Add mail alert

go.mod

@@ -20,6 +20,7 @@ require (
 	google.golang.org/grpc v1.27.1
 	google.golang.org/protobuf v1.25.0
 	gopkg.in/ini.v1 v1.52.0 // indirect
+	gopkg.in/mail.v2 v2.3.1
 	gorm.io/driver/postgres v1.0.0
 	gorm.io/gorm v1.20.1
 )

go.sum

@@ -413,6 +413,8 @@ gopkg.in/ini.v1 v1.51.0 h1:AQvPpx3LzTDM0AjnIRlVFwFFGC+npRopjZxLJj6gdno=
 gopkg.in/ini.v1 v1.51.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
 gopkg.in/ini.v1 v1.52.0 h1:j+Lt/M1oPPejkniCg1TkWE2J3Eh1oZTsHSXzMTzUXn4=
 gopkg.in/ini.v1 v1.52.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
+gopkg.in/mail.v2 v2.3.1 h1:WYFn/oANrAGP2C0dcV6/pbkPzv8yGzqTjPmTeO7qoXk=
+gopkg.in/mail.v2 v2.3.1/go.mod h1:htwXN1Qh09vZJ1NVKxQqHPBaCBbzKhp5GzuJEA4VJWw=
 gopkg.in/resty.v1 v1.12.0/go.mod h1:mDo4pnntr5jdWRML875a/NmxYqAlA73dVijT2AXvQQo=
 gopkg.in/yaml.v2 v2.0.0-20170812160011-eb3733d160e7/go.mod h1:JAlM8MvJe8wmxCU4Bli9HhUf9+ttbYbLASfIpnQbh74=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

pkg/alerter/discord/alerter.go

@@ -103,8 +103,8 @@ func (a *Alerter) alert(ctx context.Context, metric checker.Metric, alt alerter.
 	if err != nil {
 		return fmt.Errorf("cannot read response: %v", err)
 	}
-	if len(buf.String()) > 0 {
-		return fmt.Errorf(buf.String())
+	if buf.Len() > 0 {
+		return fmt.Errorf("invalid response from discord: %s", buf.String())
 	}
 
 	return nil

pkg/alerter/mail/alerter.go

@@ -0,0 +1,100 @@
+// Copyright (c) 2020 SDSLabs
+// Use of this source code is governed by an MIT license
+// details of which can be found in the LICENSE file.
+
+package mail
+
+import (
+	"context"
+	"fmt"
+
+	gomail "gopkg.in/mail.v2"
+
+	"github.com/sdslabs/pinger/pkg/alerter"
+	"github.com/sdslabs/pinger/pkg/appcontext"
+	"github.com/sdslabs/pinger/pkg/checker"
+
+	"github.com/sirupsen/logrus"
+)
+
+// serviceName is the name of the service used to send the alert.
+const serviceName = "mail"
+
+func init() {
+	alerter.Register(serviceName, func() alerter.Alerter { return new(Alerter) })
+}
+
+// senderDetails stores the config for sending E-mail.
+type senderDetails struct {
+	Host   string
+	Port   uint16
+	User   string
+	Secret string
+}
+
+// Alerter sends an alert for test status.
+type Alerter struct {
+	log    *logrus.Logger
+	sender senderDetails
+}
+
+// Provision initializes required fields for a's execution.
+func (a *Alerter) Provision(ctx *appcontext.Context, prov alerter.Provider) error {
+	a.log = ctx.Logger()
+	a.sender = senderDetails{prov.GetHost(), prov.GetPort(), prov.GetUser(), prov.GetSecret()}
+	return nil
+}
+
+// Alert sends the notification on slack.
+func (a *Alerter) Alert(ctx context.Context, metrics []checker.Metric, amap map[string]alerter.Alert) error {
+	for i := range metrics {
+		metric := metrics[i]
+		alt, ok := amap[metric.GetCheckID()]
+		if !ok {
+			continue
+		}
+
+		if err := a.alert(ctx, metric, alt); err != nil {
+			a.log.Errorf("check %s: %v", metric.GetCheckID(), err)
+			continue
+		}
+	}
+
+	return nil
+}
+
+// alert sends an individual notification.
+func (a *Alerter) alert(ctx context.Context, metric checker.Metric, alt alerter.Alert) error {
+	var msg string
+	if metric.IsSuccessful() {
+		msg = fmt.Sprintf("%s is back up", metric.GetCheckName())
+	} else {
+		msg = fmt.Sprintf("%s is down", metric.GetCheckName())
+		if metric.IsTimeout() {
+			msg = fmt.Sprintf("%s: timeout", metric.GetCheckName())
+		}
+	}
+
+	// Receiver's data
+	to := alt.GetTarget()
+
+	// Set E-mail
+	m := gomail.NewMessage()
+	m.SetHeader("From", a.sender.User)
+	m.SetHeader("To", to)
+	m.SetHeader("Subject", "Pinger Alert: "+msg)
+	m.SetBody("text/plain", msg)
+
+	// Settings for SMTP server
+	d := gomail.NewDialer(a.sender.Host, int(a.sender.Port), a.sender.User, a.sender.Secret)
+
+	// Sending E-Mail
+	if err := d.DialAndSend(m); err != nil {
+		return fmt.Errorf("could not send request: %v", err)
+	}
+
+	return nil
+}
+
+// Interface guard.
+var _ alerter.Alerter = (*Alerter)(nil)

pkg/alerter/mail/doc.go

@@ -0,0 +1,6 @@
+// Copyright (c) 2020 SDSLabs
+// Use of this source code is governed by an MIT license
+// details of which can be found in the LICENSE file.
+
+// Package mail implements the mail alerter.
+package mail

pkg/components/agent/alerter.go

@@ -7,5 +7,6 @@ package agent
 import (
 	// Register all the metrics alerters here.
 	_ "github.com/sdslabs/pinger/pkg/alerter/discord"
+	_ "github.com/sdslabs/pinger/pkg/alerter/mail"
 	_ "github.com/sdslabs/pinger/pkg/alerter/slack"
 )