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autodiscover.go
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/
autodiscover.go
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package autodiscover
import (
"github.com/elastic/beats/libbeat/autodiscover/meta"
"github.com/elastic/beats/libbeat/cfgfile"
"github.com/elastic/beats/libbeat/common"
"github.com/elastic/beats/libbeat/common/bus"
"github.com/elastic/beats/libbeat/logp"
"github.com/mitchellh/hashstructure"
)
const debugK = "autodiscover"
// TODO autodiscover providers config reload
// Adapter must be implemented by the beat in order to provide Autodiscover
type Adapter interface {
// TODO Hints
// CreateConfig generates a valid list of configs from the given event, the received event will have all keys defined by `StartFilter`
CreateConfig(bus.Event) ([]*common.Config, error)
// CheckConfig tests given config to check if it will work or not, returns errors in case it won't work
CheckConfig(*common.Config) error
// RunnerFactory provides runner creation by feeding valid configs
cfgfile.RunnerFactory
// EventFilter returns the bus filter to retrieve runner start/stop triggering events
EventFilter() []string
}
// Autodiscover process, it takes a beat adapter and user config and runs autodiscover process, spawning
// new modules when any configured providers does a match
type Autodiscover struct {
bus bus.Bus
adapter Adapter
providers []Provider
runners *cfgfile.Registry
meta *meta.Map
listener bus.Listener
}
// NewAutodiscover instantiates and returns a new Autodiscover manager
func NewAutodiscover(name string, adapter Adapter, config *Config) (*Autodiscover, error) {
// Init Event bus
bus := bus.New(name)
// Init providers
var providers []Provider
for _, providerCfg := range config.Providers {
provider, err := ProviderRegistry.BuildProvider(bus, providerCfg)
if err != nil {
return nil, err
}
logp.Debug(debugK, "Configured autodiscover provider: %s", provider)
providers = append(providers, provider)
}
return &Autodiscover{
bus: bus,
adapter: adapter,
runners: cfgfile.NewRegistry(),
providers: providers,
meta: meta.NewMap(),
}, nil
}
// Start autodiscover process
func (a *Autodiscover) Start() {
if a == nil {
return
}
logp.Info("Starting autodiscover manager")
a.listener = a.bus.Subscribe(a.adapter.EventFilter()...)
for _, provider := range a.providers {
provider.Start()
}
go a.worker()
}
func (a *Autodiscover) worker() {
for event := range a.listener.Events() {
// This will happen on Stop:
if event == nil {
return
}
if _, ok := event["start"]; ok {
a.handleStart(event)
}
if _, ok := event["stop"]; ok {
a.handleStop(event)
}
}
}
func (a *Autodiscover) handleStart(event bus.Event) {
configs, err := a.adapter.CreateConfig(event)
if err != nil {
logp.Debug(debugK, "Could not generate config from event %v: %v", event, err)
return
}
logp.Debug(debugK, "Got a start event: %v, generated configs: %+v", event, configs)
meta := getMeta(event)
for _, config := range configs {
rawCfg := map[string]interface{}{}
if err := config.Unpack(rawCfg); err != nil {
logp.Debug(debugK, "Error unpacking config: %v", err)
continue
}
hash, err := hashstructure.Hash(rawCfg, nil)
if err != nil {
logp.Debug(debugK, "Could not hash config %v: %v", config, err)
continue
}
err = a.adapter.CheckConfig(config)
if err != nil {
logp.Debug(debugK, "Check failed for config %v: %v, won't start runner", config, err)
continue
}
// Update meta no matter what
dynFields := a.meta.Store(hash, meta)
if a.runners.Has(hash) {
logp.Debug(debugK, "Config %v is already running", config)
continue
}
runner, err := a.adapter.Create(config, &dynFields)
if err != nil {
logp.Debug(debugK, "Failed to create runner with config %v: %v", config, err)
continue
}
logp.Info("Autodiscover starting runner: %s", runner)
a.runners.Add(hash, runner)
runner.Start()
}
}
func (a *Autodiscover) handleStop(event bus.Event) {
configs, err := a.adapter.CreateConfig(event)
if err != nil {
logp.Debug(debugK, "Could not generate config from event %v: %v", event, err)
return
}
logp.Debug(debugK, "Got a stop event: %v, generated configs: %+v", event, configs)
for _, config := range configs {
rawCfg := map[string]interface{}{}
if err := config.Unpack(rawCfg); err != nil {
logp.Debug(debugK, "Error unpacking config: %v", err)
continue
}
hash, err := hashstructure.Hash(rawCfg, nil)
if err != nil {
logp.Debug(debugK, "Could not hash config %v: %v", config, err)
continue
}
if !a.runners.Has(hash) {
logp.Debug(debugK, "Config %v is not running", config)
continue
}
if runner := a.runners.Get(hash); runner != nil {
logp.Info("Autodiscover stopping runner: %s", runner)
runner.Stop()
a.runners.Remove(hash)
} else {
logp.Debug(debugK, "Runner not found for stopping: %s", hash)
}
}
}
func getMeta(event bus.Event) common.MapStr {
m := event["meta"]
if m == nil {
return nil
}
logp.Debug(debugK, "Got a meta field in the event")
meta, ok := m.(common.MapStr)
if !ok {
logp.Err("Got a wrong meta field for event %v", event)
return nil
}
return meta
}
// Stop autodiscover process
func (a *Autodiscover) Stop() {
if a == nil {
return
}
// Stop listening for events
a.listener.Stop()
// Stop providers
for _, provider := range a.providers {
provider.Stop()
}
// Stop runners
for hash, runner := range a.runners.CopyList() {
runner.Stop()
a.meta.Remove(hash)
}
logp.Info("Stopped autodiscover manager")
}