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)
+}

internal/pkg/node/hash_test.go

@@ -0,0 +1,111 @@
+package node
+
+import (
+	"fmt"
+	"testing"
+
+	"gopkg.in/yaml.v2"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHash(t *testing.T) {
+	nodeConfYml1 := `
+WW_INTERNAL: 43
+nodeprofiles:
+  default:
+    comment: This profile is automatically included for each node
+  test:
+    comment: This is a test profile
+nodes:
+  n01:
+    discoverable: true
+    profiles:
+    - default
+    network devices:
+      default:
+        ipaddr: 10.0.10.1
+  n02:
+    discoverable: true
+    profiles:
+    - default
+    network devices:
+      testnet:
+        ipaddr: 10.0.10.2
+`
+	nodeConfYml2 := `
+WW_INTERNAL: 43
+nodeprofiles:
+  default:
+    comment: This profile is automatically included for each node
+  test:
+    comment: This is a test profile
+nodes:
+  n02:
+    discoverable: true
+    profiles:
+    - default
+    network devices:
+      default:
+        ipaddr: 10.0.10.2
+  n01:
+    discoverable: true
+    profiles:
+    - default
+    network devices:
+      default:
+        ipaddr: 10.0.10.1
+`
+	nodeConfYml3 := `
+WW_INTERNAL: 43
+nodeprofiles:
+  default:
+    comment: This profile is automatically included for each node
+  test:
+    comment: This is a test profile
+nodes:
+  n02:
+    discoverable: true
+    profiles:
+    - default
+    network devices:
+      default:
+        ipaddr: 10.0.10.2
+  n01:
+    discoverable: true
+    profiles:
+    - default
+    network devices:
+      default:
+        ipaddr: 10.0.10.3
+`
+	var nodeConf1, nodeConf2, nodeConf3 NodeYaml
+	err := yaml.Unmarshal([]byte(nodeConfYml1), &nodeConf1)
+	fmt.Println(nodeConf1.Nodes["n01"])
+	assert.NoError(t, err)
+	err = yaml.Unmarshal([]byte(nodeConfYml2), &nodeConf2)
+	assert.NoError(t, err)
+	err = yaml.Unmarshal([]byte(nodeConfYml3), &nodeConf3)
+	assert.NoError(t, err)
+
+	t.Run("Same NodeYaml with same conf", func(t *testing.T) {
+		var testConf NodeYaml
+		yaml.Unmarshal([]byte(nodeConfYml1), &testConf)
+		if testConf.Hash() != nodeConf1.Hash() {
+			yaml.Unmarshal([]byte(nodeConfYml1), nodeConf1)
+			t.Errorf("Hashes for same configuration differs: %x != %x", nodeConf1.Hash(), nodeConf1.Hash())
+		}
+	})
+
+	t.Run("Different sorted NodeYaml with same conf", func(t *testing.T) {
+		if nodeConf2.Hash() != nodeConf1.Hash() {
+			t.Errorf("Hashes for same configuration differs: %x != %x", nodeConf2.Hash(), nodeConf1.Hash())
+		}
+	})
+
+	t.Run("Different NodeYaml with different conf", func(t *testing.T) {
+		if nodeConf2.Hash() == nodeConf3.Hash() {
+			t.Errorf("Hashes for different configuration is the same: %x == %x", nodeConf2.Hash(), nodeConf3.Hash())
+		}
+	})
+}