locker98/postfix_exporter
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Splits the log source handling with a pluggable interface.

Browse Source 
Provides a cleaner split between log sources, specifically for not
compiling with systemd libraries.

This is in preparation for a new log source to read from Docker.
This commit is contained in:
Tommie Gannert 2020-06-21 01:07:59 +02:00 committed by Bart Vercoulen
parent efcf24731b
commit 82fa993361
No known key found for this signature in database
GPG Key ID: E6D9CA10D6B6AC2B
10 changed files with 568 additions and 246 deletions
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63
logsource.go Normal file
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@ -0,0 +1,63 @@
package main
import (
"fmt"
"io"
"github.com/alecthomas/kingpin"
)
// A LogSourceFactory provides a repository of log sources that can be
// instantiated from command line flags.
type LogSourceFactory interface {
// Init adds the factory's struct fields as flags in the
// application.
Init(*kingpin.Application)
// New attempts to create a new log source. This is called after
// flags have been parsed. Returning `nil, nil`, means the user
// didn't want this log source.
New() (LogSourceCloser, error)
}
type LogSourceCloser interface {
io.Closer
LogSource
}
var logSourceFactories []LogSourceFactory
// RegisterLogSourceFactory can be called from module `init` functions
// to register factories.
func RegisterLogSourceFactory(lsf LogSourceFactory) {
logSourceFactories = append(logSourceFactories, lsf)
}
// InitLogSourceFactories runs Init on all factories. The
// initialization order is arbitrary, except `fileLogSourceFactory` is
// always last (the fallback). The file log source must be last since
// it's enabled by default.
func InitLogSourceFactories(app *kingpin.Application) {
RegisterLogSourceFactory(&fileLogSourceFactory{})
for _, f := range logSourceFactories {
f.Init(app)
}
}
// NewLogSourceFromFactories iterates through the factories and
// attempts to instantiate a log source. The first factory to return
// success wins.
func NewLogSourceFromFactories() (LogSourceCloser, error) {
for _, f := range logSourceFactories {
src, err := f.New()
if err != nil {
return nil, err
}
if src != nil {
return src, nil
}
}
return nil, fmt.Errorf("no log source configured")
}

78
logsource_file.go Normal file
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@ -0,0 +1,78 @@
package main
import (
"context"
"io"
"log"
"github.com/alecthomas/kingpin"
"github.com/hpcloud/tail"
)
// A FileLogSource can read lines from a file.
type FileLogSource struct {
tailer *tail.Tail
}
// NewFileLogSource creates a new log source, tailing the given file.
func NewFileLogSource(path string) (*FileLogSource, error) {
tailer, err := tail.TailFile(path, tail.Config{
ReOpen: true, // reopen the file if it's rotated
MustExist: true, // fail immediately if the file is missing or has incorrect permissions
Follow: true, // run in follow mode
Location: &tail.SeekInfo{Whence: io.SeekEnd}, // seek to end of file
Logger: tail.DiscardingLogger,
})
if err != nil {
return nil, err
}
return &FileLogSource{tailer}, nil
}
func (s *FileLogSource) Close() error {
defer s.tailer.Cleanup()
go func() {
// Stop() waits for the tailer goroutine to shut down, but it
// can be blocking on sending on the Lines channel...
for range s.tailer.Lines {
}
}()
return s.tailer.Stop()
}
func (s *FileLogSource) Path() string {
return s.tailer.Filename
}
func (s *FileLogSource) Read(ctx context.Context) (string, error) {
select {
case line, ok := <-s.tailer.Lines:
if !ok {
return "", io.EOF
}
return line.Text, nil
case <-ctx.Done():
return "", ctx.Err()
}
}
// A fileLogSourceFactory is a factory than can create log sources
// from command line flags.
//
// Because this factory is enabled by default, it must always be
// registered last.
type fileLogSourceFactory struct {
path string
}
func (f *fileLogSourceFactory) Init(app *kingpin.Application) {
app.Flag("postfix.logfile_path", "Path where Postfix writes log entries.").Default("/var/log/maillog").StringVar(&f.path)
}
func (f *fileLogSourceFactory) New() (LogSourceCloser, error) {
if f.path == "" {
return nil, nil
}
log.Printf("Reading log events from %s", f.path)
return NewFileLogSource(f.path)
}

87
logsource_file_test.go Normal file
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@ -0,0 +1,87 @@
package main
import (
"context"
"fmt"
"io/ioutil"
"os"
"sync"
"testing"
"time"
"github.com/stretchr/testify/assert"
)
func TestFileLogSource_Path(t *testing.T) {
path, close, err := setupFakeLogFile()
if err != nil {
t.Fatalf("setupFakeTailer failed: %v", err)
}
defer close()
src, err := NewFileLogSource(path)
if err != nil {
t.Fatalf("NewFileLogSource failed: %v", err)
}
defer src.Close()
assert.Equal(t, path, src.Path(), "Path should be set by New.")
}
func TestFileLogSource_Read(t *testing.T) {
ctx := context.Background()
path, close, err := setupFakeLogFile()
if err != nil {
t.Fatalf("setupFakeTailer failed: %v", err)
}
defer close()
src, err := NewFileLogSource(path)
if err != nil {
t.Fatalf("NewFileLogSource failed: %v", err)
}
defer src.Close()
s, err := src.Read(ctx)
if err != nil {
t.Fatalf("Read failed: %v", err)
}
assert.Equal(t, "Feb 13 23:31:30 ahost anid[123]: aline", s, "Read should get data from the journal entry.")
}
func setupFakeLogFile() (string, func(), error) {
f, err := ioutil.TempFile("", "filelogsource")
if err != nil {
return "", nil, err
}
ctx, cancel := context.WithCancel(context.Background())
var wg sync.WaitGroup
wg.Add(1)
go func() {
defer wg.Done()
defer os.Remove(f.Name())
defer f.Close()
for {
// The tailer seeks to the end and then does a
// follow. Keep writing lines so we know it wakes up and
// returns lines.
fmt.Fprintln(f, "Feb 13 23:31:30 ahost anid[123]: aline")
select {
case <-time.After(10 * time.Millisecond):
// continue
case <-ctx.Done():
return
}
}
}()
return f.Name(), func() {
cancel()
wg.Wait()
}, nil
}

143
logsource_systemd.go Normal file
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@ -0,0 +1,143 @@
// +build !nosystemd,linux
package main
import (
"context"
"fmt"
"io"
"log"
"time"
"github.com/alecthomas/kingpin"
"github.com/coreos/go-systemd/v22/sdjournal"
)
// timeNow is a test fake injection point.
var timeNow = time.Now
// A SystemdLogSource reads log records from the given Systemd
// journal.
type SystemdLogSource struct {
journal SystemdJournal
path string
}
// A SystemdJournal is the journal interface that sdjournal.Journal
// provides. See https://pkg.go.dev/github.com/coreos/go-systemd/sdjournal?tab=doc
type SystemdJournal interface {
io.Closer
AddMatch(match string) error
GetEntry() (*sdjournal.JournalEntry, error)
Next() (uint64, error)
SeekRealtimeUsec(usec uint64) error
Wait(timeout time.Duration) int
}
// NewSystemdLogSource returns a log source for reading Systemd
// journal entries. `unit` and `slice` provide filtering if non-empty
// (with `slice` taking precedence).
func NewSystemdLogSource(j SystemdJournal, path, unit, slice string) (*SystemdLogSource, error) {
logSrc := &SystemdLogSource{journal: j, path: path}
var err error
if slice != "" {
err = logSrc.journal.AddMatch("_SYSTEMD_SLICE=" + slice)
} else if unit != "" {
err = logSrc.journal.AddMatch("_SYSTEMD_UNIT=" + unit)
}
if err != nil {
logSrc.journal.Close()
return nil, err
}
// Start at end of journal
if err := logSrc.journal.SeekRealtimeUsec(uint64(timeNow().UnixNano() / 1000)); err != nil {
logSrc.journal.Close()
return nil, err
}
if r := logSrc.journal.Wait(1 * time.Second); r < 0 {
logSrc.journal.Close()
return nil, err
}
return logSrc, nil
}
func (s *SystemdLogSource) Close() error {
return s.journal.Close()
}
func (s *SystemdLogSource) Path() string {
return s.path
}
func (s *SystemdLogSource) Read(ctx context.Context) (string, error) {
c, err := s.journal.Next()
if err != nil {
return "", err
}
if c == 0 {
return "", io.EOF
}
e, err := s.journal.GetEntry()
if err != nil {
return "", err
}
ts := time.Unix(0, int64(e.RealtimeTimestamp)*int64(time.Microsecond))
return fmt.Sprintf(
"%s %s %s[%s]: %s",
ts.Format(time.Stamp),
e.Fields["_HOSTNAME"],
e.Fields["SYSLOG_IDENTIFIER"],
e.Fields["_PID"],
e.Fields["MESSAGE"],
), nil
}
// A systemdLogSourceFactory is a factory that can create
// SystemdLogSources from command line flags.
type systemdLogSourceFactory struct {
enable bool
unit, slice, path string
}
func (f *systemdLogSourceFactory) Init(app *kingpin.Application) {
app.Flag("systemd.enable", "Read from the systemd journal instead of log").Default("false").BoolVar(&f.enable)
app.Flag("systemd.unit", "Name of the Postfix systemd unit.").Default("postfix.service").StringVar(&f.unit)
app.Flag("systemd.slice", "Name of the Postfix systemd slice. Overrides the systemd unit.").Default("").StringVar(&f.slice)
app.Flag("systemd.journal_path", "Path to the systemd journal").Default("").StringVar(&f.path)
}
func (f *systemdLogSourceFactory) New() (LogSourceCloser, error) {
if !f.enable {
return nil, nil
}
log.Println("Reading log events from systemd")
j, path, err := newSystemdJournal(f.path)
if err != nil {
return nil, err
}
return NewSystemdLogSource(j, path, f.unit, f.slice)
}
// newSystemdJournal creates a journal handle. It returns the handle
// and a string representation of it. If `path` is empty, it connects
// to the local journald.
func newSystemdJournal(path string) (*sdjournal.Journal, string, error) {
if path != "" {
j, err := sdjournal.NewJournalFromDir(path)
return j, path, err
}
j, err := sdjournal.NewJournal()
return j, "journald", err
}
func init() {
RegisterLogSourceFactory(&systemdLogSourceFactory{})
}

150
logsource_systemd_test.go Normal file
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@ -0,0 +1,150 @@
// +build !nosystemd,linux
package main
import (
"context"
"io"
"os"
"testing"
"time"
"github.com/coreos/go-systemd/v22/sdjournal"
"github.com/stretchr/testify/assert"
)
func TestNewSystemdLogSource(t *testing.T) {
j := &fakeSystemdJournal{}
src, err := NewSystemdLogSource(j, "apath", "aunit", "aslice")
if err != nil {
t.Fatalf("NewSystemdLogSource failed: %v", err)
}
assert.Equal(t, []string{"_SYSTEMD_SLICE=aslice"}, j.addMatchCalls, "A match should be added for slice.")
assert.Equal(t, []uint64{1234567890000000}, j.seekRealtimeUsecCalls, "A call to SeekRealtimeUsec should be made.")
assert.Equal(t, []time.Duration{1 * time.Second}, j.waitCalls, "A call to Wait should be made.")
if err := src.Close(); err != nil {
t.Fatalf("Close failed: %v", err)
}
assert.Equal(t, 1, j.closeCalls, "A call to Close should be made.")
}
func TestSystemdLogSource_Path(t *testing.T) {
j := &fakeSystemdJournal{}
src, err := NewSystemdLogSource(j, "apath", "aunit", "aslice")
if err != nil {
t.Fatalf("NewSystemdLogSource failed: %v", err)
}
defer src.Close()
assert.Equal(t, "apath", src.Path(), "Path should be set by New.")
}
func TestSystemdLogSource_Read(t *testing.T) {
ctx := context.Background()
j := &fakeSystemdJournal{
getEntryValues: []sdjournal.JournalEntry{
{
Fields: map[string]string{
"_HOSTNAME": "ahost",
"SYSLOG_IDENTIFIER": "anid",
"_PID": "123",
"MESSAGE": "aline",
},
RealtimeTimestamp: 1234567890000000,
},
},
nextValues: []uint64{1},
}
src, err := NewSystemdLogSource(j, "apath", "aunit", "aslice")
if err != nil {
t.Fatalf("NewSystemdLogSource failed: %v", err)
}
defer src.Close()
s, err := src.Read(ctx)
if err != nil {
t.Fatalf("Read failed: %v", err)
}
assert.Equal(t, "Feb 13 23:31:30 ahost anid[123]: aline", s, "Read should get data from the journal entry.")
}
func TestSystemdLogSource_ReadEOF(t *testing.T) {
ctx := context.Background()
j := &fakeSystemdJournal{
nextValues: []uint64{0},
}
src, err := NewSystemdLogSource(j, "apath", "aunit", "aslice")
if err != nil {
t.Fatalf("NewSystemdLogSource failed: %v", err)
}
defer src.Close()
_, err = src.Read(ctx)
assert.Equal(t, io.EOF, err, "Should interpret Next 0 as EOF.")
}
func TestMain(m *testing.M) {
// We compare Unix timestamps to date strings, so make it deterministic.
os.Setenv("TZ", "UTC")
timeNow = func() time.Time { return time.Date(2009, 2, 13, 23, 31, 30, 0, time.UTC) }
defer func() {
timeNow = time.Now
}()
os.Exit(m.Run())
}
type fakeSystemdJournal struct {
getEntryValues []sdjournal.JournalEntry
getEntryError error
nextValues []uint64
nextError error
addMatchCalls []string
closeCalls int
seekRealtimeUsecCalls []uint64
waitCalls []time.Duration
}
func (j *fakeSystemdJournal) AddMatch(match string) error {
j.addMatchCalls = append(j.addMatchCalls, match)
return nil
}
func (j *fakeSystemdJournal) Close() error {
j.closeCalls++
return nil
}
func (j *fakeSystemdJournal) GetEntry() (*sdjournal.JournalEntry, error) {
if len(j.getEntryValues) == 0 {
return nil, j.getEntryError
}
e := j.getEntryValues[0]
j.getEntryValues = j.getEntryValues[1:]
return &e, nil
}
func (j *fakeSystemdJournal) Next() (uint64, error) {
if len(j.nextValues) == 0 {
return 0, j.nextError
}
v := j.nextValues[0]
j.nextValues = j.nextValues[1:]
return v, nil
}
func (j *fakeSystemdJournal) SeekRealtimeUsec(usec uint64) error {
j.seekRealtimeUsecCalls = append(j.seekRealtimeUsecCalls, usec)
return nil
}
func (j *fakeSystemdJournal) Wait(timeout time.Duration) int {
j.waitCalls = append(j.waitCalls, timeout)
return 0
}

33
main.go
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@ -13,36 +13,25 @@ import (
func main() {
var (
app = kingpin.New("postfix_exporter", "Prometheus metrics exporter for postfix")
listenAddress = app.Flag("web.listen-address", "Address to listen on for web interface and telemetry.").Default(":9154").String()
metricsPath = app.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
postfixShowqPath = app.Flag("postfix.showq_path", "Path at which Postfix places its showq socket.").Default("/var/spool/postfix/public/showq").String()
postfixLogfilePath = app.Flag("postfix.logfile_path", "Path where Postfix writes log entries.").Default("/var/log/maillog").String()
logUnsupportedLines = app.Flag("log.unsupported", "Log all unsupported lines.").Bool()
systemdEnable bool
systemdUnit, systemdSlice, systemdJournalPath string
app = kingpin.New("postfix_exporter", "Prometheus metrics exporter for postfix")
listenAddress = app.Flag("web.listen-address", "Address to listen on for web interface and telemetry.").Default(":9154").String()
metricsPath = app.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
postfixShowqPath = app.Flag("postfix.showq_path", "Path at which Postfix places its showq socket.").Default("/var/spool/postfix/public/showq").String()
logUnsupportedLines = app.Flag("log.unsupported", "Log all unsupported lines.").Bool()
)
systemdFlags(&systemdEnable, &systemdUnit, &systemdSlice, &systemdJournalPath, app)
InitLogSourceFactories(app)
kingpin.MustParse(app.Parse(os.Args[1:]))
var journal *Journal
if systemdEnable {
var err error
journal, err = NewJournal(systemdUnit, systemdSlice, systemdJournalPath)
if err != nil {
log.Fatalf("Error opening systemd journal: %s", err)
}
defer journal.Close()
log.Println("Reading log events from systemd")
} else {
log.Printf("Reading log events from %v", *postfixLogfilePath)
logSrc, err := NewLogSourceFromFactories()
if err != nil {
log.Fatalf("Error opening log source: %s", err)
}
defer logSrc.Close()
exporter, err := NewPostfixExporter(
*postfixShowqPath,
*postfixLogfilePath,
journal,
logSrc,
*logUnsupportedLines,
)
if err != nil {

25
nosystemd.go
View File

@ -1,25 +0,0 @@
// +build nosystemd !linux
// This file contains stubs to support non-systemd use
package main
import (
"io"
"github.com/alecthomas/kingpin"
)
type Journal struct {
io.Closer
Path string
}
func systemdFlags(enable *bool, unit, slice, path *string, app *kingpin.Application) {}
func NewJournal(unit, slice, path string) (*Journal, error) {
return nil, nil
}
func (e *PostfixExporter) CollectLogfileFromJournal() error {
return nil
}

106
postfix_exporter.go
View File

@ -27,7 +27,6 @@ import (
"strings"
"time"
"github.com/hpcloud/tail"
"github.com/prometheus/client_golang/prometheus"
)
@ -42,8 +41,7 @@ var (
// Postfix Prometheus metrics exporter across scrapes.
type PostfixExporter struct {
showqPath string
journal *Journal
tailer *tail.Tail
logSrc LogSource
logUnsupportedLines bool
// Metrics that should persist after refreshes, based on logs.
@ -72,6 +70,16 @@ type PostfixExporter struct {
opendkimSignatureAdded *prometheus.CounterVec
}
// A LogSource is an interface to read log lines.
type LogSource interface {
// Path returns a representation of the log location.
Path() string
// Read returns the next log line. Returns `io.EOF` at the end of
// the log.
Read(context.Context) (string, error)
}
// CollectShowqFromReader parses the output of Postfix's 'showq' command
// and turns it into metrics.
//
@ -420,50 +428,13 @@ func addToHistogramVec(h *prometheus.HistogramVec, value, fieldName string, labe
h.WithLabelValues(labels...).Observe(float)
}
// CollectLogfileFromFile tails a Postfix log file and collects entries from it.
func (e *PostfixExporter) CollectLogfileFromFile(ctx context.Context) {
gaugeVec := prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: "postfix",
Subsystem: "",
Name: "up",
Help: "Whether scraping Postfix's metrics was successful.",
},
[]string{"path"})
gauge := gaugeVec.WithLabelValues(e.tailer.Filename)
for {
select {
case line := <-e.tailer.Lines:
e.CollectFromLogLine(line.Text)
case <-ctx.Done():
gauge.Set(0)
return
}
gauge.Set(1)
}
}
// NewPostfixExporter creates a new Postfix exporter instance.
func NewPostfixExporter(showqPath string, logfilePath string, journal *Journal, logUnsupportedLines bool) (*PostfixExporter, error) {
var tailer *tail.Tail
if logfilePath != "" {
var err error
tailer, err = tail.TailFile(logfilePath, tail.Config{
ReOpen: true, // reopen the file if it's rotated
MustExist: true, // fail immediately if the file is missing or has incorrect permissions
Follow: true, // run in follow mode
Location: &tail.SeekInfo{Whence: io.SeekEnd}, // seek to end of file
})
if err != nil {
return nil, err
}
}
func NewPostfixExporter(showqPath string, logSrc LogSource, logUnsupportedLines bool) (*PostfixExporter, error) {
timeBuckets := []float64{1e-3, 1e-2, 1e-1, 1.0, 10, 1 * 60, 1 * 60 * 60, 24 * 60 * 60, 2 * 24 * 60 * 60}
return &PostfixExporter{
logUnsupportedLines: logUnsupportedLines,
showqPath: showqPath,
tailer: tailer,
journal: journal,
logSrc: logSrc,
cleanupProcesses: prometheus.NewCounter(prometheus.CounterOpts{
Namespace: "postfix",
@ -613,7 +584,7 @@ func NewPostfixExporter(showqPath string, logfilePath string, journal *Journal,
func (e *PostfixExporter) Describe(ch chan<- *prometheus.Desc) {
ch <- postfixUpDesc
if e.tailer == nil && e.journal == nil {
if e.logSrc == nil {
return
}
ch <- e.cleanupProcesses.Desc()
@ -641,38 +612,12 @@ func (e *PostfixExporter) Describe(ch chan<- *prometheus.Desc) {
e.opendkimSignatureAdded.Describe(ch)
}
func (e *PostfixExporter) foreverCollectFromJournal(ctx context.Context) {
gauge := prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: "postfix",
Subsystem: "",
Name: "up",
Help: "Whether scraping Postfix's metrics was successful.",
},
[]string{"path"}).WithLabelValues(e.journal.Path)
select {
case <-ctx.Done():
gauge.Set(0)
return
default:
err := e.CollectLogfileFromJournal()
if err != nil {
log.Printf("Couldn't read journal: %v", err)
gauge.Set(0)
} else {
gauge.Set(1)
}
}
}
func (e *PostfixExporter) StartMetricCollection(ctx context.Context) {
if e.journal != nil {
e.foreverCollectFromJournal(ctx)
} else if e.tailer != nil {
e.CollectLogfileFromFile(ctx)
if e.logSrc == nil {
return
}
prometheus.NewGaugeVec(
gaugeVec := prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: "postfix",
Subsystem: "",
@ -680,7 +625,20 @@ func (e *PostfixExporter) StartMetricCollection(ctx context.Context) {
Help: "Whether scraping Postfix's metrics was successful.",
},
[]string{"path"})
return
gauge := gaugeVec.WithLabelValues(e.logSrc.Path())
defer gauge.Set(0)
for {
line, err := e.logSrc.Read(ctx)
if err != nil {
if err != io.EOF {
log.Printf("Couldn't read journal: %v", err)
}
return
}
e.CollectFromLogLine(line)
gauge.Set(1)
}
}
// Collect metrics from Postfix's showq socket and its log file.
@ -701,7 +659,7 @@ func (e *PostfixExporter) Collect(ch chan<- prometheus.Metric) {
e.showqPath)
}
if e.tailer == nil && e.journal == nil {
if e.logSrc == nil {
return
}
ch <- e.cleanupProcesses

10
postfix_exporter_test.go
View File

@ -1,18 +1,17 @@
package main
import (
"github.com/hpcloud/tail"
"testing"
"github.com/prometheus/client_golang/prometheus"
io_prometheus_client "github.com/prometheus/client_model/go"
"github.com/stretchr/testify/assert"
"testing"
)
func TestPostfixExporter_CollectFromLogline(t *testing.T) {
type fields struct {
showqPath string
journal *Journal
tailer *tail.Tail
logSrc LogSource
cleanupProcesses prometheus.Counter
cleanupRejects prometheus.Counter
cleanupNotAccepted prometheus.Counter
@ -173,8 +172,7 @@ func TestPostfixExporter_CollectFromLogline(t *testing.T) {
t.Run(tt.name, func(t *testing.T) {
e := &PostfixExporter{
showqPath: tt.fields.showqPath,
journal: tt.fields.journal,
tailer: tt.fields.tailer,
logSrc: tt.fields.logSrc,
cleanupProcesses: tt.fields.cleanupProcesses,
cleanupRejects: tt.fields.cleanupRejects,
cleanupNotAccepted: tt.fields.cleanupNotAccepted,

119
systemd.go
View File

@ -1,119 +0,0 @@
// +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
}