Unconditionally retrieve pod names via API

The ListContainers API previously had a Pod parameter, which
determined if pod name was returned (but, notably, not Pod ID,
which was returned unconditionally). This was fairly confusing,
so we decided to deprecate/remove the parameter and return it
unconditionally.

To do this without serious performance implications, we need to
avoid expensive JSON decodes of pod configuration in the DB. The
way our Bolt tables are structured, retrieving name given ID is
actually quite cheap, but we did not expose this via the Libpod
API. Add a new GetName API to do this.

Fixes #7214

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

1 files changed, 55 insertions, 0 deletions

diff --git a/libpod/boltdb_state.go b/libpod/boltdb_state.go
index 2575f0e86..9dd5ca465 100644
--- a/libpod/boltdb_state.go
+++ b/libpod/boltdb_state.go
@@ -424,6 +424,61 @@ func (s *BoltState) SetNamespace(ns string) error {
 	return nil
 }
 
+// GetName returns the name associated with a given ID. Since IDs are globally
+// unique, it works for both containers and pods.
+// Returns ErrNoSuchCtr if the ID does not exist.
+func (s *BoltState) GetName(id string) (string, error) {
+	if id == "" {
+		return "", define.ErrEmptyID
+	}
+
+	if !s.valid {
+		return "", define.ErrDBClosed
+	}
+
+	idBytes := []byte(id)
+
+	db, err := s.getDBCon()
+	if err != nil {
+		return "", err
+	}
+	defer s.deferredCloseDBCon(db)
+
+	name := ""
+
+	err = db.View(func(tx *bolt.Tx) error {
+		idBkt, err := getIDBucket(tx)
+		if err != nil {
+			return err
+		}
+
+		nameBytes := idBkt.Get(idBytes)
+		if nameBytes == nil {
+			return define.ErrNoSuchCtr
+		}
+
+		if s.namespaceBytes != nil {
+			nsBkt, err := getNSBucket(tx)
+			if err != nil {
+				return err
+			}
+
+			idNs := nsBkt.Get(idBytes)
+			if !bytes.Equal(idNs, s.namespaceBytes) {
+				return define.ErrNoSuchCtr
+			}
+		}
+
+		name = string(nameBytes)
+		return nil
+	})
+	if err != nil {
+		return "", err
+	}
+
+	return name, nil
+}
+
 // Container retrieves a single container from the state by its full ID
 func (s *BoltState) Container(id string) (*Container, error) {
 	if id == "" {