add hash function

Signed-off-by: Christian Goll <cgoll@suse.de>

internal/pkg/node/hash.go

@@ -0,0 +1,26 @@
+package node
+
+import (
+	"crypto/sha256"
+
+	"github.com/hpcng/warewulf/internal/pkg/wwlog"
+	"gopkg.in/yaml.v2"
+)
+
+/*
+Calculate the hash of NodeYaml in an orderder fashion
+*/
+func (config *NodeYaml) Hash() [32]byte {
+	// flatten out profiles and nodes
+	for _, val := range config.NodeProfiles {
+		val.Flatten()
+	}
+	for _, val := range config.Nodes {
+		val.Flatten()
+	}
+	data, err := yaml.Marshal(config)
+	if err != nil {
+		wwlog.Warn("couldn't marshall NodeYaml for hashing")
+	}
+	return sha256.Sum256(data)
+}