fix: stop racing the daemon when removing containers (#1093)

Containers set `HostConfig.AutoRemove` but act also removes them explicitly, so the two removers race and the loser logs a 409 `removal of container X is already in progress` — seen at the end of nearly every `uses: docker://` step.

The explicit remove is redundant for `docker://` steps and docker actions (`Start(true)` already awaited exit), so it's skipped. Job and service containers keep both removers — their `sleep` entrypoint needs `AutoRemove` as a fallback reaper — so there the race is inherent and `remove()` now treats `NotFound` and `Conflict` as success.

---------

Co-authored-by: bircni <bircni@icloud.com>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1093
Reviewed-by: bircni <bircni@icloud.com>
Co-authored-by: silverwind <me@silverwind.io>

act/runner/action_test.go

@@ -20,6 +20,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
 )
 
 type closerMock struct {
@@ -150,6 +151,44 @@ runs:
 	}
 }
 
+// With AutoRemove the daemon reaps the container on exit, so act must not remove it afterwards.
+func TestExecAsDockerAutoRemove(t *testing.T) {
+	orig := ContainerNewContainer
+	defer func() { ContainerNewContainer = orig }()
+
+	for _, tc := range []struct {
+		autoRemove bool
+		removes    int
+	}{
+		{false, 2}, // stale + post-run
+		{true, 1},  // post-run skipped
+	} {
+		cm := &containerMock{}
+		ContainerNewContainer = func(*container.NewContainerInput) container.ExecutionsEnvironment { return cm }
+
+		step := &stepActionRemote{
+			Step: &model.Step{ID: "1", Uses: "org/action@v1"},
+			RunContext: &RunContext{
+				Config:       &Config{AutoRemove: tc.autoRemove},
+				Run:          &model.Run{JobID: "1", Workflow: &model.Workflow{Jobs: map[string]*model.Job{"1": {}}}},
+				JobContainer: cm,
+			},
+			action: &model.Action{Runs: model.ActionRuns{Using: "docker", Image: "docker://node:14"}},
+		}
+
+		removes := 0
+		cm.On("Pull", false).Return(func(context.Context) error { return nil })
+		cm.On("Remove").Return(func(context.Context) error { removes++; return nil })
+		cm.On("Create", []string(nil), []string(nil)).Return(func(context.Context) error { return nil })
+		cm.On("Start", true).Return(func(context.Context) error { return nil })
+		cm.On("Close").Return(func(context.Context) error { return nil })
+
+		require.NoError(t, execAsDocker(context.Background(), step, "action", t.TempDir(), t.TempDir(), false))
+		cm.AssertExpectations(t)
+		assert.Equal(t, tc.removes, removes)
+	}
+}
+
 func TestActionRunner(t *testing.T) {
 	table := []struct {
 		name        string