From f03c45406cae0e5dd519068630efe9cb1cb5b762 Mon Sep 17 00:00:00 2001
From: Filippo Giunchedi <filippo@wikimedia.org>
Date: Wed, 25 Nov 2020 11:45:40 +0100
Subject: [PATCH] Make alert channel size configurable (and bigger)

Signed-off-by: Filippo Giunchedi <filippo@wikimedia.org>
---
 README.md      |  3 +++
 config.go      | 56 ++++++++++++++++++++++++++------------------------
 config_test.go | 23 +++++++++++----------
 main.go        |  2 +-
 4 files changed, 45 insertions(+), 39 deletions(-)

diff --git a/README.md b/README.md
index c504f93..dedd17a 100644
--- a/README.md
+++ b/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):
diff --git a/config.go b/config.go
index e554a82..0fa2fad 100644
--- a/config.go
+++ b/config.go
@@ -31,37 +31,39 @@ type IRCChannel struct {
 }
 
 type Config struct {
-	HTTPHost     string       `yaml:"http_host"`
-	HTTPPort     int          `yaml:"http_port"`
-	IRCNick      string       `yaml:"irc_nickname"`
-	IRCNickPass  string       `yaml:"irc_nickname_password"`
-	IRCRealName  string       `yaml:"irc_realname"`
-	IRCHost      string       `yaml:"irc_host"`
-	IRCPort      int          `yaml:"irc_port"`
-	IRCHostPass  string       `yaml:"irc_host_password"`
-	IRCUseSSL    bool         `yaml:"irc_use_ssl"`
-	IRCVerifySSL bool         `yaml:"irc_verify_ssl"`
-	IRCChannels  []IRCChannel `yaml:"irc_channels"`
-	MsgTemplate  string       `yaml:"msg_template"`
-	MsgOnce      bool         `yaml:"msg_once_per_alert_group"`
-	UsePrivmsg   bool         `yaml:"use_privmsg"`
+	HTTPHost        string       `yaml:"http_host"`
+	HTTPPort        int          `yaml:"http_port"`
+	IRCNick         string       `yaml:"irc_nickname"`
+	IRCNickPass     string       `yaml:"irc_nickname_password"`
+	IRCRealName     string       `yaml:"irc_realname"`
+	IRCHost         string       `yaml:"irc_host"`
+	IRCPort         int          `yaml:"irc_port"`
+	IRCHostPass     string       `yaml:"irc_host_password"`
+	IRCUseSSL       bool         `yaml:"irc_use_ssl"`
+	IRCVerifySSL    bool         `yaml:"irc_verify_ssl"`
+	IRCChannels     []IRCChannel `yaml:"irc_channels"`
+	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) {
 	config := &Config{
-		HTTPHost:     "localhost",
-		HTTPPort:     8000,
-		IRCNick:      "alertmanager-irc-relay",
-		IRCNickPass:  "",
-		IRCRealName:  "Alertmanager IRC Relay",
-		IRCHost:      "example.com",
-		IRCPort:      7000,
-		IRCHostPass:  "",
-		IRCUseSSL:    true,
-		IRCVerifySSL: true,
-		IRCChannels:  []IRCChannel{},
-		MsgOnce:      false,
-		UsePrivmsg:   false,
+		HTTPHost:        "localhost",
+		HTTPPort:        8000,
+		IRCNick:         "alertmanager-irc-relay",
+		IRCNickPass:     "",
+		IRCRealName:     "Alertmanager IRC Relay",
+		IRCHost:         "example.com",
+		IRCPort:         7000,
+		IRCHostPass:     "",
+		IRCUseSSL:       true,
+		IRCVerifySSL:    true,
+		IRCChannels:     []IRCChannel{},
+		MsgOnce:         false,
+		UsePrivmsg:      false,
+		AlertBufferSize: 2048,
 	}
 
 	if configFile != "" {
diff --git a/config_test.go b/config_test.go
index a029c37..486d09c 100644
--- a/config_test.go
+++ b/config_test.go
@@ -35,17 +35,18 @@ func TestNoConfig(t *testing.T) {
 
 func TestLoadGoodConfig(t *testing.T) {
 	expectedConfig := &Config{
-		HTTPHost:    "test.web",
-		HTTPPort:    8888,
-		IRCNick:     "foo",
-		IRCHost:     "irc.example.com",
-		IRCPort:     1234,
-		IRCHostPass: "hostsecret",
-		IRCUseSSL:   true,
-		IRCChannels: []IRCChannel{IRCChannel{Name: "#foobar"}},
-		MsgTemplate: defaultMsgTemplate,
-		MsgOnce:     false,
-		UsePrivmsg:  false,
+		HTTPHost:        "test.web",
+		HTTPPort:        8888,
+		IRCNick:         "foo",
+		IRCHost:         "irc.example.com",
+		IRCPort:         1234,
+		IRCHostPass:     "hostsecret",
+		IRCUseSSL:       true,
+		IRCChannels:     []IRCChannel{IRCChannel{Name: "#foobar"}},
+		MsgTemplate:     defaultMsgTemplate,
+		MsgOnce:         false,
+		UsePrivmsg:      false,
+		AlertBufferSize: 666,
 	}
 	expectedData, err := yaml.Marshal(expectedConfig)
 	if err != nil {
diff --git a/main.go b/main.go
index a4e1f82..d198042 100644
--- a/main.go
+++ b/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 {