feat: Add optional relationships column in table output

Add optional relationships column to display the relationships the
object has with its parent.

Users can view this optional column by simply including the `-o wide`
flag in the command.

Signed-off-by: Justin Toh <tohjustin@hotmail.com>

pkg/cmd/lineage/graph.go

@@ -1,17 +1,37 @@
 package lineage
 
 import (
+	"sort"
+
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	unstructuredv1 "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/klog/v2"
 )
 
-// NodeMap represents an owner-dependent relationship tree stored as a map of
-// nodes.
-type NodeMap map[types.UID]*Node
+type sortableStringSlice []string
+
+func (s sortableStringSlice) Len() int           { return len(s) }
+func (s sortableStringSlice) Less(i, j int) bool { return s[i] < s[j] }
+func (s sortableStringSlice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+
+// Relationship represents a relationship type.
+type Relationship string
+
+// RelationshipSet contains a set of relationships.
+type RelationshipSet map[Relationship]struct{}
+
+// List returns the contents as a sorted string slice.
+func (s RelationshipSet) List() []string {
+	res := make(sortableStringSlice, 0, len(s))
+	for key := range s {
+		res = append(res, string(key))
+	}
+	sort.Sort(res)
+	return []string(res)
+}
 
-// Node represents a Kubernetes object in an owner-dependent relationship tree.
+// Node represents a Kubernetes object in an relationship tree.
 type Node struct {
 	*unstructuredv1.Unstructured
 	UID             types.UID
@@ -20,11 +40,19 @@ type Node struct {
 	Group           string
 	Kind            string
 	OwnerReferences []metav1.OwnerReference
-	Dependents      []types.UID
+	Dependents      map[types.UID]RelationshipSet
 }
 
+// NodeMap contains a relationship tree stored as a map of nodes.
+type NodeMap map[types.UID]*Node
+
+const (
+	RelationshipOwnerRef Relationship = "OwnerReference"
+)
+
 // resolveDependents resolves all dependents of the provided root object and
-// returns an owner-dependent relationship tree.
+// returns a relationship tree.
+//nolint:funlen
 func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID) NodeMap {
 	// Create global node map of all objects
 	globalMap := NodeMap{}
@@ -33,6 +61,7 @@ func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID)
 			Unstructured:    &objects[ix],
 			UID:             o.GetUID(),
 			OwnerReferences: o.GetOwnerReferences(),
+			Dependents:      map[types.UID]RelationshipSet{},
 		}
 		globalMap[node.UID] = &node
 	}
@@ -42,7 +71,10 @@ func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID)
 		uid, ownerRefs := node.UID, node.OwnerReferences
 		for _, ref := range ownerRefs {
 			if owner, ok := globalMap[ref.UID]; ok {
-				owner.Dependents = append(owner.Dependents, uid)
+				if _, ok := owner.Dependents[uid]; !ok {
+					owner.Dependents[uid] = RelationshipSet{}
+				}
+				owner.Dependents[uid][RelationshipOwnerRef] = struct{}{}
 			}
 		}
 	}
@@ -68,10 +100,13 @@ func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID)
 		}
 
 		if node := nodeMap[uid]; node != nil {
-			for _, dUID := range node.Dependents {
+			dependents, ix := make([]types.UID, len(node.Dependents)), 0
+			for dUID := range node.Dependents {
 				nodeMap[dUID] = globalMap[dUID]
+				dependents[ix] = dUID
+				ix++
 			}
-			uidQueue = append(uidQueue[1:], node.Dependents...)
+			uidQueue = append(uidQueue[1:], dependents...)
 		}
 	}
 

pkg/cmd/lineage/printer_table.go

@@ -29,6 +29,7 @@ var (
 		{Name: "Ready", Type: "string", Description: "The readiness state of this object."},
 		{Name: "Status", Type: "string", Description: "The status of this object."},
 		{Name: "Age", Type: "string", Description: metav1.ObjectMeta{}.SwaggerDoc()["creationTimestamp"]},
+		{Name: "Relationships", Type: "array", Description: "The relationships this object has with its parent.", Priority: -1},
 	}
 	// objectReadyReasonJSONPath is the JSON path to get a Kubernetes object's
 	// "Ready" condition reason.
@@ -38,8 +39,7 @@ var (
 	objectReadyStatusJSONPath = newJSONPath("status", "{.status.conditions[?(@.type==\"Ready\")].status}")
 )
 
-// NodeList represents an owner-dependent relationship tree stored as flat list
-// of nodes.
+// NodeList contains a list of nodes.
 type NodeList []*Node
 
 func (n NodeList) Len() int {
@@ -275,8 +275,9 @@ func getStatefulSetReadyStatus(u *unstructuredv1.Unstructured) (string, string,
 
 // nodeToTableRow converts the provided node into a table row.
 //nolint:goconst
-func nodeToTableRow(node *Node, namePrefix string, showGroupFn func(kind string) bool) metav1.TableRow {
+func nodeToTableRow(node *Node, rset RelationshipSet, namePrefix string, showGroupFn func(kind string) bool) metav1.TableRow {
 	var name, ready, status, age string
+	var relationships interface{}
 
 	if showGroupFn(node.Kind) && len(node.Group) > 0 {
 		name = fmt.Sprintf("%s%s.%s/%s", namePrefix, node.Kind, node.Group, node.Name)
@@ -303,6 +304,11 @@ func nodeToTableRow(node *Node, namePrefix string, showGroupFn func(kind string)
 		ready = cellNotApplicable
 	}
 	age = translateTimestampSince(node.GetCreationTimestamp())
+	if r := rset.List(); len(r) > 0 {
+		relationships = r
+	} else {
+		relationships = cellNotApplicable
+	}
 
 	return metav1.TableRow{
 		Object: runtime.RawExtension{Object: node.DeepCopyObject()},
@@ -311,6 +317,7 @@ func nodeToTableRow(node *Node, namePrefix string, showGroupFn func(kind string)
 			ready,
 			status,
 			age,
+			relationships,
 		},
 	}
 }
@@ -335,23 +342,24 @@ func printNode(nodeMap NodeMap, root *Node, withGroup bool) ([]metav1.TableRow,
 	}
 	// Sorts the list of UIDs based on the underlying object in following order:
 	// Namespace, Kind, Group, Name
-	sortUIDsFn := func(uids []types.UID) []types.UID {
-		nodes := make(NodeList, len(uids))
-		for ix, uid := range uids {
+	sortDependentsFn := func(d map[types.UID]RelationshipSet) []types.UID {
+		nodes, ix := make(NodeList, len(d)), 0
+		for uid := range d {
 			nodes[ix] = nodeMap[uid]
+			ix++
 		}
 		sort.Sort(nodes)
-		sortedUIDs := make([]types.UID, len(uids))
+		sortedUIDs := make([]types.UID, len(d))
 		for ix, node := range nodes {
 			sortedUIDs[ix] = node.UID
 		}
 		return sortedUIDs
 	}
 
 	var rows []metav1.TableRow
-	row := nodeToTableRow(root, "", showGroupFn)
+	row := nodeToTableRow(root, nil, "", showGroupFn)
 	uidSet := map[types.UID]struct{}{}
-	dependentRows, err := printNodeDependents(nodeMap, uidSet, root, "", sortUIDsFn, showGroupFn)
+	dependentRows, err := printNodeDependents(nodeMap, uidSet, root, "", sortDependentsFn, showGroupFn)
 	if err != nil {
 		return nil, err
 	}
@@ -367,7 +375,7 @@ func printNodeDependents(
 	uidSet map[types.UID]struct{},
 	node *Node,
 	prefix string,
-	sortUIDsFn func(uids []types.UID) []types.UID,
+	sortDependentsFn func(d map[types.UID]RelationshipSet) []types.UID,
 	showGroupFn func(kind string) bool) ([]metav1.TableRow, error) {
 	rows := make([]metav1.TableRow, 0, len(nodeMap))
 
@@ -377,7 +385,7 @@ func printNodeDependents(
 	}
 	uidSet[node.UID] = struct{}{}
 
-	dependents := sortUIDsFn(node.Dependents)
+	dependents := sortDependentsFn(node.Dependents)
 	lastIx := len(dependents) - 1
 	for ix, childUID := range dependents {
 		var childPrefix, dependentPrefix string
@@ -391,8 +399,12 @@ func printNodeDependents(
 		if !ok {
 			return nil, fmt.Errorf("dependent object (uid: %s) not found in list of fetched objects", childUID)
 		}
-		row := nodeToTableRow(child, childPrefix, showGroupFn)
-		dependentRows, err := printNodeDependents(nodeMap, uidSet, child, dependentPrefix, sortUIDsFn, showGroupFn)
+		rset, ok := node.Dependents[childUID]
+		if !ok {
+			return nil, fmt.Errorf("dependent object (uid: %s) not found", childUID)
+		}
+		row := nodeToTableRow(child, rset, childPrefix, showGroupFn)
+		dependentRows, err := printNodeDependents(nodeMap, uidSet, child, dependentPrefix, sortDependentsFn, showGroupFn)
 		if err != nil {
 			return nil, err
 		}