feat: refactor network setup (#678)

fixes #645
- network should be attached as the container is started, not as a
post-start action. This will make sure port binding and exposing works
correctly.

---------

Signed-off-by: mgorsk1 <gorskimariusz13@gmail.com>

core/testcontainers/core/container.py

@@ -4,6 +4,8 @@
 from typing import TYPE_CHECKING, Optional
 
 import docker.errors
+from docker import version
+from docker.types import EndpointConfig
 from typing_extensions import Self
 
 from testcontainers.core.config import testcontainers_config as c
@@ -88,6 +90,18 @@ def start(self) -> Self:
         logger.info("Pulling image %s", self.image)
         docker_client = self.get_docker_client()
         self._configure()
+
+        network_kwargs = (
+            {
+                "network": self._network.name,
+                "networking_config": {
+                    self._network.name: EndpointConfig(version.__version__, aliases=self._network_aliases)
+                },
+            }
+            if self._network
+            else {}
+        )
+
         self._container = docker_client.run(
             self.image,
             command=self._command,
@@ -96,11 +110,11 @@ def start(self) -> Self:
             ports=self.ports,
             name=self._name,
             volumes=self.volumes,
+            **network_kwargs,
             **self._kwargs,
         )
+
         logger.info("Container started: %s", self._container.short_id)
-        if self._network:
-            self._network.connect(self._container.id, self._network_aliases)
         return self
 
     def stop(self, force=True, delete_volume=True) -> None:

core/tests/test_network.py

@@ -45,26 +45,32 @@ def test_network_create_errors():
 
 
 def test_containers_can_communicate_over_network():
-    with Network() as network:
-        with (
-            DockerContainer(NGINX_ALPINE_SLIM_IMAGE)
-            .with_name("alpine1")
-            .with_network_aliases("alpine1-alias-1", "alpine1-alias-2")
-            .with_network(network) as alpine1
-        ):
-            with (
-                DockerContainer(NGINX_ALPINE_SLIM_IMAGE)
-                .with_name("alpine2")
-                .with_network_aliases("alpine2-alias-1", "alpine2-alias-2")
-                .with_network(network) as alpine2
-            ):
-                assert_can_ping(alpine1, "alpine2")
-                assert_can_ping(alpine1, "alpine2-alias-1")
-                assert_can_ping(alpine1, "alpine2-alias-2")
-
-                assert_can_ping(alpine2, "alpine1")
-                assert_can_ping(alpine2, "alpine1-alias-1")
-                assert_can_ping(alpine2, "alpine1-alias-2")
+    with (
+        Network() as network,
+        DockerContainer(NGINX_ALPINE_SLIM_IMAGE)
+        .with_name("alpine1")
+        .with_network_aliases("alpine1-alias-1", "alpine1-alias-2")
+        .with_network(network) as alpine1,
+        DockerContainer(NGINX_ALPINE_SLIM_IMAGE)
+        .with_name("alpine2")
+        .with_network_aliases("alpine2-alias-1", "alpine2-alias-2")
+        .with_network(network) as alpine2,
+    ):
+        assert_can_ping(alpine1, "alpine2")
+        assert_can_ping(alpine1, "alpine2-alias-1")
+        assert_can_ping(alpine1, "alpine2-alias-2")
+
+        assert_can_ping(alpine2, "alpine1")
+        assert_can_ping(alpine2, "alpine1-alias-1")
+        assert_can_ping(alpine2, "alpine1-alias-2")
+
+        assert_can_request(alpine1, "alpine2")
+        assert_can_request(alpine1, "alpine2-alias-1")
+        assert_can_request(alpine1, "alpine2-alias-2")
+
+        assert_can_request(alpine2, "alpine1")
+        assert_can_request(alpine2, "alpine1-alias-1")
+        assert_can_request(alpine2, "alpine1-alias-2")
 
 
 def assert_can_ping(container: DockerContainer, remote_name: str):
@@ -73,6 +79,12 @@ def assert_can_ping(container: DockerContainer, remote_name: str):
     assert "64 bytes" in str(output)
 
 
+def assert_can_request(container: DockerContainer, remote_name: str):
+    status, output = container.exec(f"wget -qO- http://{remote_name}")
+    assert status == 0
+    assert "Welcome to nginx!" in output.decode()
+
+
 def test_network_has_labels():
     network = Network()
     try: