postfix_exporter/systemd.go
2020-02-12 13:41:29 +01:00

120 lines
2.5 KiB
Go

// +build !nosystemd,linux
package main
import (
"fmt"
"log"
"sync"
"time"
"github.com/alecthomas/kingpin"
"github.com/coreos/go-systemd/v22/sdjournal"
)
// Journal represents a lockable systemd journal.
type Journal struct {
*sdjournal.Journal
sync.Mutex
Path string
}
// NewJournal returns a Journal for reading journal entries.
func NewJournal(unit, slice, path string) (j *Journal, err error) {
j = new(Journal)
if path != "" {
j.Journal, err = sdjournal.NewJournalFromDir(path)
j.Path = path
} else {
j.Journal, err = sdjournal.NewJournal()
j.Path = "journald"
}
if err != nil {
return
}
if slice != "" {
err = j.AddMatch("_SYSTEMD_SLICE=" + slice)
if err != nil {
return
}
} else if unit != "" {
err = j.AddMatch("_SYSTEMD_UNIT=" + unit)
if err != nil {
return
}
}
// Start at end of journal
err = j.SeekRealtimeUsec(uint64(time.Now().UnixNano() / 1000))
if err != nil {
log.Printf("%v", err)
}
return
}
// NextMessage reads the next message from the journal.
func (j *Journal) NextMessage() (s string, c uint64, err error) {
var e *sdjournal.JournalEntry
// Read to next
c, err = j.Next()
if err != nil {
return
}
// Return when on the end of journal
if c == 0 {
return
}
// Get entry
e, err = j.GetEntry()
if err != nil {
return
}
ts := time.Unix(0, int64(e.RealtimeTimestamp)*int64(time.Microsecond))
// Format entry
s = fmt.Sprintf(
"%s %s %s[%s]: %s",
ts.Format(time.Stamp),
e.Fields["_HOSTNAME"],
e.Fields["SYSLOG_IDENTIFIER"],
e.Fields["_PID"],
e.Fields["MESSAGE"],
)
return
}
// systemdFlags sets the flags for use with systemd
func systemdFlags(enable *bool, unit, slice, path *string, app *kingpin.Application) {
app.Flag("systemd.enable", "Read from the systemd journal instead of log").Default("false").BoolVar(enable)
app.Flag("systemd.unit", "Name of the Postfix systemd unit.").Default("postfix.service").StringVar(unit)
app.Flag("systemd.slice", "Name of the Postfix systemd slice. Overrides the systemd unit.").Default("").StringVar(slice)
app.Flag("systemd.journal_path", "Path to the systemd journal").Default("").StringVar(path)
}
// CollectLogfileFromJournal Collects entries from the systemd journal.
func (e *PostfixExporter) CollectLogfileFromJournal() error {
e.journal.Lock()
defer e.journal.Unlock()
r := e.journal.Wait(time.Duration(1) * time.Second)
if r < 0 {
log.Print("error while waiting for journal!")
}
for {
m, c, err := e.journal.NextMessage()
if err != nil {
return err
}
if c == 0 {
break
}
e.CollectFromLogline(m)
}
return nil
}