage::
 
@@ -25,11 +27,11 @@ import click
 from devx.i18n import _
 
 DEFAULT_TIMEOUT = 30
-DOCKER_SOCK = "/tmp/dockerd.sock"  # nosec B108
+DOCKER_SOCK = "/var/run/docker.sock"
 
 
 def is_docker_ready() -> bool:
-    """Check if the local Docker daemon is responding."""
+    """Check if Docker daemon is responding on the configured socket."""
     result = subprocess.run(  # nosec B603 B607
         ["docker", "info"],
         capture_output=True,
@@ -40,19 +42,24 @@ def is_docker_ready() -> bool:
 
 
 def start_docker_daemon(timeout: int = DEFAULT_TIMEOUT) -> bool:
-    """Start dockerd on a separate socket and wait for it to be ready.
+    """Ensure Docker is ready for molecule tests.
 
-    Uses ``/tmp/dockerd.sock`` instead of the default ``/var/run/docker.sock``
-    to avoid conflicts with host-mounted sockets. Sets ``DOCKER_HOST`` in the
-    current environment so molecule's Python docker library connects to the
-    local daemon.
+    First tries the host socket. If that works, sets ``DOCKER_HOST`` and
+    returns immediately. If not, starts a local ``dockerd`` with vfs
+    storage driver (requires privileged container).
 
     Returns ``True`` if Docker is ready, ``False`` if it failed to
     start within the timeout.
     """
-    # Point Docker CLI and Python library to our local socket
+    # Point Docker CLI and Python library to the socket explicitly
     os.environ["DOCKER_HOST"] = f"unix://{DOCKER_SOCK}"
 
+    # Check if host Docker is already available
+    if is_docker_ready():
+        click.echo(_("Docker daemon already running"))
+        return True
+
+    # Start local dockerd (requires privileged container)
     click.echo(_("Starting Docker daemon..."))
     log_file = tempfile.NamedTemporaryFile(  # noqa: SIM115
         mode="w", suffix="dockerd.log", delete=False

src/devx/translations.json

@@ -419,6 +419,13 @@
     "ru": "Created release commit.",
     "zh": "Created release commit."
   },
+  "Docker daemon already running": {
+    "bg": "Докер демонът вече работи",
+    "de": "Docker-Daemon läuft bereits",
+    "en": "Docker daemon already running",
+    "ru": "Демон Docker уже работает",
+    "zh": "Docker 守护进程已在运行"
+  },
   "Docker daemon failed to start": {
     "bg": "Docker daemon failed to start",
     "de": "Docker-Daemon konnte nicht gestartet werden",