From dcdc911bd3f27d98bf5617b9fdd8849b1bad4b42 Mon Sep 17 00:00:00 2001
From: Jon Stevens <latchkey@gmail.com>
Date: Tue, 20 Mar 2018 14:48:11 +0700
Subject: [PATCH] recursively merge json objects instead of just merging keys

---
 service/agent/config_test.go | 47 ++++++++++++++++++++++++++++++++++++
 tool/json.go                 | 40 ++++++++++++++++++++++++++----
 2 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/service/agent/config_test.go b/service/agent/config_test.go
index 507e547..c17e0f2 100644
--- a/service/agent/config_test.go
+++ b/service/agent/config_test.go
@@ -23,6 +23,26 @@ const priorConfigVersion = `{
 }
 `
 
+const failingConfig = `
+{
+  "cmdLine": {
+    "port": ":1111"
+  },
+  "controller": {
+    "reboot": {
+      "delay": "5s"
+    }
+  },
+  "monitor": {
+    "load": {
+      "period_secs": 60,
+      "high_load_Mark": 5,
+      "enabled": true
+    }
+  }
+}
+`
+
 func defaultConfig() []byte {
 	data, _ := ioutil.ReadFile("../../conf/bam_agent.json")
 	return data
@@ -72,6 +92,33 @@ func TestNewConfig(t *testing.T) {
 	}
 }
 
+func TestLoadingOldConfig(t *testing.T) {
+	file, err := ioutil.TempFile("", "agent-config")
+	defer os.Remove(file.Name())
+
+	// Write out an old version of a file
+	ioutil.WriteFile(file.Name(), []byte(failingConfig), 644)
+	file.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cfg := NewConfig(tool.CmdLine{
+		AgentConfigPath: file.Name(),
+	}, defaultConfig())
+
+	if !cfg.Loaded().Monitor.HighLoad.Enabled {
+		t.Fatalf("expected highLoad to be enabled")
+	}
+
+	// We should have saved the file as part of the load
+	fileData, err := ioutil.ReadFile(file.Name())
+	if !strings.Contains(string(fileData), "highLoad") {
+		t.Fatalf("expected file data to have updated port number")
+	}
+}
+
 // simulate a BAM agent binary update that adds a structure to the default BAM interface
 // by saving a previous config file that doesnt have the current monitors in it
 func TestStructChangeToConfig(t *testing.T) {
diff --git a/tool/json.go b/tool/json.go
index df799af..6b6b2fe 100644
--- a/tool/json.go
+++ b/tool/json.go
@@ -89,17 +89,47 @@ func getRandomizedDuration(duration time.Duration) time.Duration {
 }
 
 /*
-	Merges source into/over destination
+	Recursively merges source into/over destination
 */
 func Merge(src []byte, dst []byte) ([]byte, error) {
-	var mergeMap map[string]interface{}
-	err := jsoniter.Unmarshal(dst, &mergeMap)
+	var err error
+
+	var srcObj interface{}
+	err = jsoniter.Unmarshal(src, &srcObj)
 	if err != nil {
 		return nil, err
 	}
-	err = jsoniter.Unmarshal(src, &mergeMap)
+
+	var dstObj interface{}
+	err = jsoniter.Unmarshal(dst, &dstObj)
 	if err != nil {
 		return nil, err
 	}
-	return jsoniter.Marshal(mergeMap)
+
+	return jsoniter.Marshal(merge1(srcObj, dstObj))
+}
+
+// https://play.golang.org/p/8jlJUbEJKf
+func merge1(x1, x2 interface{}) interface{} {
+	switch x1 := x1.(type) {
+	case map[string]interface{}:
+		x2, ok := x2.(map[string]interface{})
+		if !ok {
+			return x1
+		}
+		for k, v2 := range x2 {
+			if v1, ok := x1[k]; ok {
+				x1[k] = merge1(v1, v2)
+			} else {
+				x1[k] = v2
+			}
+		}
+	case nil:
+		// merge(nil, map[string]interface{...}) -> map[string]interface{...}
+		x2, ok := x2.(map[string]interface{})
+		if ok {
+			return x2
+		}
+	}
+	return x1
 }