Start working on #2: Slack alerts

alerting/slack.go

@@ -0,0 +1,31 @@
+package alerting
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"github.com/TwinProduction/gatus/client"
+	"io/ioutil"
+)
+
+type requestBody struct {
+	Text string `json:"text"`
+}
+
+// SendMessage sends a message to the given Slack webhook
+func SendMessage(webhookUrl, msg string) error {
+	body, _ := json.Marshal(requestBody{Text: msg})
+	response, err := client.GetHttpClient().Post(webhookUrl, "application/json", bytes.NewBuffer(body))
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	output, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return fmt.Errorf("unable to read response body: %v", err.Error())
+	}
+	if string(output) != "ok" {
+		return fmt.Errorf("error: %s", string(output))
+	}
+	return nil
+}