slack-bot/pkg/notify/slack.go

package notify

import (
	"context"
	"fmt"
	"log"

	"github.com/slack-go/slack"
)

type SlackContextKey string

const (
	slackHookBaseURL                 = "hooks.slack.com/services"
	DryRunContextKey SlackContextKey = "dryRun"
)

//Notifier interface represent mean to send notification
type Notifier interface {
	Notify(message string)
}

//Message store and represent alerting message
type Message struct {
	ShouldNotify bool
	Content      string
}

type SlackNotifier struct {
	BotID         string
	DestChannelID string
	WebhookID     string
}

//NewSlackNotifier create slack notifier
func NewSlackNotifier(BotID, DestChannelID, WebhookID string) *SlackNotifier {
	return &SlackNotifier{
		BotID:         BotID,
		DestChannelID: DestChannelID,
		WebhookID:     WebhookID,
	}
}

//Notify send notification to channel
func (sn *SlackNotifier) Notify(ctx context.Context, messages ...Message) {
	shouldNotify := false
	var content string
	for _, message := range messages {
		if message.ShouldNotify {
			shouldNotify = true
			content = fmt.Sprintf("%s\n%s", content, message.Content)
		}
	}
	if shouldNotify {
		msg := &slack.WebhookMessage{
			Text: content,
		}

		url := fmt.Sprintf("https://%s/%s/%s/%s", slackHookBaseURL, sn.BotID, sn.DestChannelID, sn.WebhookID)
		if v := ctx.Value(DryRunContextKey); v != nil && v == true {
			log.Printf("dryrun mode : slack notify to %s\n", url)
			log.Printf("dryrun mode : %+v\n", msg)
		} else {
			err := slack.PostWebhook(url, msg)
			if err != nil {
				log.Printf("Send message error %+v", err)
			}
		}
	}
}