feat(images): implement RemoveImage gRPC API with extra protection for used images

internal/machine/docker/image.go

@@ -0,0 +1,79 @@
+package docker
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/containerd/errdefs"
+	"github.com/distribution/reference"
+	"github.com/docker/docker/api/types/container"
+	"github.com/docker/docker/api/types/filters"
+	"github.com/docker/docker/api/types/image"
+	"github.com/docker/docker/pkg/stringid"
+	"github.com/psviderski/uncloud/pkg/api"
+)
+
+// RemoveImage removes an image while protecting names used by containers, even when force is requested.
+func (s *Service) RemoveImage(ctx context.Context, id string, opts image.RemoveOptions) ([]image.DeleteResponse, error) {
+	if err := s.checkImageRemovalConflicts(ctx, id); err != nil {
+		return nil, err
+	}
+	// Docker enforces its own conflicts, including protection of a used image's final reference.
+	return s.Client.ImageRemove(ctx, id, opts)
+}
+
+// checkImageRemovalConflicts rejects an image ID used by a running or stopped container, or a name used by a
+// container while it still resolves to that container's image. A digest request also checks the repository tags
+// Docker would remove with it. Unused aliases are allowed.
+func (s *Service) checkImageRemovalConflicts(ctx context.Context, id string) error {
+	img, err := s.Client.ImageInspect(ctx, id)
+	if err != nil {
+		return err
+	}
+	// Match Docker's resolved ID before parsing names, since a short ID also parses as a repository name.
+	isID := strings.HasPrefix(strings.TrimPrefix(img.ID, "sha256:"), strings.TrimPrefix(id, "sha256:"))
+	var named reference.Named
+	if !isID {
+		named, err = reference.ParseDockerRef(id)
+		if err != nil {
+			return errdefs.ErrInvalidArgument.WithMessage(err.Error())
+		}
+	}
+	_, isDigest := named.(reference.Canonical)
+
+	containers, err := s.Client.ContainerList(ctx, container.ListOptions{
+		All: true, Filters: filters.NewArgs(filters.Arg("ancestor", img.ID)),
+	})
+	if err != nil {
+		return fmt.Errorf("list containers using image: %w", err)
+	}
+
+	for _, ctr := range containers {
+		// The ancestor filter can include descendants. A retagged name must also be checked against its current ID.
+		if ctr.ImageID != img.ID {
+			continue
+		}
+
+		usedRef, err := reference.ParseDockerRef(ctr.Image)
+		// Familiar names make "alpine:latest" and "docker.io/library/alpine:latest" identify the same tag.
+		removesUsedName := err == nil && named != nil && reference.FamiliarString(usedRef) == reference.FamiliarString(named)
+		if isDigest && err == nil && usedRef.Name() == named.Name() {
+			// Removing a digest also removes this repository's tags pointing at the same image.
+			removesUsedName = true
+		}
+		if isID || removesUsedName {
+			ctrID, state := stringid.TruncateID(ctr.ID), "stopped"
+			if serviceName := ctr.Labels[api.LabelServiceName]; serviceName != "" {
+				ctrID = serviceName + "/" + ctrID
+			}
+			if ctr.State == container.StateRunning || ctr.State == container.StatePaused {
+				state = container.StateRunning
+			}
+			return errdefs.ErrConflict.WithMessage(
+				fmt.Sprintf("image '%s' is used by container '%s' (%s)", id, ctrID, state))
+		}
+	}
+
+	return nil
+}