Make alert channel size configurable (and bigger)

Signed-off-by: Filippo Giunchedi <filippo@wikimedia.org>

README.md

@@ -63,6 +63,9 @@ msg_template: "Alert {{ .Labels.alertname }} on {{ .Labels.instance }} is {{ .St
 # Note: When sending only one message per alert group the default
 # msg_template is set to
 # "Alert {{ .GroupLabels.alertname }} for {{ .GroupLabels.job }} is {{ .Status }}"
+
+# Set the internal buffer size for alerts received but not yet sent to IRC.
+alert_buffer_size: 2048
 ```
 
 Running the bot (assuming *$GOPATH* and *$PATH* are properly setup for go):

config.go

@@ -45,6 +45,7 @@ type Config struct {
 	MsgTemplate     string       `yaml:"msg_template"`
 	MsgOnce         bool         `yaml:"msg_once_per_alert_group"`
 	UsePrivmsg      bool         `yaml:"use_privmsg"`
+	AlertBufferSize int          `yaml:"alert_buffer_size"`
 }
 
 func LoadConfig(configFile string) (*Config, error) {
@@ -62,6 +63,7 @@ func LoadConfig(configFile string) (*Config, error) {
 		IRCChannels:     []IRCChannel{},
 		MsgOnce:         false,
 		UsePrivmsg:      false,
+		AlertBufferSize: 2048,
 	}
 
 	if configFile != "" {

config_test.go

@@ -46,6 +46,7 @@ func TestLoadGoodConfig(t *testing.T) {
 		MsgTemplate:     defaultMsgTemplate,
 		MsgOnce:         false,
 		UsePrivmsg:      false,
+		AlertBufferSize: 666,
 	}
 	expectedData, err := yaml.Marshal(expectedConfig)
 	if err != nil {

main.go

@@ -37,7 +37,7 @@ func main() {
 		return
 	}
 
-	alertMsgs := make(chan AlertMsg, 10)
+	alertMsgs := make(chan AlertMsg, config.AlertBufferSize)
 
 	ircNotifier, err := NewIRCNotifier(config, alertMsgs)
 	if err != nil {