Add config option to deliver alerts with PRIVMSG

Add `use_privmsg` config option to deliver alerts with PRIVMSG instead
of the default NOTICE.

This addresses a use case described in
https://github.com/google/alertmanager-irc-relay/pull/1 .

Signed-off-by: Luca Bigliardi <shammash@google.com>

README.md

@@ -48,6 +48,11 @@ irc_channels:
 # Send only one message when webhook data is received.
 # Note: By default a message is sent for each alert in the webhook data.
 msg_once_per_alert_group: no
+#
+# Use PRIVMSG instead of NOTICE (default) to send messages.
+# Note: Sending PRIVMSG from bots is bad practice, do not enable this unless
+# necessary (e.g. unless NOTICEs would weaken your channel moderation policies)
+use_privmsg: yes
 
 # Define how IRC messages should be formatted.
 #

config.go

@@ -41,6 +41,7 @@ type Config struct {
 	IRCChannels []IRCChannel `yaml:"irc_channels"`
 	MsgTemplate string       `yaml:"msg_template"`
 	MsgOnce     bool         `yaml:"msg_once_per_alert_group"`
+	UsePrivmsg  bool         `yaml:"use_privmsg"`
 }
 
 func LoadConfig(configFile string) (*Config, error) {
@@ -55,6 +56,7 @@ func LoadConfig(configFile string) (*Config, error) {
 		IRCUseSSL:   true,
 		IRCChannels: []IRCChannel{IRCChannel{Name: "#airtest"}},
 		MsgOnce:     false,
+		UsePrivmsg:  false,
 	}
 
 	if configFile != "" {

config_test.go

@@ -43,6 +43,7 @@ func TestLoadGoodConfig(t *testing.T) {
 		IRCChannels: []IRCChannel{IRCChannel{Name: "#foobar"}},
 		MsgTemplate: defaultMsgTemplate,
 		MsgOnce:     false,
+		UsePrivmsg:  false,
 	}
 	expectedData, err := yaml.Marshal(expectedConfig)
 	if err != nil {

irc.go

@@ -62,6 +62,8 @@ type IRCNotifier struct {
 	PreJoinChannels []IRCChannel
 	JoinedChannels  map[string]ChannelState
 
+	UsePrivmsg bool
+
 	NickservDelayWait time.Duration
 	BackoffCounter    Delayer
 }
@@ -94,6 +96,7 @@ func NewIRCNotifier(config *Config, alertMsgs chan AlertMsg) (*IRCNotifier, erro
 		sessionDownSignal: make(chan bool),
 		PreJoinChannels:   config.IRCChannels,
 		JoinedChannels:    make(map[string]ChannelState),
+		UsePrivmsg:        config.UsePrivmsg,
 		NickservDelayWait: nickservWaitSecs * time.Second,
 		BackoffCounter:    backoffCounter,
 	}
@@ -196,8 +199,13 @@ func (notifier *IRCNotifier) MaybeSendAlertMsg(alertMsg *AlertMsg) {
 		return
 	}
 	notifier.JoinChannel(&IRCChannel{Name: alertMsg.Channel})
+
+	if notifier.UsePrivmsg {
+		notifier.Client.Privmsg(alertMsg.Channel, alertMsg.Alert)
+	} else {
 		notifier.Client.Notice(alertMsg.Channel, alertMsg.Alert)
 	}
+}
 
 func (notifier *IRCNotifier) Run() {
 	keepGoing := true

irc_test.go

@@ -212,6 +212,7 @@ func makeTestIRCConfig(IRCPort int) *Config {
 			IRCChannel{Name: "#bar"},
 			IRCChannel{Name: "#baz"},
 		},
+		UsePrivmsg: false,
 	}
 }
 
@@ -321,6 +322,63 @@ func TestSendAlertOnPreJoinedChannel(t *testing.T) {
 	}
 }
 
+func TestUsePrivmsgToSendAlertOnPreJoinedChannel(t *testing.T) {
+	server, port := makeTestServer(t)
+	config := makeTestIRCConfig(port)
+	config.UsePrivmsg = true
+	notifier, alertMsgs := makeTestNotifier(t, config)
+
+	var testStep sync.WaitGroup
+
+	testChannel := "#foo"
+	testMessage := "test message"
+
+	// Send the alert after configured channels have joined, to ensure we
+	// check for no re-join attempt.
+	joinedHandler := func(conn *bufio.ReadWriter, line *irc.Line) error {
+		if line.Args[0] == testChannel {
+			testStep.Done()
+		}
+		return nil
+	}
+	server.SetHandler("JOIN", joinedHandler)
+
+	testStep.Add(1)
+	go notifier.Run()
+
+	testStep.Wait()
+
+	server.SetHandler("JOIN", nil)
+
+	privmsgHandler := func(conn *bufio.ReadWriter, line *irc.Line) error {
+		testStep.Done()
+		return nil
+	}
+	server.SetHandler("PRIVMSG", privmsgHandler)
+
+	testStep.Add(1)
+	alertMsgs <- AlertMsg{Channel: testChannel, Alert: testMessage}
+
+	testStep.Wait()
+
+	notifier.StopRunning <- true
+	server.Stop()
+
+	expectedCommands := []string{
+		"NICK foo",
+		"USER foo 12 * :",
+		"JOIN #foo",
+		"JOIN #bar",
+		"JOIN #baz",
+		"PRIVMSG #foo :test message",
+		"QUIT :see ya",
+	}
+
+	if !reflect.DeepEqual(expectedCommands, server.Log) {
+		t.Error("Alert not sent correctly. Received commands:\n", strings.Join(server.Log, "\n"))
+	}
+}
+
 func TestSendAlertAndJoinChannel(t *testing.T) {
 	server, port := makeTestServer(t)
 	config := makeTestIRCConfig(port)