Usage example of go-syslog to parse RFC5424 message with best effort mode on

go-syslog-rfc5424-besteffort.go

package main

import (
  "fmt"

  "github.com/davecgh/go-spew/spew"
  "github.com/influxdata/go-syslog/v2/rfc5424"
)

func main() {
  // Obtain our parser
  // Notice that when best effort is in use both message and error return values can be non nil ...
  p := rfc5424.NewParser(rfc5424.WithBestEffort())

  // Let's parse a complete and valid message just for fun
  input1 := []byte(`<165>1 2018-10-11T22:14:15.003Z mymach.it e - 1 [ex@32473 iut="3"] An app event...`)
  spew.Dump(p.Parse(input1))

  // Let's parse the minimally valid syslog message
  input2 := []byte(`<1>1`)
  fmt.Println("We capture it until error on column 4 ...")
  spew.Dump(p.Parse(input2))

  // Create a strict parser to notice what results it gives us with input2
  strict := rfc5424.NewParser()
  fmt.Println("No syslog.Message instance as result, only the error on column 4 ...")
  spew.Dump(strict.Parse(input2))
}

// (*rfc5424.SyslogMessage)(0xc0000522a0)({
//  priority: (*uint8)(0xc00001223b)(165),
//  facility: (*uint8)(0xc00001223c)(20),
//  severity: (*uint8)(0xc00001223d)(5),
//  version: (uint16) 1,
//  timestamp: (*time.Time)(0xc00008e008)(2018-10-11 22:14:15.003 +0000 UTC),
//  hostname: (*string)(0xc00008e020)((len=9) "mymach.it"),
//  appname: (*string)(0xc00008e030)((len=1) "e"),
//  procID: (*string)(<nil>),
//  msgID: (*string)(0xc00008e050)((len=1) "1"),
//  structuredData: (*map[string]map[string]string)(0xc00008e060)((len=1) {
//   (string) (len=8) "ex@32473": (map[string]string) (len=1) {
//    (string) (len=3) "iut": (string) (len=1) "3"
//   }
//  }),
//  message: (*string)(0xc00008e068)((len=15) "An app event...")
// })
// (interface {}) <nil>
// We capture it until error on column 4 ...
// (*rfc5424.SyslogMessage)(0xc000052420)({
//  priority: (*uint8)(0xc000012600)(1),
//  facility: (*uint8)(0xc000012601)(0),
//  severity: (*uint8)(0xc000012602)(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>)
// })
// (*errors.errorString)(0xc00000e380)(parsing error [col 4])
// No syslog.Message instance as result, only the error on column 4 ...
// (interface {}) <nil>
// (*errors.errorString)(0xc00000e3a0)(parsing error [col 4])