Backend plugins: Log wrapper args formatting (#20514)

Backend plugins is recommended to use hclog with json 
formatting to get proper log output in grafana server log.
Old hclog-wrapper.go that I deleted while back is still in 
the repo so deletes that.

pkg/plugins/backendplugin/log_wrapper.go

@@ -13,20 +13,41 @@ type logWrapper struct {
 	Logger glog.Logger
 }
 
+func formatArgs(args ...interface{}) []interface{} {
+	if len(args) == 0 || len(args)%2 != 0 {
+		return args
+	}
+
+	res := []interface{}{}
+
+	for n := 0; n < len(args); n = n + 2 {
+		key := args[n]
+
+		if stringKey, ok := key.(string); ok && stringKey == "timestamp" {
+			continue
+		}
+
+		res = append(res, key)
+		res = append(res, args[n+1])
+	}
+
+	return res
+}
+
 func (lw logWrapper) Trace(msg string, args ...interface{}) {
-	lw.Logger.Debug(msg, args...)
+	lw.Logger.Debug(msg, formatArgs(args...)...)
 }
 func (lw logWrapper) Debug(msg string, args ...interface{}) {
-	lw.Logger.Debug(msg, args...)
+	lw.Logger.Debug(msg, formatArgs(args...)...)
 }
 func (lw logWrapper) Info(msg string, args ...interface{}) {
-	lw.Logger.Info(msg, args...)
+	lw.Logger.Info(msg, formatArgs(args...)...)
 }
 func (lw logWrapper) Warn(msg string, args ...interface{}) {
-	lw.Logger.Warn(msg, args...)
+	lw.Logger.Warn(msg, formatArgs(args...)...)
 }
 func (lw logWrapper) Error(msg string, args ...interface{}) {
-	lw.Logger.Error(msg, args...)
+	lw.Logger.Error(msg, formatArgs(args...)...)
 }
 
 func (lw logWrapper) IsTrace() bool { return true }

pkg/plugins/backendplugin/log_wrapper_test.go

@@ -0,0 +1,29 @@
+package backendplugin
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLogWrapper(t *testing.T) {
+	tcs := []struct {
+		args           []interface{}
+		expectedResult []interface{}
+	}{
+		{args: []interface{}{}, expectedResult: []interface{}{}},
+		{args: []interface{}{"1", "2", "3"}, expectedResult: []interface{}{"1", "2", "3"}},
+		{args: []interface{}{"1", "2"}, expectedResult: []interface{}{"1", "2"}},
+		{args: []interface{}{"1", "2", "timestamp", time.Now()}, expectedResult: []interface{}{"1", "2"}},
+		{args: []interface{}{"1", "2", "timestamp", time.Now(), "3", "4"}, expectedResult: []interface{}{"1", "2", "3", "4"}},
+	}
+
+	for i, tc := range tcs {
+		t.Run(fmt.Sprintf("formatArgs testcase %d", i), func(t *testing.T) {
+			res := formatArgs(tc.args...)
+			assert.Exactly(t, tc.expectedResult, res)
+		})
+	}
+}