Pods now return what containers were removed with them

This probably should have been in the API since the beginning,
but it's not too late to start now.

The extra information is returned (both via the REST API, and to
the CLI handler for `podman rm`) but is not yet printed - it
feels like adding it to the output could be a breaking change?

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

libpod/runtime_pod_common.go

@@ -124,8 +124,9 @@ func (r *Runtime) SavePod(pod *Pod) error {
 
 // DO NOT USE THIS FUNCTION DIRECTLY. Use removePod(), below. It will call
 // removeMalformedPod() if necessary.
-func (r *Runtime) removeMalformedPod(ctx context.Context, p *Pod, ctrs []*Container, force bool, timeout *uint, ctrNamedVolumes map[string]*ContainerNamedVolume) error {
-	var removalErr error
+func (r *Runtime) removeMalformedPod(ctx context.Context, p *Pod, ctrs []*Container, force bool, timeout *uint, ctrNamedVolumes map[string]*ContainerNamedVolume) (map[string]error, error) {
+	removedCtrs := make(map[string]error)
+	errored := false
 	for _, ctr := range ctrs {
 		err := func() error {
 			ctrLock := ctr.lock
@@ -145,15 +146,24 @@ func (r *Runtime) removeMalformedPod(ctx context.Context, p *Pod, ctrs []*Contai
 			_, _, err := r.removeContainer(ctx, ctr, force, false, true, true, false, false, timeout)
 			return err
 		}()
-
-		if removalErr == nil {
-			removalErr = err
-		} else {
-			logrus.Errorf("Removing container %s from pod %s: %v", ctr.ID(), p.ID(), err)
+		removedCtrs[ctr.ID()] = err
+		if err != nil {
+			errored = true
 		}
 	}
-	if removalErr != nil {
-		return removalErr
+
+	// So, technically, no containers have been *removed*.
+	// They're still in the DB.
+	// So just return nil for removed containers. Squash all the errors into
+	// a multierror so we don't lose them.
+	if errored {
+		var allErrors error
+		for ctr, err := range removedCtrs {
+			if err != nil {
+				allErrors = multierror.Append(allErrors, fmt.Errorf("removing container %s: %w", ctr, err))
+			}
+		}
+		return nil, fmt.Errorf("no containers were removed due to the following errors: %w", allErrors)
 	}
 
 	// Clear infra container ID before we remove the infra container.
@@ -162,7 +172,7 @@ func (r *Runtime) removeMalformedPod(ctx context.Context, p *Pod, ctrs []*Contai
 	// later - we end up with a reference to a nonexistent infra container.
 	p.state.InfraContainerID = ""
 	if err := p.save(); err != nil {
-		return err
+		return nil, err
 	}
 
 	// Remove all containers in the pod from the state.
@@ -170,20 +180,22 @@ func (r *Runtime) removeMalformedPod(ctx context.Context, p *Pod, ctrs []*Contai
 		// If this fails, there isn't much more we can do.
 		// The containers in the pod are unusable, but they still exist,
 		// so pod removal will fail.
-		return err
+		return nil, err
 	}
 
-	return nil
+	return removedCtrs, nil
 }
 
-func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool, timeout *uint) error {
+func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool, timeout *uint) (map[string]error, error) {
+	removedCtrs := make(map[string]error)
+
 	if err := p.updatePod(); err != nil {
-		return err
+		return nil, err
 	}
 
 	ctrs, err := r.state.PodContainers(p)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	numCtrs := len(ctrs)
 
@@ -194,7 +206,7 @@ func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool,
 		force = true
 	}
 	if !removeCtrs && numCtrs > 0 {
-		return fmt.Errorf("pod %s contains containers and cannot be removed: %w", p.ID(), define.ErrCtrExists)
+		return nil, fmt.Errorf("pod %s contains containers and cannot be removed: %w", p.ID(), define.ErrCtrExists)
 	}
 
 	var removalErr error
@@ -206,14 +218,15 @@ func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool,
 		// We have to allow the pod to be removed.
 		// But let's only do it if force is set.
 		if !force {
-			return fmt.Errorf("cannot create container graph for pod %s: %w", p.ID(), err)
+			return nil, fmt.Errorf("cannot create container graph for pod %s: %w", p.ID(), err)
 		}
 
 		removalErr = fmt.Errorf("creating container graph for pod %s failed, fell back to loop removal: %w", p.ID(), err)
 
-		if err := r.removeMalformedPod(ctx, p, ctrs, force, timeout, ctrNamedVolumes); err != nil {
+		removedCtrs, err = r.removeMalformedPod(ctx, p, ctrs, force, timeout, ctrNamedVolumes)
+		if err != nil {
 			logrus.Errorf("Error creating container graph for pod %s: %v. Falling back to loop removal.", p.ID(), err)
-			return err
+			return removedCtrs, err
 		}
 	} else {
 		ctrErrors := make(map[string]error)
@@ -223,16 +236,13 @@ func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool,
 			removeNode(ctx, node, p, force, timeout, false, ctrErrors, ctrsVisited, ctrNamedVolumes)
 		}
 
-		// This is gross, but I don't want to change the signature on
-		// removePod - especially since any change here eventually has
-		// to map down to one error unless we want to make a breaking
-		// API change.
+		// Finalize the removed containers list
+		for ctr, _ := range ctrsVisited {
+			removedCtrs[ctr] = ctrErrors[ctr]
+		}
+
 		if len(ctrErrors) > 0 {
-			var allErrs error
-			for id, err := range ctrErrors {
-				allErrs = multierror.Append(allErrs, fmt.Errorf("removing container %s from pod %s: %w", id, p.ID(), err))
-			}
-			return allErrs
+			return removedCtrs, fmt.Errorf("not all containers could be removed from pod %s: %w", p.ID(), define.ErrCtrExists)
 		}
 	}
 
@@ -319,7 +329,7 @@ func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool,
 	}
 
 	if err := p.maybeRemoveServiceContainer(); err != nil {
-		return err
+		return removedCtrs, err
 	}
 
 	// Remove pod from state
@@ -327,7 +337,7 @@ func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool,
 		if removalErr != nil {
 			logrus.Errorf("%v", removalErr)
 		}
-		return err
+		return removedCtrs, err
 	}
 
 	// Mark pod invalid
@@ -343,5 +353,5 @@ func (r *Runtime) removePod(ctx context.Context, p *Pod, removeCtrs, force bool,
 		}
 	}
 
-	return removalErr
+	return removedCtrs, removalErr
 }