cherrypick notification changes from #450 (#745)

cmd/root.go

@@ -34,15 +34,20 @@ var (
 	scope          string
 )
 
-var rootCmd = &cobra.Command{
+var rootCmd = NewRootCommand()
-	Use:   "watchtower",
+
-	Short: "Automatically updates running Docker containers",
+// NewRootCommand creates the root command for watchtower
-	Long: `
+func NewRootCommand() *cobra.Command {
-Watchtower automatically updates running Docker containers whenever a new image is released.
+	return &cobra.Command{
-More information available at https://github.com/containrrr/watchtower/.
+		Use:   "watchtower",
-`,
+		Short: "Automatically updates running Docker containers",
-	Run:    Run,
+		Long: `
-	PreRun: PreRun,
+	Watchtower automatically updates running Docker containers whenever a new image is released.
+	More information available at https://github.com/containrrr/watchtower/.
+	`,
+		Run:    Run,
+		PreRun: PreRun,
+	}
 }
 
 func init() {

pkg/notifications/email.go

@@ -1,29 +1,22 @@
 package notifications
 
 import (
-	"encoding/base64"
-	"fmt"
-	"github.com/spf13/cobra"
-	"net/smtp"
 	"os"
-	"strings"
 	"time"
 
+	"github.com/spf13/cobra"
+
+	shoutrrrSmtp "github.com/containrrr/shoutrrr/pkg/services/smtp"
 	t "github.com/containrrr/watchtower/pkg/types"
 	log "github.com/sirupsen/logrus"
-	"strconv"
 )
 
 const (
 	emailType = "email"
 )
 
-// Implements Notifier, logrus.Hook
-// The default logrus email integration would have several issues:
-// - It would send one email per log output
-// - It would only send errors
-// We work around that by holding on to log entries until the update cycle is done.
 type emailTypeNotifier struct {
+	url                                string
 	From, To                           string
 	Server, User, Password, SubjectTag string
 	Port                               int
@@ -33,7 +26,12 @@ type emailTypeNotifier struct {
 	delay                              time.Duration
 }
 
-func newEmailNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifier {
+// NewEmailNotifier is a factory method creating a new email notifier instance
+func NewEmailNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.ConvertableNotifier {
+	return newEmailNotifier(c, acceptedLogLevels)
+}
+
+func newEmailNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.ConvertableNotifier {
 	flags := c.PersistentFlags()
 
 	from, _ := flags.GetString("notification-email-from")
@@ -47,6 +45,7 @@ func newEmailNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifie
 	subjecttag, _ := flags.GetString("notification-email-subjecttag")
 
 	n := &emailTypeNotifier{
+		entries:       []*log.Entry{},
 		From:          from,
 		To:            to,
 		Server:        server,
@@ -59,12 +58,33 @@ func newEmailNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifie
 		SubjectTag:    subjecttag,
 	}
 
-	log.AddHook(n)
-
 	return n
 }
 
-func (e *emailTypeNotifier) buildMessage(entries []*log.Entry) []byte {
+func (e *emailTypeNotifier) GetURL() string {
+	conf := &shoutrrrSmtp.Config{
+		FromAddress: e.From,
+		FromName:    "Watchtower",
+		ToAddresses: []string{e.To},
+		Port:        uint16(e.Port),
+		Host:        e.Server,
+		Subject:     e.getSubject(),
+		Username:    e.User,
+		Password:    e.Password,
+		UseStartTLS: true,
+		UseHTML:     false,
+	}
+
+	if len(e.User) > 0 {
+		conf.Set("auth", "Plain")
+	} else {
+		conf.Set("auth", "None")
+	}
+
+	return conf.GetURL().String()
+}
+
+func (e *emailTypeNotifier) getSubject() string {
 	var emailSubject string
 
 	if e.SubjectTag == "" {
@@ -75,83 +95,13 @@ func (e *emailTypeNotifier) buildMessage(entries []*log.Entry) []byte {
 	if hostname, err := os.Hostname(); err == nil {
 		emailSubject += " on " + hostname
 	}
-	body := ""
+	return emailSubject
-	for _, entry := range entries {
-		body += entry.Time.Format("2006-01-02 15:04:05") + " (" + entry.Level.String() + "): " + entry.Message + "\r\n"
-		// We don't use fields in watchtower, so don't bother sending them.
-	}
-
-	t := time.Now()
-
-	header := make(map[string]string)
-	header["From"] = e.From
-	header["To"] = e.To
-	header["Subject"] = emailSubject
-	header["Date"] = t.Format(time.RFC1123Z)
-	header["MIME-Version"] = "1.0"
-	header["Content-Type"] = "text/plain; charset=\"utf-8\""
-	header["Content-Transfer-Encoding"] = "base64"
-
-	message := ""
-	for k, v := range header {
-		message += fmt.Sprintf("%s: %s\r\n", k, v)
-	}
-
-	encodedBody := base64.StdEncoding.EncodeToString([]byte(body))
-	//RFC 2045 base64 encoding demands line no longer than 76 characters.
-	for _, line := range SplitSubN(encodedBody, 76) {
-		message += "\r\n" + line
-	}
-
-	return []byte(message)
 }
 
-func (e *emailTypeNotifier) sendEntries(entries []*log.Entry) {
+// TODO: Delete these once all notifiers have been converted to shoutrrr
-	// Do the sending in a separate goroutine so we don't block the main process.
+func (e *emailTypeNotifier) StartNotification()          {}
-	msg := e.buildMessage(entries)
+func (e *emailTypeNotifier) SendNotification()           {}
-	go func() {
+func (e *emailTypeNotifier) Levels() []log.Level         { return nil }
-		if e.delay > 0 {
+func (e *emailTypeNotifier) Fire(entry *log.Entry) error { return nil }
-			time.Sleep(e.delay)
-		}
-
-		var auth smtp.Auth
-		if e.User != "" {
-			auth = smtp.PlainAuth("", e.User, e.Password, e.Server)
-		}
-		err := SendMail(e.Server+":"+strconv.Itoa(e.Port), e.tlsSkipVerify, auth, e.From, strings.Split(e.To, ","), msg)
-		if err != nil {
-			// Use fmt so it doesn't trigger another email.
-			fmt.Println("Failed to send notification email: ", err)
-		}
-	}()
-}
-
-func (e *emailTypeNotifier) StartNotification() {
-	if e.entries == nil {
-		e.entries = make([]*log.Entry, 0, 10)
-	}
-}
-
-func (e *emailTypeNotifier) SendNotification() {
-	if e.entries == nil || len(e.entries) <= 0 {
-		return
-	}
-
-	e.sendEntries(e.entries)
-	e.entries = nil
-}
-
-func (e *emailTypeNotifier) Levels() []log.Level {
-	return e.logLevels
-}
-
-func (e *emailTypeNotifier) Fire(entry *log.Entry) error {
-	if e.entries != nil {
-		e.entries = append(e.entries, entry)
-	} else {
-		e.sendEntries([]*log.Entry{entry})
-	}
-	return nil
-}
 
 func (e *emailTypeNotifier) Close() {}

pkg/notifications/gotify.go

@@ -1,16 +1,13 @@
 package notifications
 
 import (
-	"bytes"
-	"crypto/tls"
-	"encoding/json"
-	"fmt"
-	"net/http"
 	"strings"
 
+	shoutrrrGotify "github.com/containrrr/shoutrrr/pkg/services/gotify"
 	t "github.com/containrrr/watchtower/pkg/types"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
 )
 
 const (
@@ -24,10 +21,40 @@ type gotifyTypeNotifier struct {
 	logLevels                []log.Level
 }
 
-func newGotifyNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifier {
+// NewGotifyNotifier is a factory method creating a new gotify notifier instance
+func NewGotifyNotifier(c *cobra.Command, levels []log.Level) t.ConvertableNotifier {
+	return newGotifyNotifier(c, levels)
+}
+
+func newGotifyNotifier(c *cobra.Command, levels []log.Level) t.ConvertableNotifier {
 	flags := c.PersistentFlags()
 
+	url := getGotifyURL(flags)
+	token := getGotifyToken(flags)
+
+	skipVerify, _ := flags.GetBool("notification-gotify-tls-skip-verify")
+
+	n := &gotifyTypeNotifier{
+		gotifyURL:                url,
+		gotifyAppToken:           token,
+		gotifyInsecureSkipVerify: skipVerify,
+		logLevels:                levels,
+	}
+
+	return n
+}
+
+func getGotifyToken(flags *pflag.FlagSet) string {
+	gotifyToken, _ := flags.GetString("notification-gotify-token")
+	if len(gotifyToken) < 1 {
+		log.Fatal("Required argument --notification-gotify-token(cli) or WATCHTOWER_NOTIFICATION_GOTIFY_TOKEN(env) is empty.")
+	}
+	return gotifyToken
+}
+
+func getGotifyURL(flags *pflag.FlagSet) string {
 	gotifyURL, _ := flags.GetString("notification-gotify-url")
+
 	if len(gotifyURL) < 1 {
 		log.Fatal("Required argument --notification-gotify-url(cli) or WATCHTOWER_NOTIFICATION_GOTIFY_URL(env) is empty.")
 	} else if !(strings.HasPrefix(gotifyURL, "http://") || strings.HasPrefix(gotifyURL, "https://")) {
@@ -36,82 +63,29 @@ func newGotifyNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifi
 		log.Warn("Using an HTTP url for Gotify is insecure")
 	}
 
-	gotifyToken, _ := flags.GetString("notification-gotify-token")
+	return gotifyURL
-	if len(gotifyToken) < 1 {
-		log.Fatal("Required argument --notification-gotify-token(cli) or WATCHTOWER_NOTIFICATION_GOTIFY_TOKEN(env) is empty.")
-	}
-
-	gotifyInsecureSkipVerify, _ := flags.GetBool("notification-gotify-tls-skip-verify")
-
-	n := &gotifyTypeNotifier{
-		gotifyURL:                gotifyURL,
-		gotifyAppToken:           gotifyToken,
-		gotifyInsecureSkipVerify: gotifyInsecureSkipVerify,
-		logLevels:                acceptedLogLevels,
-	}
-
-	log.AddHook(n)
-
-	return n
 }
 
-func (n *gotifyTypeNotifier) StartNotification() {}
+func (n *gotifyTypeNotifier) GetURL() string {
-
-func (n *gotifyTypeNotifier) SendNotification() {}
-
-func (n *gotifyTypeNotifier) Close() {}
-
-func (n *gotifyTypeNotifier) Levels() []log.Level {
-	return n.logLevels
-}
-
-func (n *gotifyTypeNotifier) getURL() string {
 	url := n.gotifyURL
-	if !strings.HasSuffix(url, "/") {
+
-		url += "/"
+	if strings.HasPrefix(url, "https://") {
+		url = strings.TrimPrefix(url, "https://")
+	} else {
+		url = strings.TrimPrefix(url, "http://")
 	}
-	return url + "message?token=" + n.gotifyAppToken
+
+	url = strings.TrimSuffix(url, "/")
+
+	config := &shoutrrrGotify.Config{
+		Host:  url,
+		Token: n.gotifyAppToken,
+	}
+
+	return config.GetURL().String()
 }
 
-func (n *gotifyTypeNotifier) Fire(entry *log.Entry) error {
+func (n *gotifyTypeNotifier) StartNotification()  {}
-
+func (n *gotifyTypeNotifier) SendNotification()   {}
-	go func() {
+func (n *gotifyTypeNotifier) Close()              {}
-		jsonBody, err := json.Marshal(gotifyMessage{
+func (n *gotifyTypeNotifier) Levels() []log.Level { return nil }
-			Message:  "(" + entry.Level.String() + "): " + entry.Message,
-			Title:    "Watchtower",
-			Priority: 0,
-		})
-		if err != nil {
-			fmt.Println("Failed to create JSON body for Gotify notification: ", err)
-			return
-		}
-
-		// Explicitly define the client so we can set InsecureSkipVerify to the desired value.
-		client := &http.Client{
-			Transport: &http.Transport{
-				TLSClientConfig: &tls.Config{
-					InsecureSkipVerify: n.gotifyInsecureSkipVerify,
-				},
-			},
-		}
-		jsonBodyBuffer := bytes.NewBuffer([]byte(jsonBody))
-		resp, err := client.Post(n.getURL(), "application/json", jsonBodyBuffer)
-		if err != nil {
-			fmt.Println("Failed to send Gotify notification: ", err)
-			return
-		}
-		defer resp.Body.Close()
-
-		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
-			fmt.Printf("Gotify notification returned %d HTTP status code", resp.StatusCode)
-		}
-
-	}()
-	return nil
-}
-
-type gotifyMessage struct {
-	Message  string `json:"message"`
-	Title    string `json:"title"`
-	Priority int    `json:"priority"`
-}

pkg/notifications/msteams.go

@@ -1,15 +1,12 @@
 package notifications
 
 import (
-	"bytes"
+	"strings"
-	"encoding/json"
-	"fmt"
-	"github.com/spf13/cobra"
-	"net/http"
 
+	shoutrrrTeams "github.com/containrrr/shoutrrr/pkg/services/teams"
 	t "github.com/containrrr/watchtower/pkg/types"
 	log "github.com/sirupsen/logrus"
-	"io/ioutil"
+	"github.com/spf13/cobra"
 )
 
 const (
@@ -22,7 +19,12 @@ type msTeamsTypeNotifier struct {
 	data       bool
 }
 
-func newMsTeamsNotifier(cmd *cobra.Command, acceptedLogLevels []log.Level) t.Notifier {
+// NewMsTeamsNotifier is a factory method creating a new teams notifier instance
+func NewMsTeamsNotifier(cmd *cobra.Command, acceptedLogLevels []log.Level) t.ConvertableNotifier {
+	return newMsTeamsNotifier(cmd, acceptedLogLevels)
+}
+
+func newMsTeamsNotifier(cmd *cobra.Command, acceptedLogLevels []log.Level) t.ConvertableNotifier {
 
 	flags := cmd.PersistentFlags()
 
@@ -38,103 +40,29 @@ func newMsTeamsNotifier(cmd *cobra.Command, acceptedLogLevels []log.Level) t.Not
 		data:       withData,
 	}
 
-	log.AddHook(n)
-
 	return n
 }
 
-func (n *msTeamsTypeNotifier) StartNotification() {}
+func (n *msTeamsTypeNotifier) GetURL() string {
 
-func (n *msTeamsTypeNotifier) SendNotification() {}
+	baseURL := "https://outlook.office.com/webhook/"
 
-func (n *msTeamsTypeNotifier) Close() {}
+	path := strings.Replace(n.webHookURL, baseURL, "", 1)
+	rawToken := strings.Replace(path, "/IncomingWebhook", "", 1)
+	token := strings.Split(rawToken, "/")
+	config := &shoutrrrTeams.Config{
+		Token: shoutrrrTeams.Token{
+			A: token[0],
+			B: token[1],
+			C: token[2],
+		},
+	}
 
-func (n *msTeamsTypeNotifier) Levels() []log.Level {
+	return config.GetURL().String()
-	return n.levels
 }
 
-func (n *msTeamsTypeNotifier) Fire(entry *log.Entry) error {
+func (n *msTeamsTypeNotifier) StartNotification()          {}
-
+func (n *msTeamsTypeNotifier) SendNotification()           {}
-	message := "(" + entry.Level.String() + "): " + entry.Message
+func (n *msTeamsTypeNotifier) Close()                      {}
-
+func (n *msTeamsTypeNotifier) Levels() []log.Level         { return nil }
-	go func() {
+func (n *msTeamsTypeNotifier) Fire(entry *log.Entry) error { return nil }
-		webHookBody := messageCard{
-			CardType: "MessageCard",
-			Context:  "http://schema.org/extensions",
-			Markdown: true,
-			Text:     message,
-		}
-
-		if n.data && entry.Data != nil && len(entry.Data) > 0 {
-			section := messageCardSection{
-				Facts: make([]messageCardSectionFact, len(entry.Data)),
-				Text:  "",
-			}
-
-			index := 0
-			for k, v := range entry.Data {
-				section.Facts[index] = messageCardSectionFact{
-					Name:  k,
-					Value: fmt.Sprint(v),
-				}
-				index++
-			}
-
-			webHookBody.Sections = []messageCardSection{section}
-		}
-
-		jsonBody, err := json.Marshal(webHookBody)
-		if err != nil {
-			fmt.Println("Failed to build JSON body for MSTeams notificattion: ", err)
-			return
-		}
-
-		resp, err := http.Post(n.webHookURL, "application/json", bytes.NewBuffer([]byte(jsonBody)))
-		if err != nil {
-			fmt.Println("Failed to send MSTeams notificattion: ", err)
-		}
-
-		defer resp.Body.Close()
-
-		if resp.StatusCode < 200 || resp.StatusCode > 299 {
-			fmt.Println("Failed to send MSTeams notificattion. HTTP RESPONSE STATUS: ", resp.StatusCode)
-			if resp.Body != nil {
-				bodyBytes, err := ioutil.ReadAll(resp.Body)
-				if err == nil {
-					bodyString := string(bodyBytes)
-					fmt.Println(bodyString)
-				}
-			}
-		}
-	}()
-
-	return nil
-}
-
-type messageCard struct {
-	CardType      string               `json:"@type"`
-	Context       string               `json:"@context"`
-	CorrelationID string               `json:"correlationId,omitempty"`
-	ThemeColor    string               `json:"themeColor,omitempty"`
-	Summary       string               `json:"summary,omitempty"`
-	Title         string               `json:"title,omitempty"`
-	Text          string               `json:"text,omitempty"`
-	Markdown      bool                 `json:"markdown,bool"`
-	Sections      []messageCardSection `json:"sections,omitempty"`
-}
-
-type messageCardSection struct {
-	Title            string                   `json:"title,omitempty"`
-	Text             string                   `json:"text,omitempty"`
-	ActivityTitle    string                   `json:"activityTitle,omitempty"`
-	ActivitySubtitle string                   `json:"activitySubtitle,omitempty"`
-	ActivityImage    string                   `json:"activityImage,omitempty"`
-	ActivityText     string                   `json:"activityText,omitempty"`
-	HeroImage        string                   `json:"heroImage,omitempty"`
-	Facts            []messageCardSectionFact `json:"facts,omitempty"`
-}
-
-type messageCardSectionFact struct {
-	Name  string `json:"name,omitempty"`
-	Value string `json:"value,omitempty"`
-}

pkg/notifications/notifier.go

@@ -31,26 +31,48 @@ func NewNotifier(c *cobra.Command) *Notifier {
 	if err != nil {
 		log.WithField("could not read notifications argument", log.Fields{"Error": err}).Fatal()
 	}
+
+	n.types = n.GetNotificationTypes(c, acceptedLogLevels, types)
+
+	return n
+}
+
+// GetNotificationTypes produces an array of notifiers from a list of types
+func (n *Notifier) GetNotificationTypes(cmd *cobra.Command, levels []log.Level, types []string) []ty.Notifier {
+	output := make([]ty.Notifier, 0)
+
 	for _, t := range types {
-		var tn ty.Notifier
+
+		if t == shoutrrrType {
+			output = append(output, newShoutrrrNotifier(cmd, levels))
+			continue
+		}
+
+		var legacyNotifier ty.ConvertableNotifier
+
 		switch t {
 		case emailType:
-			tn = newEmailNotifier(c, acceptedLogLevels)
+			legacyNotifier = newEmailNotifier(cmd, []log.Level{})
 		case slackType:
-			tn = newSlackNotifier(c, acceptedLogLevels)
+			legacyNotifier = newSlackNotifier(cmd, []log.Level{})
 		case msTeamsType:
-			tn = newMsTeamsNotifier(c, acceptedLogLevels)
+			legacyNotifier = newMsTeamsNotifier(cmd, levels)
 		case gotifyType:
-			tn = newGotifyNotifier(c, acceptedLogLevels)
+			legacyNotifier = newGotifyNotifier(cmd, []log.Level{})
-		case shoutrrrType:
-			tn = newShoutrrrNotifier(c, acceptedLogLevels)
 		default:
 			log.Fatalf("Unknown notification type %q", t)
 		}
-		n.types = append(n.types, tn)
+
+		notifier := newShoutrrrNotifierFromURL(
+			cmd,
+			legacyNotifier.GetURL(),
+			levels,
+		)
+
+		output = append(output, notifier)
 	}
 
-	return n
+	return output
 }
 
 // StartNotification starts a log batch. Notifications will be accumulated after this point and only sent when SendNotification() is called.

pkg/notifications/notifier_test.go

@@ -0,0 +1,163 @@
+package notifications_test
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/containrrr/watchtower/cmd"
+	"github.com/containrrr/watchtower/internal/flags"
+	"github.com/containrrr/watchtower/pkg/notifications"
+	"github.com/containrrr/watchtower/pkg/types"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+func TestActions(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Notifier Suite")
+}
+
+var _ = Describe("notifications", func() {
+	// TODO: Either, we delete this test or we need to pass it valid URLs in the cobra command.
+	// ---
+	// When("getting notifiers from a types array", func() {
+	// 	It("should return the same amount of notifiers a string entries", func() {
+
+	// 		notifier := &notifications.Notifier{}
+	// 		notifiers := notifier.GetNotificationTypes(&cobra.Command{}, []log.Level{}, []string{"slack", "email"})
+	// 		Expect(len(notifiers)).To(Equal(2))
+	// 	})
+	// })
+	Describe("the slack notifier", func() {
+		When("converting a slack service config into a shoutrrr url", func() {
+			builderFn := notifications.NewSlackNotifier
+
+			It("should return the expected URL", func() {
+
+				username := "containrrrbot"
+				tokenA := "aaa"
+				tokenB := "bbb"
+				tokenC := "ccc"
+
+				password := fmt.Sprintf("%s-%s-%s", tokenA, tokenB, tokenC)
+				hookURL := fmt.Sprintf("https://hooks.slack.com/services/%s/%s/%s", tokenA, tokenB, tokenC)
+				expectedOutput := fmt.Sprintf("slack://%s:%s@%s/%s/%s", username, password, tokenA, tokenB, tokenC)
+
+				args := []string{
+					"--notification-slack-hook-url",
+					hookURL,
+					"--notification-slack-identifier",
+					username,
+				}
+
+				testURL(builderFn, args, expectedOutput)
+			})
+		})
+	})
+
+	Describe("the gotify notifier", func() {
+		When("converting a gotify service config into a shoutrrr url", func() {
+			builderFn := notifications.NewGotifyNotifier
+
+			It("should return the expected URL", func() {
+				token := "aaa"
+				host := "shoutrrr.local"
+
+				expectedOutput := fmt.Sprintf("gotify://%s/%s", host, token)
+
+				args := []string{
+					"--notification-gotify-url",
+					fmt.Sprintf("https://%s", host),
+					"--notification-gotify-token",
+					token,
+				}
+
+				testURL(builderFn, args, expectedOutput)
+			})
+		})
+	})
+
+	Describe("the teams notifier", func() {
+		When("converting a teams service config into a shoutrrr url", func() {
+			builderFn := notifications.NewMsTeamsNotifier
+
+			It("should return the expected URL", func() {
+
+				tokenA := "aaa"
+				tokenB := "bbb"
+				tokenC := "ccc"
+
+				hookURL := fmt.Sprintf("https://outlook.office.com/webhook/%s/IncomingWebhook/%s/%s", tokenA, tokenB, tokenC)
+				expectedOutput := fmt.Sprintf("teams://%s:%s@%s", tokenA, tokenB, tokenC)
+
+				args := []string{
+					"--notification-msteams-hook",
+					hookURL,
+				}
+
+				testURL(builderFn, args, expectedOutput)
+			})
+		})
+	})
+
+	Describe("the email notifier", func() {
+
+		builderFn := notifications.NewEmailNotifier
+
+		When("converting an email service config into a shoutrrr url", func() {
+			It("should set the from address in the URL", func() {
+				fromAddress := "lala@example.com"
+				expectedOutput := buildExpectedURL("", "", "", 25, fromAddress, "", "None")
+				args := []string{
+					"--notification-email-from",
+					fromAddress,
+				}
+				testURL(builderFn, args, expectedOutput)
+			})
+
+			It("should return the expected URL", func() {
+
+				fromAddress := "sender@example.com"
+				toAddress := "receiver@example.com"
+				expectedOutput := buildExpectedURL("", "", "", 25, fromAddress, toAddress, "None")
+
+				args := []string{
+					"--notification-email-from",
+					fromAddress,
+					"--notification-email-to",
+					toAddress,
+				}
+
+				testURL(builderFn, args, expectedOutput)
+			})
+		})
+	})
+})
+
+func buildExpectedURL(username string, password string, host string, port int, from string, to string, auth string) string {
+	hostname, err := os.Hostname()
+	Expect(err).NotTo(HaveOccurred())
+
+	subject := fmt.Sprintf("Watchtower updates on %s", hostname)
+
+	var template = "smtp://%s:%s@%s:%d/?fromAddress=%s&fromName=Watchtower&toAddresses=%s&auth=%s&subject=%s&startTls=Yes&useHTML=No"
+	return fmt.Sprintf(template, username, password, host, port, from, to, auth, subject)
+}
+
+type builderFn = func(c *cobra.Command, acceptedLogLevels []log.Level) types.ConvertableNotifier
+
+func testURL(builder builderFn, args []string, expectedURL string) {
+
+	command := cmd.NewRootCommand()
+	flags.RegisterNotificationFlags(command)
+	command.ParseFlags(args)
+
+	notifier := builder(command, []log.Level{})
+	actualURL := notifier.GetURL()
+
+	Expect(actualURL).To(Equal(expectedURL))
+}

pkg/notifications/shoutrrr.go

@@ -35,8 +35,17 @@ type shoutrrrTypeNotifier struct {
 
 func newShoutrrrNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifier {
 	flags := c.PersistentFlags()
-
 	urls, _ := flags.GetStringArray("notification-url")
+	template := getShoutrrrTemplate(c)
+	return createSender(urls, acceptedLogLevels, template)
+}
+
+func newShoutrrrNotifierFromURL(c *cobra.Command, url string, levels []log.Level) t.Notifier {
+	template := getShoutrrrTemplate(c)
+	return createSender([]string{url}, levels, template)
+}
+
+func createSender(urls []string, levels []log.Level, template *template.Template) t.Notifier {
 	r, err := shoutrrr.CreateSender(urls...)
 	if err != nil {
 		log.Fatalf("Failed to initialize Shoutrrr notifications: %s\n", err.Error())
@@ -45,10 +54,10 @@ func newShoutrrrNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Noti
 	n := &shoutrrrTypeNotifier{
 		Urls:      urls,
 		Router:    r,
-		logLevels: acceptedLogLevels,
-		template:  getShoutrrrTemplate(c),
 		messages:  make(chan string, 1),
 		done:      make(chan bool),
+		logLevels: levels,
+		template:  template,
 	}
 
 	log.AddHook(n)

pkg/notifications/slack.go

@@ -1,6 +1,9 @@
 package notifications
 
 import (
+	"strings"
+
+	shoutrrrSlack "github.com/containrrr/shoutrrr/pkg/services/slack"
 	t "github.com/containrrr/watchtower/pkg/types"
 	"github.com/johntdyer/slackrus"
 	log "github.com/sirupsen/logrus"
@@ -15,7 +18,12 @@ type slackTypeNotifier struct {
 	slackrus.SlackrusHook
 }
 
-func newSlackNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifier {
+// NewSlackNotifier is a factory function used to generate new instance of the slack notifier type
+func NewSlackNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.ConvertableNotifier {
+	return newSlackNotifier(c, acceptedLogLevels)
+}
+
+func newSlackNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.ConvertableNotifier {
 	flags := c.PersistentFlags()
 
 	hookURL, _ := flags.GetString("notification-slack-hook-url")
@@ -23,7 +31,6 @@ func newSlackNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifie
 	channel, _ := flags.GetString("notification-slack-channel")
 	emoji, _ := flags.GetString("notification-slack-icon-emoji")
 	iconURL, _ := flags.GetString("notification-slack-icon-url")
-
 	n := &slackTypeNotifier{
 		SlackrusHook: slackrus.SlackrusHook{
 			HookURL:        hookURL,
@@ -34,12 +41,27 @@ func newSlackNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifie
 			AcceptedLevels: acceptedLogLevels,
 		},
 	}
-
-	log.AddHook(n)
 	return n
 }
 
-func (s *slackTypeNotifier) StartNotification() {}
+func (s *slackTypeNotifier) GetURL() string {
+	rawTokens := strings.Replace(s.HookURL, "https://hooks.slack.com/services/", "", 1)
+	tokens := strings.Split(rawTokens, "/")
+
+	conf := &shoutrrrSlack.Config{
+		BotName: s.Username,
+		Token: shoutrrrSlack.Token{
+			A: tokens[0],
+			B: tokens[1],
+			C: tokens[2],
+		},
+	}
+
+	return conf.GetURL().String()
+}
+
+func (s *slackTypeNotifier) StartNotification() {
+}
 
 func (s *slackTypeNotifier) SendNotification() {}
 

pkg/types/convertable_notifier.go

@@ -0,0 +1,7 @@
+package types
+
+// ConvertableNotifier is a notifier capable of creating a shoutrrr URL
+type ConvertableNotifier interface {
+	Notifier
+	GetURL() string
+}