func (this *Server) StartDrainer(address string, filter EntryFilter) *Drainer {
c := make(chan Entry)
listener := &Listener{
Channel: c,
Filter: filter,
LastEntry: time.Now(),
}
this.AddListener <- listener
drainer := &Drainer{
Address: address,
Filter: filter,
server: this,
listener: listener,
terminate: make(chan bool, 1),
}
go func() {
var w *syslog.Writer
var err error
for entry := range Throttle(c, 100) {
for {
// If we terminated give up
select {
case <-drainer.terminate:
return
default:
}
// Connect
if w == nil {
log.Printf("connecting to syslog://%v\n", address)
w, err = syslog.Dial("tcp", address, syslog.LOG_INFO, "")
if err != nil {
w = nil
time.Sleep(time.Second * 5)
continue
}
}
// Send the message
_, err = w.Write(entry.Line())
if err != nil {
w.Close()
w = nil
time.Sleep(time.Second * 5)
continue
}
// Successfully sent the message so break
break
}
}
}()
return drainer
}
// New syslog TCP output.
//
// If the network is empty, the local syslog daemon will be used.
func NewSyslogOutput(network, raddr string, priority syslog.Priority, tag string) (Output, error) {
desc := "syslog"
if network != "" {
desc = fmt.Sprintf("syslog at %s://%s", network, raddr)
}
failing := false
var w *syslog.Writer
dial := func() error {
var err error
w, err = syslog.Dial(network, raddr, priority, tag)
if err != nil {
if !failing {
failing = true
fmt.Fprintf(os.Stderr, "Failed to connect to %s: %s\n", desc, err)
}
w = nil
return err
} else if failing {
fmt.Fprintf(os.Stderr, "Connected to %s\n", desc)
failing = false
}
return nil
}
return newDrainingOutput(10240, func(lines [][]byte) error {
// Connect if a connection does not already exist.
if w == nil {
if err := dial(); err != nil {
return err
}
}
// Send data.
first := true
for _, l := range lines {
if len(l) == 0 {
continue
}
n, err := w.Write(l)
// If the first send fails without sending any data, let's attempt
// to reconnect.
if first {
first = false
if n == 0 && err != nil {
fmt.Fprintf(os.Stderr, "Failed to send data to %s: %s - reconnecting...\n", desc, err)
if err = dial(); err != nil {
return err
}
}
}
// Update the payload and handle any errors.
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to send data to %s: %s\n", desc, err)
failing = true
w.Close()
w = nil
return err
}
}
return nil
}, func() {
if w != nil {
w.Close()
}
})
}
func main() {
flag.Parse()
// Set logTarget
if *logTarget == "" {
logger = log.New(os.Stdout, "LOG ", log.LstdFlags)
debugLogger = log.New(os.Stdout, "DEBUG ", log.LstdFlags)
} else {
u, err := url.Parse(*logTarget)
if err != nil {
log.Fatalln("fatal: unable to parse logtarget url", err)
}
query, _ := url.ParseQuery(u.RawQuery)
switch {
case (u.Scheme == "" || u.Scheme == "file") && u.Path != "":
var logFile *os.File
fileMode := os.FileMode(*logPermission)
_, err = os.Stat(u.Path)
if os.IsNotExist(err) {
logFile, err = os.Create(u.Path)
if err != nil {
log.Fatalln("fatal: unable to create log target", err)
}
err = os.Chmod(u.Path, fileMode)
if err != nil {
log.Fatalln("fatal: unable to set file permissions", err)
}
} else {
logFile, err = os.OpenFile(u.Path, os.O_WRONLY|os.O_APPEND, fileMode)
if err != nil {
log.Fatalln("fatal: unable to open log target", err)
}
}
defer logFile.Close()
logTargetWriter = io.Writer(logFile)
// Check if logTarget is writable
_, err = logTargetWriter.Write([]byte(""))
if err != nil {
log.Fatalln("fatal: unable to write to log target")
}
case strings.HasPrefix(u.Scheme, "syslog"):
var syslogLogger *syslog.Writer
var tag string
priority := int(syslog.LOG_NOTICE | syslog.LOG_LOCAL0)
if query["priority"][0] != "" {
priority, err = strconv.Atoi(query["priority"][0])
if err != nil {
log.Fatalln("fatal: unable to connect to syslog", *logTarget, "err:", err)
}
}
if query["tag"][0] != "" {
tag = query["tag"][0]
}
if u.Host == "" {
syslogLogger, err = syslog.New(syslog.Priority(priority), tag)
if err != nil {
log.Fatalln("fatal: unable to connect to syslog", *logTarget, "err:", err)
}
} else {
schemeParts := strings.Split(u.Scheme, "+")
network := "tcp"
if len(schemeParts) > 1 {
network = schemeParts[1]
}
_, _, err := net.SplitHostPort(u.Host)
if err != nil {
u.Host = u.Host + ":514"
}
syslogLogger, err = syslog.Dial(network, u.Host, syslog.Priority(priority), tag)
if err != nil {
log.Fatalln("fatal: unable to connect to syslog", *logTarget, "err:", err)
}
}
defer syslogLogger.Close()
logTargetWriter = io.Writer(syslogLogger)
default:
log.Fatalln("fatal: no valid schema:", *logTarget)
}
logger = log.New(logTargetWriter, "LOG ", log.LstdFlags)
debugLogger = log.New(logTargetWriter, "DEBUG ", log.LstdFlags)
}
// Set log-function based on log level
switch *logLevel {
case 0:
logf = emptyLogf
case 2:
debugf = debugLogf
default:
}
// Write example log lines
logf("log output %s, %d", "string1", 10)
debugf("debug output %s, %d", "string1", 10)
}