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kafka.go
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kafka.go
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package kafka
import (
"context"
"encoding/json"
"fmt"
"github.com/prometheus/alertmanager/notify"
"github.com/prometheus/alertmanager/types"
"github.com/prometheus/common/model"
"github.com/grafana/alerting/images"
"github.com/grafana/alerting/logging"
"github.com/grafana/alerting/receivers"
"github.com/grafana/alerting/templates"
)
type kafkaBody struct {
Records []kafkaRecordEnvelope `json:"records"`
}
type kafkaRecordEnvelope struct {
Value kafkaRecord `json:"value"`
}
type kafkaRecord struct {
Description string `json:"description"`
Client string `json:"client,omitempty"`
Details string `json:"details,omitempty"`
AlertState receivers.AlertStateType `json:"alert_state,omitempty"`
ClientURL string `json:"client_url,omitempty"`
Contexts []kafkaContext `json:"contexts,omitempty"`
IncidentKey string `json:"incident_key,omitempty"`
}
type kafkaV3Record struct {
Type string `json:"type"`
Data kafkaRecord `json:"data"`
}
type kafkaContext struct {
Type string `json:"type"`
Source string `json:"src"`
}
// Notifier is responsible for sending
// alert notifications to Kafka.
type Notifier struct {
*receivers.Base
log logging.Logger
images images.Provider
ns receivers.WebhookSender
tmpl *templates.Template
settings Config
}
func New(cfg Config, meta receivers.Metadata, template *templates.Template, sender receivers.WebhookSender, images images.Provider, logger logging.Logger) *Notifier {
return &Notifier{
Base: receivers.NewBase(meta),
log: logger,
ns: sender,
images: images,
tmpl: template,
settings: cfg,
}
}
// Notify sends the alert notification.
func (kn *Notifier) Notify(ctx context.Context, as ...*types.Alert) (bool, error) {
if kn.settings.APIVersion == apiVersionV3 {
return kn.notifyWithAPIV3(ctx, as...)
}
return kn.notifyWithAPIV2(ctx, as...)
}
// Use the v2 API to send the alert notification.
func (kn *Notifier) notifyWithAPIV2(ctx context.Context, as ...*types.Alert) (bool, error) {
var tmplErr error
tmpl, _ := templates.TmplText(ctx, kn.tmpl, as, kn.log, &tmplErr)
topicURL := kn.settings.Endpoint + "/topics/" + tmpl(kn.settings.Topic)
if tmplErr != nil {
kn.log.Warn("failed to template Kafka url", "error", tmplErr.Error())
}
body, err := kn.buildBody(ctx, tmpl, as...)
if err != nil {
return false, err
}
if tmplErr != nil {
kn.log.Warn("failed to template Kafka message", "error", tmplErr.Error())
}
cmd := &receivers.SendWebhookSettings{
URL: topicURL,
Body: body,
HTTPMethod: "POST",
HTTPHeader: map[string]string{
"Content-Type": "application/vnd.kafka.json.v2+json",
"Accept": "application/vnd.kafka.v2+json",
},
User: kn.settings.Username,
Password: kn.settings.Password,
}
if err := kn.ns.SendWebhook(ctx, cmd); err != nil {
kn.log.Error("Failed to send notification to Kafka", "error", err, "body", body)
return false, err
}
return true, nil
}
// Use the v3 API to send the alert notification.
func (kn *Notifier) notifyWithAPIV3(ctx context.Context, as ...*types.Alert) (bool, error) {
var tmplErr error
tmpl, _ := templates.TmplText(ctx, kn.tmpl, as, kn.log, &tmplErr)
// For v3 the Produce URL is like this,
// <Endpoint>/v3/clusters/<KafkaClusterID>/topics/<Topic>/records
topicURL := kn.settings.Endpoint + "/v3/clusters/" + tmpl(kn.settings.KafkaClusterID) + "/topics/" + tmpl(kn.settings.Topic) + "/records"
if tmplErr != nil {
kn.log.Warn("failed to template Kafka url", "error", tmplErr.Error())
}
body, err := kn.buildV3Body(ctx, tmpl, as...)
if err != nil {
return false, err
}
if tmplErr != nil {
kn.log.Warn("failed to template Kafka message", "error", tmplErr.Error())
}
cmd := &receivers.SendWebhookSettings{
URL: topicURL,
Body: body,
HTTPMethod: "POST",
HTTPHeader: map[string]string{
"Content-Type": "application/json",
"Accept": "application/json",
},
Validation: validateKafkaV3Response,
User: kn.settings.Username,
Password: kn.settings.Password,
}
// TODO: Convert to a stream - keep a single connection open and send records on it.
// Can be implemented nicely using receivers. The v3 API can be used in streaming mode
// by setting “Transfer-Encoding: chunked” header.
// For as long as the connection is kept open, the server will keep accepting records.
if err := kn.ns.SendWebhook(ctx, cmd); err != nil {
kn.log.Error("Failed to send notification to Kafka", "error", err, "body", body)
return false, err
}
return true, nil
}
/*
A sample of V3 response looks like this,
{
"error_code": 200,
"cluster_id": "lkc-abcd",
"topic_name": "myTopic",
"partition_id": 5,
"offset": 0,
"timestamp": "2023-01-08T11:21:48.031Z",
"value": { "type" : "JSON", "size" : 14 }
}
*/
type kafkaV3Response struct {
ErrorCode int `json:"error_code"`
}
func validateKafkaV3Response(rawResponse []byte, statusCode int) error {
if statusCode/100 != 2 {
return fmt.Errorf("unexpected status code %d", statusCode)
}
// 200 status means the API was processed successfully.
// The message publishing could still fail. This is verified by checking the error_code field in the response.
var response kafkaV3Response
if err := json.Unmarshal(rawResponse, &response); err != nil {
return err
}
if response.ErrorCode/100 != 2 {
return fmt.Errorf("failed to publish message to Kafka. response: %s", string(rawResponse))
}
return nil
}
func (kn *Notifier) SendResolved() bool {
return !kn.GetDisableResolveMessage()
}
func (kn *Notifier) buildBody(ctx context.Context, tmpl func(string) string, as ...*types.Alert) (string, error) {
if kn.settings.APIVersion == apiVersionV3 {
return kn.buildV3Body(ctx, tmpl, as...)
}
return kn.buildV2Body(ctx, tmpl, as...)
}
func (kn *Notifier) buildV2Body(ctx context.Context, tmpl func(string) string, as ...*types.Alert) (string, error) {
var record kafkaRecord
if err := kn.buildKafkaRecord(ctx, &record, tmpl, as...); err != nil {
return "", err
}
records := kafkaBody{
Records: []kafkaRecordEnvelope{
{Value: record},
},
}
body, err := json.Marshal(records)
if err != nil {
return "", err
}
return string(body), nil
}
func (kn *Notifier) buildV3Body(ctx context.Context, tmpl func(string) string, as ...*types.Alert) (string, error) {
var record kafkaRecord
if err := kn.buildKafkaRecord(ctx, &record, tmpl, as...); err != nil {
return "", err
}
records := map[string]kafkaV3Record{
"value": {
Type: "JSON",
Data: record,
},
}
body, err := json.Marshal(records)
if err != nil {
return "", err
}
return string(body), nil
}
func (kn *Notifier) buildKafkaRecord(ctx context.Context, record *kafkaRecord, tmpl func(string) string, as ...*types.Alert) error {
record.Client = "Grafana"
record.Description = tmpl(kn.settings.Description)
record.Details = tmpl(kn.settings.Details)
state := buildState(as...)
kn.log.Debug("notifying Kafka", "alert_state", state)
record.AlertState = state
ruleURL := receivers.JoinURLPath(kn.tmpl.ExternalURL.String(), "/alerting/list", kn.log)
record.ClientURL = ruleURL
contexts := buildContextImages(ctx, kn.log, kn.images, as...)
if len(contexts) > 0 {
record.Contexts = contexts
}
groupKey, err := notify.ExtractGroupKey(ctx)
if err != nil {
return err
}
record.IncidentKey = groupKey.Hash()
return nil
}
func buildState(as ...*types.Alert) receivers.AlertStateType {
// We are using the state from 7.x to not break kafka.
// TODO: should we switch to the new ones?
if types.Alerts(as...).Status() == model.AlertResolved {
return receivers.AlertStateOK
}
return receivers.AlertStateAlerting
}
func buildContextImages(ctx context.Context, l logging.Logger, imageProvider images.Provider, as ...*types.Alert) []kafkaContext {
var contexts []kafkaContext
_ = images.WithStoredImages(ctx, l, imageProvider,
func(_ int, image images.Image) error {
if image.URL != "" {
contexts = append(contexts, kafkaContext{
Type: "image",
Source: image.URL,
})
}
return nil
}, as...)
return contexts
}