Use Node literal in MergeNode, not EmptyNode()

EmptyNode populates empty sub-structs, which interferes with omitempty during
serialization.

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/pkg/api/node/list.go

@@ -76,9 +76,13 @@ func NodeList(nodeGet *wwapiv1.GetNodeList) (nodeList wwapiv1.NodeList, err erro
 		nodeList.Output = append(nodeList.Output,
 			fmt.Sprintf("%s:=:%s:=:%s:=:%s", "NODE NAME", "KERNEL VERSION", "CONTAINER", "OVERLAYS (S/R)"))
 		for _, n := range node.FilterNodeListByName(nodes, nodeGet.Nodes) {
+			kernelVersion := ""
+			if n.Kernel != nil {
+				kernelVersion = n.Kernel.Version
+			}
 			nodeList.Output = append(nodeList.Output,
 				fmt.Sprintf("%s:=:%s:=:%s:=:%s", n.Id(),
-					n.Kernel.Version,
+					kernelVersion,
 					n.ContainerName,
 					strings.Join(n.SystemOverlay, ",")+"/"+strings.Join(n.RuntimeOverlay, ",")))
 		}

internal/pkg/kernel/kernel.go

@@ -75,7 +75,7 @@ func FromNode(node *node.Node) *Kernel {
 	wwlog.Debug("FromNode(%v)", node)
 	if node.ContainerName == "" {
 		return nil
-	} else if node.Kernel.Version != "" {
+	} else if node.Kernel != nil && node.Kernel.Version != "" {
 		kernel := &Kernel{ContainerName: node.ContainerName, Path: filepath.Join("/", node.Kernel.Version)}
 		if util.IsFile(kernel.FullPath()) {
 			return kernel

internal/pkg/node/mergo.go

@@ -113,7 +113,7 @@ func (config *NodesYaml) MergeNode(id string) (node Node, fields fieldMap, err e
 		return node, fields, err
 	}
 	originalNode := node
-	node = EmptyNode()
+	node = Node{}
 
 	fields = make(fieldMap)
 

internal/pkg/node/mergo_test.go

@@ -822,3 +822,119 @@ nodes:
 		})
 	}
 }
+
+func Test_MergeNodeKernel(t *testing.T) {
+	var tests = map[string]struct {
+		nodesConf string
+		node      string
+		kernel    *KernelConf
+	}{
+		"interference": {
+			nodesConf: `
+nodeprofiles:
+  default: {}
+nodes:
+  node1: {}
+  test:
+    profiles:
+      - default
+    kernel:
+      version: v1.0.0
+      args: kernel-args`,
+			node:   "node1",
+			kernel: nil,
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			env := testenv.New(t)
+			defer env.RemoveAll()
+			env.WriteFile("/etc/warewulf/nodes.conf", tt.nodesConf)
+
+			registry, regErr := New()
+			assert.NoError(t, regErr)
+			node, _, mergeErr := registry.MergeNode(tt.node)
+			assert.NoError(t, mergeErr)
+			assert.Equal(t, tt.kernel, node.Kernel)
+		})
+	}
+}
+
+func Test_MergeNodeIpmi(t *testing.T) {
+	var tests = map[string]struct {
+		nodesConf string
+		node      string
+		ipmi      *IpmiConf
+	}{
+		"empty single node": {
+			nodesConf: `
+nodes:
+  n1: {}`,
+			node: "n1",
+			ipmi: nil,
+		},
+		"empty node among multiple": {
+			nodesConf: `
+nodes:
+  n0: {}
+  n1: {}
+  n2: {}`,
+			node: "n1",
+			ipmi: nil,
+		},
+		"populated node among multiple": {
+			nodesConf: `
+nodes:
+  n0: {}
+  n1:
+    ipmi:
+      username: root
+      password: passw0rd
+  n2: {}`,
+			node: "n1",
+			ipmi: &IpmiConf{
+				UserName: "root",
+				Password: "passw0rd",
+			},
+		},
+		"no previous interference": {
+			nodesConf: `
+nodes:
+  n0: {}
+  n1:
+    ipmi:
+      username: root
+      password: passw0rd
+  n2: {}`,
+			node: "n0",
+			ipmi: nil,
+		},
+		"no later interference": {
+			nodesConf: `
+nodes:
+  n0: {}
+  n1:
+    ipmi:
+      username: root
+      password: passw0rd
+  n2: {}`,
+			node: "n2",
+			ipmi: nil,
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			env := testenv.New(t)
+			defer env.RemoveAll()
+			env.WriteFile("/etc/warewulf/nodes.conf", tt.nodesConf)
+
+			registry, regErr := New()
+			assert.NoError(t, regErr)
+			node, _, mergeErr := registry.MergeNode(tt.node)
+			assert.NoError(t, mergeErr)
+			assert.Equal(t, tt.ipmi, node.Ipmi)
+		})
+	}
+}

internal/pkg/warewulfd/provision.go

@@ -174,6 +174,12 @@ func ProvisionSend(w http.ResponseWriter, req *http.Request) {
 			}
 		case "grub.cfg":
 			stage_file = path.Join(conf.Paths.Sysconfdir, "warewulf/grub/grub.cfg.ww")
+			kernelArgs := ""
+			kernelVersion := ""
+			if remoteNode.Kernel != nil {
+				kernelArgs = remoteNode.Kernel.Args
+				kernelVersion = remoteNode.Kernel.Version
+			}
 			tmpl_data = &templateVars{
 				Id:            remoteNode.Id(),
 				Cluster:       remoteNode.ClusterName,
@@ -183,8 +189,8 @@ func ProvisionSend(w http.ResponseWriter, req *http.Request) {
 				Hostname:      remoteNode.Id(),
 				Hwaddr:        rinfo.hwaddr,
 				ContainerName: remoteNode.ContainerName,
-				KernelArgs:    remoteNode.Kernel.Args,
-				KernelVersion: remoteNode.Kernel.Version,
+				KernelArgs:    kernelArgs,
+				KernelVersion: kernelVersion,
 				NetDevs:       remoteNode.NetDevs,
 				Tags:          remoteNode.Tags}
 			if stage_file == "" {