Feature: Set optional webhook for received messages (#195)

README.md

@@ -37,6 +37,7 @@ Mailpit was originally **inspired** by MailHog which is now [no longer maintaine
 - Optional HTTPS for web UI ([see wiki](https://github.com/axllent/mailpit/wiki/HTTPS))
 - Optional basic authentication for web UI ([see wiki](https://github.com/axllent/mailpit/wiki/Basic-authentication))
 - A simple REST API ([see docs](docs/apiv1/README.md))
+- Optional webhook for received messages ([see docs](https://github.com/axllent/mailpit/wiki/Webhook))
 - Multi-architecture [Docker images](https://github.com/axllent/mailpit/wiki/Docker-images)
 
 

cmd/root.go

@@ -13,6 +13,7 @@ import (
 	"github.com/axllent/mailpit/internal/storage"
 	"github.com/axllent/mailpit/server"
 	"github.com/axllent/mailpit/server/smtpd"
+	"github.com/axllent/mailpit/server/webhook"
 	"github.com/spf13/cobra"
 )
 
@@ -105,6 +106,8 @@ func init() {
 
 	rootCmd.Flags().StringVar(&config.SMTPRelayConfigFile, "smtp-relay-config", config.SMTPRelayConfigFile, "SMTP configuration file to allow releasing messages")
 	rootCmd.Flags().BoolVar(&config.SMTPRelayAllIncoming, "smtp-relay-all", config.SMTPRelayAllIncoming, "Relay all incoming messages via external SMTP server (caution!)")
+	rootCmd.Flags().StringVar(&config.WebhookURL, "webhook-url", config.WebhookURL, "Send a webhook request for new messages")
+	rootCmd.Flags().IntVar(&webhook.RateLimit, "webhook-limit", webhook.RateLimit, "Limit webhook requests per second")
 
 	rootCmd.Flags().StringVarP(&config.SMTPCLITags, "tag", "t", config.SMTPCLITags, "Tag new messages matching filters")
 	rootCmd.Flags().BoolVarP(&logger.QuietLogging, "quiet", "q", logger.QuietLogging, "Quiet logging (errors only)")
@@ -169,6 +172,14 @@ func initConfigFromEnv() {
 		config.SMTPRelayAllIncoming = true
 	}
 
+	// Webhook
+	if len(os.Getenv("MP_WEBHOOK_URL")) > 0 {
+		config.WebhookURL = os.Getenv("MP_WEBHOOK_URL")
+	}
+	if len(os.Getenv("MP_WEBHOOK_LIMIT")) > 0 {
+		webhook.RateLimit, _ = strconv.Atoi(os.Getenv("MP_WEBHOOK_LIMIT"))
+	}
+
 	// Misc options
 	if len(os.Getenv("MP_WEBROOT")) > 0 {
 		config.Webroot = os.Getenv("MP_WEBROOT")

config/config.go

@@ -4,6 +4,7 @@ package config
 import (
 	"errors"
 	"fmt"
+	"net/url"
 	"os"
 	"path"
 	"path/filepath"
@@ -94,6 +95,9 @@ var (
 	// Use with extreme caution!
 	SMTPRelayAllIncoming = false
 
+	// WebhookURL for calling
+	WebhookURL string
+
 	// ContentSecurityPolicy for HTTP server - set via VerifyConfig()
 	ContentSecurityPolicy string
 
@@ -223,6 +227,10 @@ func VerifyConfig() error {
 	s := strings.TrimRight(path.Join("/", Webroot, "/"), "/") + "/"
 	Webroot = s
 
+	if WebhookURL != "" && !isValidURL(WebhookURL) {
+		return fmt.Errorf("Webhook URL does not appear to be a valid URL (%s)", WebhookURL)
+	}
+
 	SMTPTags = []AutoTag{}
 
 	if SMTPCLITags != "" {
@@ -349,3 +357,12 @@ func isDir(path string) bool {
 
 	return true
 }
+
+func isValidURL(s string) bool {
+	u, err := url.ParseRequestURI(s)
+	if err != nil {
+		return false
+	}
+
+	return strings.HasPrefix(u.Scheme, "http")
+}

go.mod

@@ -23,6 +23,7 @@ require (
 	github.com/vanng822/go-premailer v1.20.2
 	golang.org/x/net v0.17.0
 	golang.org/x/text v0.13.0
+	golang.org/x/time v0.3.0
 	gopkg.in/yaml.v3 v3.0.1
 	modernc.org/sqlite v1.26.0
 )

go.sum

@@ -192,6 +192,8 @@ golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/text v0.13.0 h1:ablQoSUd0tRdKxZewP80B+BaqeKJuVhuRxj/dkrun3k=
 golang.org/x/text v0.13.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
+golang.org/x/time v0.3.0 h1:rg5rLMjNzMS1RkNLzCG38eapWhnYLFYXDXj2gOlr8j4=
+golang.org/x/time v0.3.0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=

internal/storage/database.go

@@ -21,6 +21,7 @@ import (
 	"github.com/axllent/mailpit/config"
 	"github.com/axllent/mailpit/internal/logger"
 	"github.com/axllent/mailpit/internal/tools"
+	"github.com/axllent/mailpit/server/webhook"
 	"github.com/axllent/mailpit/server/websockets"
 	"github.com/google/uuid"
 	"github.com/jhillyerd/enmime"
@@ -234,6 +235,7 @@ func Store(body []byte) (string, error) {
 	c.Snippet = snippet
 
 	websockets.Broadcast("new", c)
+	webhook.Send(c)
 
 	dbLastAction = time.Now()
 

server/webhook/webhook.go

@@ -0,0 +1,72 @@
+// Package webhook will optionally call a preconfigured endpoint
+package webhook
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"time"
+
+	"github.com/axllent/mailpit/config"
+	"github.com/axllent/mailpit/internal/logger"
+	"golang.org/x/time/rate"
+)
+
+var (
+	// RateLimit is the minimum number of seconds between requests
+	RateLimit = 1
+
+	rl rate.Sometimes
+
+	rateLimiterSet bool
+)
+
+// Send will post the MessageSummary to a webhook (if configured)
+func Send(msg interface{}) {
+	if config.WebhookURL == "" {
+		return
+	}
+
+	if !rateLimiterSet {
+		if RateLimit > 0 {
+			rl = rate.Sometimes{Interval: time.Duration(RateLimit) * time.Second}
+		} else {
+			// run 1000 per second - ie: do not limit
+			rl = rate.Sometimes{First: 1000, Interval: time.Second}
+		}
+		rateLimiterSet = true
+	}
+
+	go func() {
+		rl.Do(func() {
+			b, err := json.Marshal(msg)
+			if err != nil {
+				logger.Log().Errorf("[webhook] invalid data: %s", err)
+				return
+			}
+
+			req, err := http.NewRequest("POST", config.WebhookURL, bytes.NewBuffer(b))
+			if err != nil {
+				logger.Log().Errorf("[webhook] error: %s", err)
+				return
+			}
+
+			req.Header.Set("User-Agent", "Mailpit/"+config.Version)
+			req.Header.Set("Content-Type", "application/json")
+
+			client := &http.Client{}
+			resp, err := client.Do(req)
+			if err != nil {
+				logger.Log().Errorf("[webhook] error sending data: %s", err)
+				return
+			}
+
+			if resp.StatusCode < 200 || resp.StatusCode > 299 {
+				logger.Log().Warningf("[webhook] %s returned a %d status", config.WebhookURL, resp.StatusCode)
+				return
+			}
+
+			defer resp.Body.Close()
+		})
+	}()
+}

server/websockets/hub.go

@@ -80,6 +80,7 @@ func Broadcast(t string, msg interface{}) {
 
 	if err != nil {
 		logger.Log().Errorf("[websocket] broadcast received invalid data: %s", err)
+		return
 	}
 
 	go func() { MessageHub.Broadcast <- b }()