fix(docker_refresh): Skip recreation for unchanged images

docker_refresh_test.py

@@ -46,6 +46,7 @@ def test_discovery_filters_and_groups_replicas(selected: set[str], expected: lis
         ("app:latest", True, "False", "other"),
     ]:
         containers.append({
+            "Image": "sha256:running",
             "State": {"Running": running},
             "Config": {"Image": image, "Labels": {
                 "com.docker.compose.project": project,
@@ -60,6 +61,7 @@ def test_discovery_filters_and_groups_replicas(selected: set[str], expected: lis
     assert [project.name for project in projects] == expected
     for project in projects:
         assert project.services == {"app"}
+        assert project.running_images == {"app": {"sha256:running"}}
         assert project.files == (Path("/srv/web/compose.yml"), Path("/srv/web/override.yml"))
         assert "--env-file" in project.command()
 
@@ -104,12 +106,45 @@ def test_refresh_commands_and_current_config_filtering(tmp_path: Path, dry_run:
             "db": {"image": "db:16"},
         },
     }))
-    with patch.object(script.subprocess, "run", return_value=response) as run:
+    image_response = subprocess.CompletedProcess(args=[], returncode=0, stdout="sha256:new\n")
+    with patch.object(script.subprocess, "run", side_effect=[response, response, image_response, response]) as run:
         script.refresh_project(project=project, dry_run=dry_run)
-    assert run.call_count == (1 if dry_run else 3)
+    assert run.call_count == (1 if dry_run else 4)
     if not dry_run:
         assert run.call_args_list[1].kwargs["args"] == [*project.command(), "pull", "--policy", "always", "app"]
-        assert run.call_args_list[2].kwargs["args"] == [*project.command(), "up", "--detach", "--no-deps", "--no-build", "--pull", "never", "app"]
+        assert run.call_args_list[2].kwargs["args"] == ["docker", "image", "inspect", "--format", "{{.Id}}", "app:latest"]
+        assert run.call_args_list[3].kwargs["args"] == [*project.command(), "up", "--detach", "--no-deps", "--no-build", "--pull", "never", "app"]
+
+
+@pytest.mark.parametrize("running_images, expected_services", [
+    ({"app": {"sha256:current"}, "worker": {"sha256:current"}}, []),
+    ({"app": {"sha256:old"}, "worker": {"sha256:current"}}, ["app"]),
+    ({"app": {"sha256:current", "sha256:old"}, "worker": {"sha256:current"}}, ["app"]),
+    ({"app": {"sha256:old"}, "worker": {"sha256:old"}}, ["app", "worker"]),
+])
+def test_only_changed_services_are_redeployed(
+    tmp_path: Path, running_images: dict[str, set[str]], expected_services: list[str],
+) -> None:
+    compose = tmp_path / "compose.yml"
+    compose.touch()
+    project = script.Project(
+        name="web", directory=tmp_path, files=(compose,), environment_files=(),
+        services={"app", "worker"}, running_images=running_images,
+    )
+    configuration = subprocess.CompletedProcess(args=[], returncode=0, stdout=json.dumps({
+        "services": {"app": {"image": "app:latest"}, "worker": {"image": "worker:latest"}},
+    }))
+    image_response = subprocess.CompletedProcess(args=[], returncode=0, stdout="sha256:current\n")
+    with patch.object(script.subprocess, "run", side_effect=[
+        configuration, configuration, image_response, image_response, configuration,
+    ]) as run:
+        script.refresh_project(project=project, dry_run=False)
+    assert run.call_args_list[1].kwargs["args"] == [*project.command(), "pull", "--policy", "always", "app", "worker"]
+    assert run.call_count == (5 if expected_services else 4)
+    if expected_services:
+        assert run.call_args.kwargs["args"] == [
+            *project.command(), "up", "--detach", "--no-deps", "--no-build", "--pull", "never", *expected_services,
+        ]
 
 
 @pytest.mark.parametrize("build", [".", {"context": "."}])