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remote_syslog.go
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remote_syslog.go
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package main
import (
"io"
"net"
"os"
"path"
"path/filepath"
"regexp"
"strconv"
"sync"
"time"
"github.com/howbazaar/loggo"
"github.com/papertrail/go-tail/follower"
"github.com/papertrail/remote_syslog2/syslog"
"github.com/papertrail/remote_syslog2/utils"
)
var log = loggo.GetLogger("")
type Server struct {
config *Config
logger *syslog.Logger
registry WorkerRegistry
stopChan chan struct{}
stopped bool
mu sync.RWMutex
}
func NewServer(config *Config) *Server {
return &Server{
config: config,
registry: NewInMemoryRegistry(),
stopChan: make(chan struct{}),
}
}
func (s *Server) Start() error {
if err := s.config.Validate(); err != nil {
return err
}
if !s.config.NoDetach {
utils.Daemonize(s.config.DebugLogFile, s.config.PidFile)
}
loggo.ConfigureLoggers(s.config.LogLevels)
raddr := net.JoinHostPort(s.config.Destination.Host, strconv.Itoa(s.config.Destination.Port))
log.Infof("Connecting to %s over %s", raddr, s.config.Destination.Protocol)
var err error
s.logger, err = syslog.Dial(
s.config.Hostname,
s.config.Destination.Protocol,
raddr, s.config.RootCAs,
s.config.ConnectTimeout,
s.config.WriteTimeout,
s.config.TcpMaxLineLength,
)
if err != nil {
log.Errorf("Initial connection to server failed: %v - connection will be retried", err)
}
go s.tailFiles()
for err = range s.logger.Errors {
log.Errorf("Syslog error: %v", err)
}
return nil
}
func (s *Server) Close() {
s.mu.Lock()
defer s.mu.Unlock()
if !s.stopped {
s.stopped = true
s.stopChan <- struct{}{}
log.Infof("Shutting down...")
s.logger.Close()
}
}
func (s *Server) closing() bool {
s.mu.RLock()
defer s.mu.RUnlock()
return s.stopped
}
// Tails a single file
func (s *Server) tailOne(file, tag string, whence int) {
defer s.registry.Remove(file)
t, err := follower.New(file, follower.Config{
Reopen: true,
Offset: 0,
Whence: whence,
})
if err != nil {
log.Errorf("%s", err)
return
}
if tag == "" {
tag = path.Base(file)
}
for {
select {
case line, ok := <-t.Lines():
if !ok {
if t.Err() != nil {
log.Errorf("%s", t.Err())
}
return
}
if s.closing() {
t.Close()
return
}
if d := line.Discarded(); d > 0 {
log.Infof("Discarded %d NULL bytes", d)
}
l := line.String()
if !matchExps(l, s.config.ExcludePatterns) {
s.logger.Write(syslog.Packet{
Severity: s.config.Severity,
Facility: s.config.Facility,
Time: time.Now(),
Hostname: s.logger.ClientHostname,
Tag: tag,
Token: s.config.Destination.Token,
Message: l,
})
log.Tracef("Forwarding line: %s", l)
} else {
log.Tracef("Not Forwarding line: %s", l)
}
case <-s.stopChan:
t.Close()
return
}
}
}
// Tails files speficied in the globs and re-evaluates the globs
// at the specified interval
func (s *Server) tailFiles() {
log.Debugf("Evaluating globs every %s", s.config.NewFileCheckInterval)
firstPass := true
for {
if s.closing() {
return
}
s.globFiles(firstPass)
time.Sleep(s.config.NewFileCheckInterval)
firstPass = false
}
}
//
func (s *Server) globFiles(firstPass bool) {
log.Debugf("Evaluating file globs")
for _, glob := range s.config.Files {
tag := glob.Tag
files, err := filepath.Glob(utils.ResolvePath(glob.Path))
if err != nil {
log.Errorf("Failed to glob %s: %s", glob.Path, err)
} else if files == nil && firstPass {
log.Errorf("Cannot forward %s, it may not exist", glob.Path)
}
for _, file := range files {
switch {
case s.registry.Exists(file):
log.Debugf("Skipping %s because it is already running", file)
case matchExps(file, s.config.ExcludeFiles):
log.Debugf("Skipping %s because it is excluded by regular expression", file)
default:
log.Infof("Forwarding file: %s", file)
whence := io.SeekStart
// don't read the entire file on startup
if firstPass {
whence = io.SeekEnd
}
s.registry.Add(file)
go s.tailOne(file, tag, whence)
}
}
}
}
// Evaluates each regex against the string. If any one is a match
// the function returns true, otherwise it returns false
func matchExps(value string, expressions []*regexp.Regexp) bool {
for _, exp := range expressions {
if exp.MatchString(value) {
return true
}
}
return false
}
func main() {
c, err := NewConfigFromEnv()
if err != nil {
if err == ErrUsage {
os.Exit(0)
}
log.Criticalf("Failed to configure the application: %s", err)
os.Exit(1)
}
utils.AddSignalHandlers()
s := NewServer(c)
if err = s.Start(); err != nil {
log.Criticalf("Failed to start server: %v", err)
os.Exit(255)
}
}