Remove the clone container even when the deploy is cancelled (closes #215)

The deferred removal used the deploy context, so a cancelled deploy
(a newer push, or the build timeout) never sent the remove request and
left the clone container and its volume behind. It now uses
context.WithoutCancel, and the test gains a case that cancels the
context while the clone is running.

Model: opus-5-5

TODO.md

@@ -20,6 +20,9 @@ regress.
 
 # Completed Steps
 
+- 2026-09-23: The git clone container is now removed together with its anonymous
+  volume (the `alpine/git` image declares one at `/git`), so a deploy no longer
+  leaves a Docker volume behind (#215).
 - 2026-09-23: Fixed the flaky `t.TempDir` cleanup race in `internal/handlers`
   (the one fixed in `internal/service/webhook` by #198):
   `TestHandleWebhookProcessesValidWebhook` now waits with the webhook service's

internal/docker/client.go

@@ -656,11 +656,14 @@ func (c *Client) performClone(
 		return nil, err
 	}
 
+	// The git image declares a volume, so Docker gives each clone container
+	// an anonymous volume; remove it with the container. The removal must
+	// still run when the deploy is cancelled.
 	defer func() {
 		_ = c.docker.ContainerRemove(
-			ctx,
+			context.WithoutCancel(ctx),
 			gitContainerID.String(),
-			container.RemoveOptions{Force: true},
+			container.RemoveOptions{Force: true, RemoveVolumes: true},
 		)
 	}()
 

internal/docker/validation_test.go

@@ -1,9 +1,18 @@
 package docker //nolint:testpackage // tests unexported regexps and Client struct
 
 import (
+	"context"
 	"errors"
+	"fmt"
 	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"path/filepath"
+	"strings"
 	"testing"
+
+	"github.com/docker/docker/client"
 )
 
 // mainBranch is the branch name used across validation tests.
@@ -149,3 +158,84 @@ func TestCloneRepoRejectsInjection(t *testing.T) {
 		})
 	}
 }
+
+// TestPerformCloneRemovesContainerVolumes runs a clone against a fake Docker
+// API and checks that the clone container is removed together with its
+// anonymous volumes, whether the clone succeeds, fails, or is cancelled.
+func TestPerformCloneRemovesContainerVolumes(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		exitCode int
+		cancel   bool
+	}{
+		{name: "succeeds", exitCode: 0},
+		{name: "fails", exitCode: 1},
+		{name: "cancelled", cancel: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			ctx, cancel := context.WithCancel(t.Context())
+			t.Cleanup(cancel)
+
+			removeQuery := make(chan url.Values, 1)
+
+			srv := httptest.NewServer(http.HandlerFunc(
+				func(w http.ResponseWriter, r *http.Request) {
+					w.Header().Set("Content-Type", "application/json")
+
+					switch {
+					case r.Method == http.MethodDelete:
+						removeQuery <- r.URL.Query()
+					case strings.HasSuffix(r.URL.Path, "/containers/create"):
+						_, _ = w.Write([]byte(`{"Id":"gitcontainer"}`))
+					case strings.HasSuffix(r.URL.Path, "/wait") && tt.cancel:
+						// Cancel the deploy while the clone is running.
+						cancel()
+						<-r.Context().Done()
+					case strings.HasSuffix(r.URL.Path, "/wait"):
+						_, _ = fmt.Fprintf(w, `{"StatusCode":%d}`, tt.exitCode)
+					default:
+						_, _ = w.Write([]byte(`{}`))
+					}
+				},
+			))
+			t.Cleanup(srv.Close)
+
+			dockerAPI, err := client.NewClientWithOpts(
+				client.WithHost("tcp://" + srv.Listener.Addr().String()),
+			)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			c := &Client{docker: dockerAPI, log: slog.Default()}
+
+			dir := t.TempDir()
+			cfg := &cloneConfig{
+				repoURL:       "git@example.com:repo.git",
+				branch:        mainBranch,
+				sshPrivateKey: "fake-key",
+				containerDir:  filepath.Join(dir, "repo"),
+				hostDir:       filepath.Join(dir, "repo"),
+				keyFile:       filepath.Join(dir, "deploy_key"),
+				hostKeyFile:   filepath.Join(dir, "deploy_key"),
+			}
+
+			_, _ = c.performClone(ctx, cfg)
+
+			select {
+			case query := <-removeQuery:
+				if query.Get("v") != "1" {
+					t.Errorf("clone container removed without its volumes: %v", query)
+				}
+			default:
+				t.Error("clone container was not removed")
+			}
+		})
+	}
+}