Usage example of go-syslog to parse a stream of syslog messages with octet-counting framing

go-syslog-octet-couting-stream.go

package main

import (
  "io"
  "time"

  "github.com/davecgh/go-spew/spew"
  syslog "github.com/influxdata/go-syslog/v2"
  "github.com/influxdata/go-syslog/v2/octetcounting"
)

func main() {
  // Messages containing MSGLEN token at their start
  messages := []string{
    "16 <1>1 - - - - - -",
    "17 <2>12 A B C D E -",
    "16 <1>1",
  }

  r, w := io.Pipe()

  // Goroutine sending one syslog messages per second in the tube ..
  go func() {
    defer w.Close()
    for _, m := range messages {
      w.Write([]byte(m))
      time.Sleep(time.Second)
    }
  }()

  // Custom listener pushing parsing results on a channel
  // Register them using syslog.WithListener
  c := make(chan syslog.Result)
  emit := func(res *syslog.Result) {
    c <- *res
  }

  // Parser taking generic options (best effort and custom listener)
  parser := octetcounting.NewParser(syslog.WithBestEffort(), syslog.WithListener(emit))
  
  // Goroutine that parses syslog messages as it receives them
  go func() {
    defer close(c)
    parser.Parse(r)
  }()

  // Printing out syslog.Message instances
  for r := range c {
    spew.Dump(r)
  }

  r.Close()
}

// (syslog.Result) {
//  Message: (*rfc5424.SyslogMessage)(0xc0000a2060)({
//   priority: (*uint8)(0xc0000a6003)(1),
//   facility: (*uint8)(0xc0000a6004)(0),
//   severity: (*uint8)(0xc0000a6005)(1),
//   version: (uint16) 1,
//   timestamp: (*time.Time)(<nil>),
//   hostname: (*string)(<nil>),
//   appname: (*string)(<nil>),
//   procID: (*string)(<nil>),
//   msgID: (*string)(<nil>),
//   structuredData: (*map[string]map[string]string)(<nil>),
//   message: (*string)(<nil>)
//  }),
//  Error: (error) <nil>
// }
// (syslog.Result) {
//  Message: (*rfc5424.SyslogMessage)(0xc0000a2120)({
//   priority: (*uint8)(0xc0000a6230)(2),
//   facility: (*uint8)(0xc0000a6231)(0),
//   severity: (*uint8)(0xc0000a6232)(2),
//   version: (uint16) 12,
//   timestamp: (*time.Time)(<nil>),
//   hostname: (*string)(<nil>),
//   appname: (*string)(<nil>),
//   procID: (*string)(<nil>),
//   msgID: (*string)(<nil>),
//   structuredData: (*map[string]map[string]string)(<nil>),
//   message: (*string)(<nil>)
//  }),
//  Error: (*errors.errorString)(0xc0000b0050)(expecting a RFC3339MICRO timestamp or a nil value [col 6])
// }
// (syslog.Result) {
//  Message: (*rfc5424.SyslogMessage)(0xc0000e6000)({
//   priority: (*uint8)(0xc0000d8028)(1),
//   facility: (*uint8)(0xc0000d8029)(0),
//   severity: (*uint8)(0xc0000d802a)(1),
//   version: (uint16) 1,
//   timestamp: (*time.Time)(<nil>),
//   hostname: (*string)(<nil>),
//   appname: (*string)(<nil>),
//   procID: (*string)(<nil>),
//   msgID: (*string)(<nil>),
//   structuredData: (*map[string]map[string]string)(<nil>),
//   message: (*string)(<nil>)
//  }),
//  Error: (*errors.errorString)(0xc0000d2020)(parsing error [col 4])
// }