feature: slack receiver should use webhook instead of token

pkg/sinks/slack.go

@@ -2,44 +2,41 @@ package sinks
 
 import (
 	"context"
+
 	"github.com/nlopes/slack"
 	"github.com/opsgenie/kubernetes-event-exporter/pkg/kube"
-	"github.com/rs/zerolog/log"
 )
 
 type SlackConfig struct {
-	Token   string            `yaml:"token"`
-	Channel string            `yaml:"channel"`
-	Message string            `yaml:"message"`
-	Fields  map[string]string `yaml:"fields"`
+	Endpoint string            `yaml:endpoint`
+	Message  string            `yaml:"message"`
+	Fields   map[string]string `yaml:"fields"`
 }
 
 type SlackSink struct {
-	cfg    *SlackConfig
-	client *slack.Client
+	cfg *SlackConfig
 }
 
 func NewSlackSink(cfg *SlackConfig) (Sink, error) {
 	return &SlackSink{
-		cfg:    cfg,
-		client: slack.New(cfg.Token),
+		cfg: cfg,
 	}, nil
 }
 
 func (s *SlackSink) Send(ctx context.Context, ev *kube.EnhancedEvent) error {
-	channel, err := GetString(ev, s.cfg.Channel)
+	message, err := GetString(ev, s.cfg.Message)
 	if err != nil {
 		return err
 	}
 
-	message, err := GetString(ev, s.cfg.Message)
+	endpoint, err := GetString(ev, s.cfg.Endpoint)
 	if err != nil {
 		return err
 	}
 
-	options := []slack.MsgOption{slack.MsgOptionText(message, true)}
+	fields := make([]slack.AttachmentField, 0)
+
 	if s.cfg.Fields != nil {
-		fields := make([]slack.AttachmentField, 0)
 		for k, v := range s.cfg.Fields {
 			fieldText, err := GetString(ev, v)
 			if err != nil {
@@ -52,12 +49,22 @@ func (s *SlackSink) Send(ctx context.Context, ev *kube.EnhancedEvent) error {
 				Short: false,
 			})
 		}
-		options = append(options, slack.MsgOptionAttachments(slack.Attachment{Fields: fields}))
 	}
 
-	_ch, _ts, _text, err := s.client.SendMessageContext(ctx, channel, options...)
-	log.Debug().Str("ch", _ch).Str("ts", _ts).Str("text", _text).Err(err).Msg("Slack Response")
-	return err
+	attachment := slack.Attachment{
+		Fields: fields,
+	}
+
+	webhookMessage := slack.WebhookMessage{
+		Text:        message,
+		Attachments: []slack.Attachment{attachment},
+	}
+
+	err := slack.PostWebhook(endpoint, &webhookMessage)
+	if err != nil {
+		return err
+	}
+	return nil
 }
 
 func (s *SlackSink) Close() {