Merge pull request #8955 from mheon/rename

Container Rename

libpod/runtime_ctr.go

@@ -72,6 +72,140 @@ func (r *Runtime) RestoreContainer(ctx context.Context, rSpec *spec.Spec, config
 	return r.setupContainer(ctx, ctr)
 }
 
+// RenameContainer renames the given container.
+// The given container object will be rendered unusable, and a new, renamed
+// Container will be returned.
+func (r *Runtime) RenameContainer(ctx context.Context, ctr *Container, newName string) (*Container, error) {
+	ctr.lock.Lock()
+	defer ctr.lock.Unlock()
+
+	if err := ctr.syncContainer(); err != nil {
+		return nil, err
+	}
+
+	if newName == "" || !define.NameRegex.MatchString(newName) {
+		return nil, define.RegexError
+	}
+
+	// Check if the name is available.
+	// This is *100% NOT ATOMIC* so any failures in-flight will do
+	// *VERY BAD THINGS* to the state. So we have to try and catch all we
+	// can before starting.
+	if _, err := r.state.LookupContainerID(newName); err == nil {
+		return nil, errors.Wrapf(define.ErrCtrExists, "name %s is already in use by another container", newName)
+	}
+	if _, err := r.state.LookupPod(newName); err == nil {
+		return nil, errors.Wrapf(define.ErrPodExists, "name %s is already in use by another pod", newName)
+	}
+
+	// TODO: Investigate if it is possible to remove this limitation.
+	depCtrs, err := r.state.ContainerInUse(ctr)
+	if err != nil {
+		return nil, err
+	}
+	if len(depCtrs) > 0 {
+		return nil, errors.Wrapf(define.ErrCtrExists, "cannot rename container %s as it is in use by other containers: %v", ctr.ID(), strings.Join(depCtrs, ","))
+	}
+
+	// We need to pull an updated config, in case another rename fired and
+	// the config was re-written.
+	newConf, err := r.state.GetContainerConfig(ctr.ID())
+	if err != nil {
+		return nil, errors.Wrapf(err, "error retrieving container %s configuration from DB to remove", ctr.ID())
+	}
+	ctr.config = newConf
+
+	// TODO: This is going to fail if we have active exec sessions, too.
+	// Investigate fixing that at a later date.
+
+	var pod *Pod
+	if ctr.config.Pod != "" {
+		tmpPod, err := r.state.Pod(ctr.config.Pod)
+		if err != nil {
+			return nil, errors.Wrapf(err, "error retrieving container %s pod", ctr.ID())
+		}
+		pod = tmpPod
+		// Lock pod to ensure it's not removed while we're working
+		pod.lock.Lock()
+		defer pod.lock.Unlock()
+	}
+
+	// Lock all volumes to ensure they are not removed while we're working
+	volsLocked := make(map[string]bool)
+	for _, namedVol := range ctr.config.NamedVolumes {
+		if volsLocked[namedVol.Name] {
+			continue
+		}
+		vol, err := r.state.Volume(namedVol.Name)
+		if err != nil {
+			return nil, errors.Wrapf(err, "error retrieving volume used by container %s", ctr.ID())
+		}
+
+		volsLocked[vol.Name()] = true
+		vol.lock.Lock()
+		defer vol.lock.Unlock()
+	}
+
+	logrus.Infof("Going to rename container %s from %q to %q", ctr.ID(), ctr.Name(), newName)
+
+	// Step 1: remove the old container.
+	if pod != nil {
+		if err := r.state.RemoveContainerFromPod(pod, ctr); err != nil {
+			return nil, errors.Wrapf(err, "error renaming container %s", ctr.ID())
+		}
+	} else {
+		if err := r.state.RemoveContainer(ctr); err != nil {
+			return nil, errors.Wrapf(err, "error renaming container %s", ctr.ID())
+		}
+	}
+
+	// Step 2: Make a new container based on the old one.
+	// TODO: Should we deep-copy the container config and state, to be safe?
+	newCtr := new(Container)
+	newCtr.config = ctr.config
+	newCtr.state = ctr.state
+	newCtr.lock = ctr.lock
+	newCtr.ociRuntime = ctr.ociRuntime
+	newCtr.runtime = r
+	newCtr.rootlessSlirpSyncR = ctr.rootlessSlirpSyncR
+	newCtr.rootlessSlirpSyncW = ctr.rootlessSlirpSyncW
+	newCtr.rootlessPortSyncR = ctr.rootlessPortSyncR
+	newCtr.rootlessPortSyncW = ctr.rootlessPortSyncW
+
+	newCtr.valid = true
+	newCtr.config.Name = newName
+
+	// Step 3: Add that new container to the DB
+	if pod != nil {
+		if err := r.state.AddContainerToPod(pod, newCtr); err != nil {
+			return nil, errors.Wrapf(err, "error renaming container %s", newCtr.ID())
+		}
+	} else {
+		if err := r.state.AddContainer(newCtr); err != nil {
+			return nil, errors.Wrapf(err, "error renaming container %s", newCtr.ID())
+		}
+	}
+
+	// Step 4: Save the new container, to force the state to be written to
+	// the DB. This may not be necessary, depending on DB implementation,
+	// but let's do it to be safe.
+	if err := newCtr.save(); err != nil {
+		return nil, err
+	}
+
+	// Step 5: rename the container in c/storage.
+	// This can fail if the name is already in use by a non-Podman
+	// container. This puts us in a bad spot - we've already renamed the
+	// container in Podman. We can swap the order, but then we have the
+	// opposite problem. Atomicity is a real problem here, with no easy
+	// solution.
+	if err := r.store.SetNames(newCtr.ID(), []string{newCtr.Name()}); err != nil {
+		return nil, err
+	}
+
+	return newCtr, nil
+}
+
 func (r *Runtime) initContainerVariables(rSpec *spec.Spec, config *ContainerConfig) (*Container, error) {
 	if rSpec == nil {
 		return nil, errors.Wrapf(define.ErrInvalidArg, "must provide a valid runtime spec to create container")
@@ -393,7 +527,7 @@ func (r *Runtime) RemoveContainer(ctx context.Context, c *Container, force bool,
 // removePod is used only when removing pods. It instructs Podman to ignore
 // infra container protections, and *not* remove from the database (as pod
 // remove will handle that).
-func (r *Runtime) removeContainer(ctx context.Context, c *Container, force bool, removeVolume bool, removePod bool) error {
+func (r *Runtime) removeContainer(ctx context.Context, c *Container, force, removeVolume, removePod bool) error {
 	span, _ := opentracing.StartSpanFromContext(ctx, "removeContainer")
 	span.SetTag("type", "runtime")
 	defer span.Finish()
@@ -406,6 +540,18 @@ func (r *Runtime) removeContainer(ctx context.Context, c *Container, force bool,
 		}
 	}
 
+	// We need to refresh container config from the DB, to ensure that any
+	// changes (e.g. a rename) are picked up before we start removing.
+	// Since HasContainer above succeeded, we can safely assume the
+	// container exists.
+	// This is *very iffy* but it should be OK because the container won't
+	// exist once we're done.
+	newConf, err := r.state.GetContainerConfig(c.ID())
+	if err != nil {
+		return errors.Wrapf(err, "error retrieving container %s configuration from DB to remove", c.ID())
+	}
+	c.config = newConf
+
 	logrus.Debugf("Removing container %s", c.ID())
 
 	// We need to lock the pod before we lock the container.
@@ -413,7 +559,6 @@ func (r *Runtime) removeContainer(ctx context.Context, c *Container, force bool,
 	// Don't need to do this in pod removal case - we're evicting the entire
 	// pod.
 	var pod *Pod
-	var err error
 	runtime := c.runtime
 	if c.config.Pod != "" && !removePod {
 		pod, err = r.state.Pod(c.config.Pod)