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beat.go
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beat.go
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/*
Package beat provides the functions required to manage the life-cycle of a Beat.
It provides the standard mechanism for launching a Beat. It manages
configuration, logging, and publisher initialization and registers a signal
handler to gracefully stop the process.
Each Beat implementation must implement the `Beater` interface and a `Creator`
to create and initialize the Beater instance. See the `Beater` interface and `Creator`
documentation for more details.
To use this package, create a simple main that invokes the Run() function.
func main() {
if err := beat.Run("mybeat", myVersion, beater.New); err != nil {
os.Exit(1)
}
}
In the example above, the beater package contains the implementation of the
Beater interface and the New method returns a new instance of Beater. The
Beater implementation is placed into its own package so that it can be reused
or combined with other Beats.
Recommendations
* Use the logp package for logging rather than writing to stdout or stderr.
* Do not call os.Exit in any of your code. Return an error instead. Or if your
code needs to exit without an error, return beat.GracefulExit.
*/
package beat
import (
cryptRand "crypto/rand"
"errors"
"flag"
"fmt"
"math"
"math/big"
"math/rand"
"os"
"runtime"
"strings"
"time"
"github.com/elastic/beats/libbeat/cfgfile"
"github.com/elastic/beats/libbeat/common"
"github.com/elastic/beats/libbeat/logp"
"github.com/elastic/beats/libbeat/paths"
"github.com/elastic/beats/libbeat/processors"
"github.com/elastic/beats/libbeat/publisher"
svc "github.com/elastic/beats/libbeat/service"
"github.com/satori/go.uuid"
// Register default processors.
_ "github.com/elastic/beats/libbeat/processors/actions"
_ "github.com/elastic/beats/libbeat/processors/add_cloud_metadata"
)
// Beater is the interface that must be implemented by every Beat. A Beater
// provides the main Run-loop and a Stop method to break the Run-loop.
// Instantiation and Configuration is normally provided by a Beat-`Creator`.
//
// Once the beat is fully configured, the Run() method is invoked. The
// Run()-method implements the beat its run-loop. Once the Run()-method returns,
// the beat shuts down.
//
// The Stop() method is invoked the first time (and only the first time) a
// shutdown signal is received. The Stop()-method normally will stop the Run()-loop,
// such that the beat can gracefully shutdown.
type Beater interface {
// The main event loop. This method should block until signalled to stop by an
// invocation of the Stop() method.
Run(b *Beat) error
// Stop is invoked to signal that the Run method should finish its execution.
// It will be invoked at most once.
Stop()
}
// Creator initializes and configures a new Beater instance used to execute
// the beat its run-loop.
type Creator func(*Beat, *common.Config) (Beater, error)
// Beat contains the basic beat data and the publisher client used to publish
// events.
type Beat struct {
Name string // Beat name.
Version string // Beat version number. Defaults to the libbeat version when an implementation does not set a version.
UUID uuid.UUID // ID assigned to a Beat instance.
RawConfig *common.Config // Raw config that can be unpacked to get Beat specific config data.
Config BeatConfig // Common Beat configuration data.
Publisher publisher.Publisher // Publisher
}
// BeatConfig struct contains the basic configuration of every beat
type BeatConfig struct {
Shipper publisher.ShipperConfig `config:",inline"`
Output map[string]*common.Config `config:"output"`
Logging logp.Logging `config:"logging"`
Processors processors.PluginConfig `config:"processors"`
Path paths.Path `config:"path"`
}
var (
printVersion = flag.Bool("version", false, "Print the version and exit")
)
var debugf = logp.MakeDebug("beat")
// GracefulExit is an error that signals to exit with a code of 0.
var GracefulExit = errors.New("graceful exit")
func init() {
// Initialize runtime random number generator seed using global, shared
// cryptographically strong pseudo random number generator.
//
// On linux Reader might use getrandom(2) or /udev/random. On windows systems
// CryptGenRandom is used.
n, err := cryptRand.Int(cryptRand.Reader, big.NewInt(math.MaxInt64))
var seed int64
if err != nil {
// fallback to current timestamp on error
seed = time.Now().UnixNano()
} else {
seed = n.Int64()
}
rand.Seed(seed)
}
// Run initializes and runs a Beater implementation. name is the name of the
// Beat (e.g. packetbeat or metricbeat). version is version number of the Beater
// implementation. bt is the `Creator` callback for creating a new beater
// instance.
func Run(name, version string, bt Creator) error {
return handleError(newBeat(name, version).launch(bt))
}
// newBeat creates a new beat instance
func newBeat(name, version string) *Beat {
if version == "" {
version = defaultBeatVersion
}
return &Beat{
Name: name,
Version: version,
UUID: uuid.NewV4(),
}
}
func (b *Beat) launch(bt Creator) error {
err := b.handleFlags()
if err != nil {
return err
}
svc.BeforeRun()
defer svc.Cleanup()
if err := b.configure(); err != nil {
return err
}
// load the beats config section
var sub *common.Config
configName := strings.ToLower(b.Name)
if b.RawConfig.HasField(configName) {
sub, err = b.RawConfig.Child(configName, -1)
if err != nil {
return err
}
} else {
sub = common.NewConfig()
}
logp.Info("Setup Beat: %s; Version: %s", b.Name, b.Version)
processors, err := processors.New(b.Config.Processors)
if err != nil {
return fmt.Errorf("error initializing processors: %v", err)
}
debugf("Initializing output plugins")
publisher, err := publisher.New(b.Name, b.Version, b.Config.Output, b.Config.Shipper, processors)
if err != nil {
return fmt.Errorf("error initializing publisher: %v", err)
}
// TODO: some beats race on shutdown with publisher.Stop -> do not call Stop yet,
// but refine publisher to disconnect clients on stop automatically
// defer publisher.Stop()
b.Publisher = publisher
beater, err := bt(b, sub)
if err != nil {
return err
}
// If -configtest was specified, exit now prior to run.
if cfgfile.IsTestConfig() {
fmt.Println("Config OK")
return GracefulExit
}
svc.HandleSignals(beater.Stop)
logp.Info("%s start running.", b.Name)
defer logp.Info("%s stopped.", b.Name)
defer logp.LogTotalExpvars(&b.Config.Logging)
return beater.Run(b)
}
// handleFlags parses the command line flags. It handles the '-version' flag
// and invokes the HandleFlags callback if implemented by the Beat.
func (b *Beat) handleFlags() error {
// Due to a dependence upon the beat name, the default config file path
// must be updated prior to CLI flag handling.
err := cfgfile.ChangeDefaultCfgfileFlag(b.Name)
if err != nil {
return fmt.Errorf("failed to set default config file path: %v", err)
}
flag.Parse()
if *printVersion {
fmt.Printf("%s version %s (%s), libbeat %s\n",
b.Name, b.Version, runtime.GOARCH, defaultBeatVersion)
return GracefulExit
}
if err := cfgfile.HandleFlags(); err != nil {
return err
}
return handleFlags(b)
}
// config reads the configuration file from disk, parses the common options
// defined in BeatConfig, initializes logging, and set GOMAXPROCS if defined
// in the config. Lastly it invokes the Config method implemented by the beat.
func (b *Beat) configure() error {
var err error
cfg, err := cfgfile.Load("")
if err != nil {
return fmt.Errorf("error loading config file: %v", err)
}
b.RawConfig = cfg
err = cfg.Unpack(&b.Config)
if err != nil {
return fmt.Errorf("error unpacking config data: %v", err)
}
err = paths.InitPaths(&b.Config.Path)
if err != nil {
return fmt.Errorf("error setting default paths: %v", err)
}
err = logp.Init(b.Name, &b.Config.Logging)
if err != nil {
return fmt.Errorf("error initializing logging: %v", err)
}
// Disable stderr logging if requested by cmdline flag
logp.SetStderr()
// log paths values to help with troubleshooting
logp.Info(paths.Paths.String())
if b.Config.Shipper.MaxProcs != nil {
maxProcs := *b.Config.Shipper.MaxProcs
if maxProcs > 0 {
runtime.GOMAXPROCS(maxProcs)
}
}
return nil
}
// handleError handles the given error by logging it and then returning the
// error. If the err is nil or is a GracefulExit error then the method will
// return nil without logging anything.
func handleError(err error) error {
if err == nil || err == GracefulExit {
return nil
}
// logp may not be initialized so log the err to stderr too.
logp.Critical("Exiting: %v", err)
fmt.Fprintf(os.Stderr, "Exiting: %v\n", err)
return err
}
// GetDefaultVersion returns the current libbeat version.
func GetDefaultVersion() string {
return defaultBeatVersion
}