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adapter.go
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adapter.go
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package splunktarget
import (
"context"
"crypto/tls"
"encoding/json"
"net/http"
"net/url"
"time"
"go.uber.org/zap"
cloudevents "github.com/cloudevents/sdk-go/v2"
pkgadapter "knative.dev/eventing/pkg/adapter/v2"
"knative.dev/pkg/logging"
"github.com/ZachtimusPrime/Go-Splunk-HTTP/splunk/v2"
"github.com/zeiss/typhoon/pkg/apis/targets"
"github.com/zeiss/typhoon/pkg/metrics"
)
// SplunkClient is the interface that must be implemented by Splunk HEC
// clients.
type SplunkClient interface {
NewEventWithTime(t time.Time, event interface{}, source, sourcetype, index string) *splunk.Event
LogEvent(e *splunk.Event) error
}
// adapter implements the target's adapter.
type adapter struct {
logger *zap.SugaredLogger
ceClient cloudevents.Client
spClient SplunkClient
defaultIndex string
sr *metrics.EventProcessingStatsReporter
discardCEContext bool
}
var _ pkgadapter.Adapter = (*adapter)(nil)
// envConfig is a set parameters sourced from the environment for the target's adapter.
type envConfig struct {
pkgadapter.EnvConfig
HECEndpoint string `envconfig:"SPLUNK_HEC_ENDPOINT" required:"true"`
HECToken string `envconfig:"SPLUNK_HEC_TOKEN" required:"true"`
Index string `envconfig:"SPLUNK_INDEX"`
SkipTLSVerify bool `envconfig:"SPLUNK_SKIP_TLS_VERIFY"`
DiscardCEContext bool `envconfig:"DISCARD_CE_CONTEXT" default:"false"`
}
// NewEnvConfig returns an accessor for the source's adapter envConfig.
func NewEnvConfig() pkgadapter.EnvConfigAccessor {
return &envConfig{}
}
// https://docs.splunk.com/Documentation/Splunk/latest/RESTREF/RESTinput#services.2Fcollector.2Fevent.2F1.0
const eventURLPath = "/services/collector/event/1.0"
const httpTimeout = time.Second * 20
// NewTarget returns a constructor for the target's adapter.
func NewTarget(ctx context.Context, envAcc pkgadapter.EnvConfigAccessor, ceClient cloudevents.Client) pkgadapter.Adapter {
logger := logging.FromContext(ctx)
mt := &pkgadapter.MetricTag{
ResourceGroup: targets.SplunkTargetResource.String(),
Namespace: envAcc.GetNamespace(),
Name: envAcc.GetName(),
}
metrics.MustRegisterEventProcessingStatsView()
env := envAcc.(*envConfig)
hecURL, err := url.Parse(env.HECEndpoint)
if err != nil {
logger.Panicw("Invalid HEC endpoint URL "+env.HECEndpoint, zap.Error(err))
}
return &adapter{
logger: logger,
ceClient: ceClient,
spClient: newClient(*hecURL, env.HECToken, env.Index, hostname(envAcc), env.SkipTLSVerify),
defaultIndex: env.Index,
sr: metrics.MustNewEventProcessingStatsReporter(mt),
discardCEContext: env.DiscardCEContext,
}
}
// newClient returns a Splunk HEC client.
func newClient(hecURL url.URL, hecToken, index, hostname string, skipTLSVerify bool) *splunk.Client {
httpTransport := &http.Transport{
TLSClientConfig: &tls.Config{ // #nosec G402
InsecureSkipVerify: skipTLSVerify,
},
}
httpClient := &http.Client{
Timeout: httpTimeout,
Transport: httpTransport,
}
if hecURL.Path == "" || hecURL.Path == "/" {
hecURL.Path = eventURLPath
}
return &splunk.Client{
HTTPClient: httpClient,
URL: hecURL.String(),
Hostname: hostname,
Token: hecToken,
Index: index,
}
}
// hostname returns the host name to be included in Splunk events' metadata.
func hostname(env pkgadapter.EnvConfigAccessor) string {
return "com.zeiss.splunktarget." + env.GetNamespace() + "." + env.GetName()
}
// Start implements adapter.Adapter.
func (a *adapter) Start(ctx context.Context) error {
errCh := make(chan error)
go func() {
errCh <- a.ceClient.StartReceiver(ctx, a.receive)
}()
return <-errCh
}
// receive implements the handler's receive logic.
func (a *adapter) receive(ctx context.Context, event cloudevents.Event) cloudevents.Result {
a.logger.Debugw("Processing event", zap.Any("event", event))
e := a.spClient.NewEventWithTime(
event.Time(),
event,
event.Source(),
event.Type(),
a.defaultIndex,
)
if a.discardCEContext {
e.Event = string(event.Data())
if event.DataContentType() == cloudevents.ApplicationJSON {
e.Event = json.RawMessage(event.Data())
}
}
err := a.spClient.LogEvent(e)
if err != nil {
a.logger.Errorw("Failed to send event to HEC", zap.Error(err))
return cloudevents.NewHTTPResult(a.extractHTTPStatus(err), "failed to send event to HEC: %s", err)
}
return cloudevents.ResultACK
}
// extractHTTPStatus attempts to extract the HTTP status code from the given
// error, returns "400 Bad Request" otherwise.
func (a *adapter) extractHTTPStatus(err error) int {
if splunkErr, ok := err.(*splunk.EventCollectorResponse); ok {
code, err := splunkErr.Code.HTTPCode()
if err != nil {
a.logger.Warnw("Couldn't determine HTTP status code", zap.Error(err))
return http.StatusBadRequest
}
return code
}
return http.StatusBadRequest
}