Merge pull request #1088 from lisongmin/feat-default-net-behavior-compat

Support docker-compose like default network behavior

docs/Extensions.md

@@ -110,6 +110,26 @@ x-podman:
 By default `default_net_name_compat` is `false`. This will change to `true` at some point and the
 setting will be removed.
 
+## Compatibility of default network behavior between docker-compose and podman-compose
+
+When there is no network defined (neither network-mode nor networks) in service,
+The behavior of default network in docker-compose and podman-compose are different.
+
+| Top-level networks             | podman-compose             | docker-compose |
+| ------------------------------ | -------------------------- | -------------- |
+| No networks                    | default                    | default        |
+| One network named net0         | net0                       | default        |
+| Two networks named net0, net1  | podman(`--network=bridge`) | default        |
+| Contains network named default | default                    | default        |
+
+To enable compatibility between docker-compose and podman-compose, specify
+`default_net_behavior_compat: true` under global `x-podman` key:
+
+```yaml
+x-podman:
+    default_net_behavior_compat: true
+```
+
 ## Custom pods management
 
 Podman-compose can have containers in pods. This can be controlled by extension key x-podman in_pod.

newsfragments/default_net_behavior_compat.feature

@@ -0,0 +1,2 @@
+Support docker-compose like default network behavior when no network defined in service via `default_net_behavior_compat` feature flag.
+

podman_compose.py

@@ -1998,13 +1998,23 @@ class PodmanCompose:
         nets = compose.get("networks", {})
         if not nets:
             nets["default"] = None
+
         self.networks = nets
-        if len(self.networks) == 1:
+        if compose.get("x-podman", {}).get("default_net_behavior_compat", False):
-            self.default_net = list(nets.keys())[0]
+            # If there is no network_mode and networks in service,
-        elif "default" in nets:
+            # docker-compose will create default network named '<project_name>_default'
-            self.default_net = "default"
+            # and add the service to the default network.
+            # So we always set `default_net = 'default'` for compatibility
+            if "default" not in self.networks:
+                self.networks["default"] = None
         else:
-            self.default_net = None
+            if len(self.networks) == 1:
+                self.default_net = list(nets.keys())[0]
+            elif "default" in nets:
+                self.default_net = "default"
+            else:
+                self.default_net = None
+
         allnets = set()
         for name, srv in services.items():
             srv_nets = srv.get("networks", self.default_net)

tests/integration/default_net_behavior/docker-compose_no_nets.yaml

@@ -0,0 +1,4 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/

tests/integration/default_net_behavior/docker-compose_no_nets_compat.yaml

@@ -0,0 +1,7 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+x-podman:
+  default_net_behavior_compat: true

tests/integration/default_net_behavior/docker-compose_one_net.yaml

@@ -0,0 +1,7 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+networks:
+  net0: {}

tests/integration/default_net_behavior/docker-compose_one_net_compat.yaml

@@ -0,0 +1,10 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+networks:
+  net0: {}
+
+x-podman:
+  default_net_behavior_compat: true

tests/integration/default_net_behavior/docker-compose_two_nets.yaml

@@ -0,0 +1,8 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+networks:
+  net0: {}
+  net1: {}

tests/integration/default_net_behavior/docker-compose_two_nets_compat.yaml

@@ -0,0 +1,11 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+networks:
+  net0: {}
+  net1: {}
+
+x-podman:
+  default_net_behavior_compat: true

tests/integration/default_net_behavior/docker-compose_with_default.yaml

@@ -0,0 +1,9 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+networks:
+  net0: {}
+  net1: {}
+  default: {}

tests/integration/default_net_behavior/docker-compose_with_default_compat.yaml

@@ -0,0 +1,12 @@
+services:
+  web:
+    image: busybox
+    command: httpd -f -p 8123 -h /tmp/
+
+networks:
+  net0: {}
+  net1: {}
+  default: {}
+
+x-podman:
+  default_net_behavior_compat: true

tests/integration/test_podman_compose_default_net_behavior.py

@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: GPL-2.0
+
+import os
+import unittest
+
+from parameterized import parameterized
+
+from tests.integration.test_podman_compose import podman_compose_path
+from tests.integration.test_podman_compose import test_path
+from tests.integration.test_utils import RunSubprocessMixin
+
+
+def compose_yaml_path(scenario):
+    return os.path.join(
+        os.path.join(test_path(), "default_net_behavior"), f"docker-compose_{scenario}.yaml"
+    )
+
+
+class TestComposeDefaultNetBehavior(unittest.TestCase, RunSubprocessMixin):
+    @parameterized.expand([
+        ('no_nets', 'default_net_behavior_default'),
+        ('one_net', 'default_net_behavior_net0'),
+        ('two_nets', 'podman'),
+        ('with_default', 'default_net_behavior_default'),
+        ('no_nets_compat', 'default_net_behavior_default'),
+        ('one_net_compat', 'default_net_behavior_default'),
+        ('two_nets_compat', 'default_net_behavior_default'),
+        ('with_default_compat', 'default_net_behavior_default'),
+    ])
+    def test_nethost(self, scenario, default_net):
+        try:
+            self.run_subprocess_assert_returncode(
+                [podman_compose_path(), "-f", compose_yaml_path(scenario), "up", "-d"],
+            )
+
+            container_id, _ = self.run_subprocess_assert_returncode(
+                [
+                    podman_compose_path(),
+                    "-f",
+                    compose_yaml_path(scenario),
+                    "ps",
+                    "--format",
+                    '{{.ID}}',
+                ],
+            )
+            container_id = container_id.decode('utf-8').split('\n')[0]
+            output, _ = self.run_subprocess_assert_returncode(
+                [
+                    "podman",
+                    "inspect",
+                    container_id,
+                    "--format",
+                    "{{range $key, $value := .NetworkSettings.Networks }}{{ $key }}\n{{ end }}",
+                ],
+            )
+            self.assertEqual(output.decode('utf-8').strip(), default_net)
+        finally:
+            self.run_subprocess_assert_returncode([
+                podman_compose_path(),
+                "-f",
+                compose_yaml_path(scenario),
+                "down",
+                "-t",
+                "0",
+            ])