From f36a0c13b0bc8aeb6c8b7e50ef6fbd7693fb1d9d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20R=C3=B6hl?= <Thomas.Roehl@googlemail.com>
Date: Tue, 19 Mar 2024 18:32:36 +0100
Subject: [PATCH] Sink to send metrics to Syslog

---
 sinks/syslogSink.go | 159 ++++++++++++++++++++++++++++++++++++++++++++
 sinks/syslogSink.md |  64 ++++++++++++++++++
 2 files changed, 223 insertions(+)
 create mode 100644 sinks/syslogSink.go
 create mode 100644 sinks/syslogSink.md

diff --git a/sinks/syslogSink.go b/sinks/syslogSink.go
new file mode 100644
index 0000000..b3f6aac
--- /dev/null
+++ b/sinks/syslogSink.go
@@ -0,0 +1,159 @@
+package sinks
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log/syslog"
+
+	cclog "github.com/ClusterCockpit/cc-metric-collector/pkg/ccLogger"
+	lp "github.com/ClusterCockpit/cc-metric-collector/pkg/ccMetric"
+)
+
+var AvailableSyslogPriorities map[string]syslog.Priority = map[string]syslog.Priority{
+	"LOG_EMERG":    syslog.LOG_EMERG,
+	"LOG_ALERT":    syslog.LOG_ALERT,
+	"LOG_CRIT":     syslog.LOG_CRIT,
+	"LOG_ERR":      syslog.LOG_ERR,
+	"LOG_NOTICE":   syslog.LOG_NOTICE,
+	"LOG_INFO":     syslog.LOG_INFO,
+	"LOG_DEBUG":    syslog.LOG_DEBUG,
+	"LOG_USER":     syslog.LOG_USER,
+	"LOG_MAIL":     syslog.LOG_MAIL,
+	"LOG_DAEMON":   syslog.LOG_DAEMON,
+	"LOG_AUTH":     syslog.LOG_AUTH,
+	"LOG_SYSLOG":   syslog.LOG_SYSLOG,
+	"LOG_LPR":      syslog.LOG_LPR,
+	"LOG_NEWS":     syslog.LOG_NEWS,
+	"LOG_UUCP":     syslog.LOG_UUCP,
+	"LOG_CRON":     syslog.LOG_CRON,
+	"LOG_AUTHPRIV": syslog.LOG_AUTHPRIV,
+	"LOG_FTP":      syslog.LOG_FTP,
+	"LOG_LOCAL0":   syslog.LOG_LOCAL0,
+	"LOG_LOCAL1":   syslog.LOG_LOCAL1,
+	"LOG_LOCAL2":   syslog.LOG_LOCAL2,
+	"LOG_LOCAL3":   syslog.LOG_LOCAL3,
+	"LOG_LOCAL4":   syslog.LOG_LOCAL4,
+	"LOG_LOCAL5":   syslog.LOG_LOCAL5,
+	"LOG_LOCAL6":   syslog.LOG_LOCAL6,
+	"LOG_LOCAL7":   syslog.LOG_LOCAL7,
+}
+
+type SyslogSinkConfig struct {
+	defaultSinkConfig
+	SyslogTag      string   `json:"syslog_tag"`
+	SyslogPriories []string `json:"syslog_priorities"`
+	SyslogWriter   string   `json:"syslog_writer"`
+}
+
+type SyslogSink struct {
+	sink
+	config      SyslogSinkConfig // entry point to the SyslogSinkConfig
+	syslogPrios syslog.Priority
+	out         *syslog.Writer
+}
+
+func (s *SyslogSink) Write(point lp.CCMetric) error {
+	var err error = nil
+	p := point.ToLineProtocol(s.meta_as_tags)
+	switch s.config.SyslogWriter {
+	case "info":
+		err = s.out.Info(p)
+	case "debug":
+		err = s.out.Debug(p)
+	case "alert":
+		err = s.out.Alert(p)
+	case "emerg":
+		err = s.out.Emerg(p)
+	case "err":
+		err = s.out.Err(p)
+	case "notice":
+		err = s.out.Notice(p)
+	case "warning":
+		err = s.out.Warning(p)
+	}
+
+	return err
+}
+
+func (s *SyslogSink) Flush() error {
+	return nil
+}
+
+func (s *SyslogSink) Close() {
+	s.out.Close()
+	cclog.ComponentDebug(s.name, "CLOSE")
+}
+
+func NewSyslogSink(name string, config json.RawMessage) (Sink, error) {
+	var err error = nil
+	s := new(SyslogSink)
+
+	s.name = fmt.Sprintf("SyslogSink(%s)", name)
+
+	// Read in the config JSON
+	if len(config) > 0 {
+		d := json.NewDecoder(bytes.NewReader(config))
+		d.DisallowUnknownFields()
+		if err := d.Decode(&s.config); err != nil {
+			cclog.ComponentError(s.name, "Error reading config:", err.Error())
+			return nil, err
+		}
+	}
+
+	// Create lookup map to use meta infos as tags in the output metric
+	s.meta_as_tags = make(map[string]bool)
+	for _, k := range s.config.MetaAsTags {
+		s.meta_as_tags[k] = true
+	}
+
+	if len(s.config.SyslogTag) == 0 {
+		err := errors.New("syslog tag must be non-empty")
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+
+	if len(s.config.SyslogPriories) == 0 {
+		err := errors.New("syslog prioritiey must be non-empty")
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+	for _, p := range s.config.SyslogPriories {
+		if prio, ok := AvailableSyslogPriorities[p]; !ok {
+			err := fmt.Errorf("invalid syslog priority '%s'", p)
+			cclog.ComponentError(s.name, err.Error())
+			return nil, err
+		} else {
+			s.syslogPrios |= prio
+		}
+	}
+
+	mywriter := ""
+	for _, w := range []string{
+		"info",
+		"debug",
+		"alert",
+		"emerg",
+		"err",
+		"notice",
+		"warning",
+	} {
+		if s.config.SyslogWriter == w {
+			mywriter = w
+		}
+	}
+	if len(mywriter) == 0 {
+		err := fmt.Errorf("invalid syslog writer '%s'", s.config.SyslogWriter)
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+
+	s.out, err = syslog.New(s.syslogPrios, s.config.SyslogTag)
+	if err != nil {
+		cclog.ComponentError(s.name, err.Error())
+		return nil, err
+	}
+
+	return s, nil
+}
diff --git a/sinks/syslogSink.md b/sinks/syslogSink.md
new file mode 100644
index 0000000..506ceba
--- /dev/null
+++ b/sinks/syslogSink.md
@@ -0,0 +1,64 @@
+## `syslog` sink
+
+The `syslog` sink provides an easy way to submit metrics and events to the Syslog logging system.
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "syslog",
+    "meta_as_tags" : [],
+    "syslog_tag" : "mytag",
+    "syslog_priorities" : [
+        "LOG_INFO",
+        "LOG_LOCAL7",
+    ],
+    "syslog_writer" : "info"
+  }
+}
+```
+
+- `type`: makes the sink an `syslog` sink
+- `meta_as_tags`: print meta information as tags in the output (optional)
+- `syslog_tag`: The tag submitted with each message
+- `syslog_priorities`: List of syslog priorities. Will be OR'd together
+- `syslog_writer`: Submit metrics with this write level
+
+
+#### Possible priorities for `syslog_priorities`
+- `LOG_EMERG`
+- `LOG_ALERT`
+- `LOG_CRIT`
+- `LOG_ERR`
+- `LOG_NOTICE`
+- `LOG_INFO`
+- `LOG_DEBUG`
+- `LOG_USER`
+- `LOG_MAIL`
+- `LOG_DAEMON`
+- `LOG_AUTH`
+- `LOG_SYSLOG`
+- `LOG_LPR`
+- `LOG_NEWS`
+- `LOG_UUCP`
+- `LOG_CRON`
+- `LOG_AUTHPRIV`
+- `LOG_FTP`
+- `LOG_LOCAL0`
+- `LOG_LOCAL1`
+- `LOG_LOCAL2`
+- `LOG_LOCAL3`
+- `LOG_LOCAL4`
+- `LOG_LOCAL5`
+- `LOG_LOCAL6`
+- `LOG_LOCAL7`
+
+#### Possible writers for `syslog_writer`
+- `info`
+- `debug`
+- `alert`
+- `emerg`
+- `err`
+- `notice`
+- `warning`
\ No newline at end of file