[VOL-2312] Logging - Integrate voltctl with new etcd-based dynamic loglevel mechanism. Testing is in progress

Change-Id: I2e13bb79008c9a49ebb6f58e575f51efebe6dbfd
diff --git a/vendor/go.etcd.io/etcd/pkg/logutil/zap_journal.go b/vendor/go.etcd.io/etcd/pkg/logutil/zap_journal.go
new file mode 100644
index 0000000..fcd3903
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/pkg/logutil/zap_journal.go
@@ -0,0 +1,92 @@
+// Copyright 2018 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !windows
+
+package logutil
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"go.etcd.io/etcd/pkg/systemd"
+
+	"github.com/coreos/go-systemd/journal"
+	"go.uber.org/zap/zapcore"
+)
+
+// NewJournalWriter wraps "io.Writer" to redirect log output
+// to the local systemd journal. If journald send fails, it fails
+// back to writing to the original writer.
+// The decode overhead is only <30µs per write.
+// Reference: https://github.com/coreos/pkg/blob/master/capnslog/journald_formatter.go
+func NewJournalWriter(wr io.Writer) (io.Writer, error) {
+	return &journalWriter{Writer: wr}, systemd.DialJournal()
+}
+
+type journalWriter struct {
+	io.Writer
+}
+
+// WARN: assume that etcd uses default field names in zap encoder config
+// make sure to keep this up-to-date!
+type logLine struct {
+	Level  string `json:"level"`
+	Caller string `json:"caller"`
+}
+
+func (w *journalWriter) Write(p []byte) (int, error) {
+	line := &logLine{}
+	if err := json.NewDecoder(bytes.NewReader(p)).Decode(line); err != nil {
+		return 0, err
+	}
+
+	var pri journal.Priority
+	switch line.Level {
+	case zapcore.DebugLevel.String():
+		pri = journal.PriDebug
+	case zapcore.InfoLevel.String():
+		pri = journal.PriInfo
+
+	case zapcore.WarnLevel.String():
+		pri = journal.PriWarning
+	case zapcore.ErrorLevel.String():
+		pri = journal.PriErr
+
+	case zapcore.DPanicLevel.String():
+		pri = journal.PriCrit
+	case zapcore.PanicLevel.String():
+		pri = journal.PriCrit
+	case zapcore.FatalLevel.String():
+		pri = journal.PriCrit
+
+	default:
+		panic(fmt.Errorf("unknown log level: %q", line.Level))
+	}
+
+	err := journal.Send(string(p), pri, map[string]string{
+		"PACKAGE":           filepath.Dir(line.Caller),
+		"SYSLOG_IDENTIFIER": filepath.Base(os.Args[0]),
+	})
+	if err != nil {
+		// "journal" also falls back to stderr
+		// "fmt.Fprintln(os.Stderr, s)"
+		return w.Writer.Write(p)
+	}
+	return 0, nil
+}