cleanup

Author: amnonbc

README.md

@@ -2,3 +2,28 @@
 switch cloudflare FW to under_attack mode when server load is high
 
 [![Go](https://github.com/amnonbc/underattack/actions/workflows/go2.yml/badge.svg)](https://github.com/amnonbc/underattack/actions/workflows/go2.yml)
+
+This runs on a web host which sits behind cloudflare.
+
+It is run using a cron like
+
+```
+*/5 * * * * ${HOME}/bin/underattack -config ${HOME}/etc/underatttack.conf -default_level high >> ${HOME}/logs/underattack.log 2>&1
+```
+
+It checks the server's load, free memory and tries to connect to the db.
+If the load is too high, the free memory is too low, or if it can't connect to the db,
+then it sets CF into under-attack mode, which massively reduces bot traffic which usually allows server resources to recover.
+Once the server has recovered, then it turns off under-attack mode.
+
+The config file looks like this:
+
+```json
+{
+	"domain": "mydomain.com",
+	"apiKey": "cfApiKeyWithZoneZoneReadAmdZoneSecuritySet",
+	"DbName": "nameOfDb",
+	"DbUser": "NameOfDbUser",
+	"DbPassword": "dbUserPassword"
+}
+```

checkdb.go

@@ -6,9 +6,9 @@ import (
 	_ "github.com/go-sql-driver/mysql"
 )
 
-func checkDb(conf Config) error {
+func (a *app) checkDb() error {
 	db, err := sql.Open("mysql", fmt.Sprintf("%s:%s@tcp(127.0.0.1:3306)/%s",
-		conf.DbUser, conf.DbPassword, conf.DbName))
+		a.conf.DbUser, a.conf.DbPassword, a.conf.DbName))
 	if err != nil {
 		return err
 	}

under.go

@@ -24,15 +24,19 @@ type Config struct {
 	DbPassword string
 }
 
-var config Config
+type app struct {
+	conf   Config
+	api    *cloudflare.API
+	zoneId string
+}
 
-func loadConfig(fn string) error {
+func (a *app) loadConfig(fn string) error {
 	f, err := os.Open(fn)
 	if err != nil {
 		return err
 	}
 	defer f.Close()
-	return json.NewDecoder(f).Decode(&config)
+	return json.NewDecoder(f).Decode(&a.conf)
 }
 
 func loadAvg(text string) ([]float64, error) {
@@ -54,25 +58,27 @@ func loadAvg(text string) ([]float64, error) {
 	return res, nil
 }
 
-// setSecurityLevel sets the security level. value must be one of
-// off, essentially_off, low, medium, high, under_attack.
-func setSecurityLevel(value string) error {
-	api, err := cloudflare.NewWithAPIToken(config.ApiKey)
-	if err != nil {
-		return err
-	}
-	zoneID, err := api.ZoneIDByName(config.Domain)
+func (a *app) init() error {
+	var err error
+	a.api, err = cloudflare.NewWithAPIToken(a.conf.ApiKey)
 	if err != nil {
 		return err
 	}
+	a.zoneId, err = a.api.ZoneIDByName(a.conf.Domain)
+	return err
+}
 
-	currentLevel, err := currentLevel(api, zoneID)
+// setSecurityLevel sets the security level. value must be one of
+// off, essentially_off, low, medium, high, under_attack.
+// If the cf security is already at the reauested level, then do nothing.
+func (a *app) setSecurityLevel(value string) error {
+	currentLevel, err := a.currentLevel()
 	if currentLevel == value {
 		return nil
 	}
 
 	log.Println("setting security level to", value)
-	_, err = api.UpdateZoneSettings(context.TODO(), zoneID, []cloudflare.ZoneSetting{
+	_, err = a.api.UpdateZoneSettings(context.TODO(), a.zoneId, []cloudflare.ZoneSetting{
 		{
 			ID:    securityLevel,
 			Value: value,
@@ -81,15 +87,15 @@ func setSecurityLevel(value string) error {
 	return err
 }
 
-func mustSetSecurityLevel(value string) {
-	err := setSecurityLevel(value)
+func (a *app) mustSetSecurityLevel(value string) {
+	err := a.setSecurityLevel(value)
 	if err != nil {
 		log.Fatalln(err)
 	}
 }
 
-func currentLevel(api *cloudflare.API, zoneID string) (string, error) {
-	settings, err := api.ZoneSettings(context.TODO(), zoneID)
+func (a *app) currentLevel() (string, error) {
+	settings, err := a.api.ZoneSettings(context.TODO(), a.zoneId)
 	if err != nil {
 		return "", err
 	}
@@ -114,7 +120,13 @@ func main() {
 	if err != nil {
 		log.Fatalln(err)
 	}
-	err = loadConfig(*cf)
+	var a app
+	err = a.loadConfig(*cf)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	err = a.init()
 	if err != nil {
 		log.Fatalln(err)
 	}
@@ -131,23 +143,23 @@ func main() {
 	log.Println("freeMem", humanize.Bytes(freeMem), "load", la)
 	if freeMem < mb {
 		log.Println("free memory is below", *minBytesStr)
-		mustSetSecurityLevel("under_attack")
+		a.mustSetSecurityLevel("under_attack")
 		return
 	}
-	err = checkDb(config)
+	err = a.checkDb()
 	if err != nil {
 		log.Println("checkDb returned", err)
-		mustSetSecurityLevel("under_attack")
+		a.mustSetSecurityLevel("under_attack")
 		return
 	}
 
 	if la[0] >= *maxLoad {
 		log.Println("Load average is", la, "setting level to under_attack")
-		mustSetSecurityLevel("under_attack")
+		a.mustSetSecurityLevel("under_attack")
 		return
 	}
 	if la[0] < *minLoad && la[1] < *minLoad && la[2] < *minLoad {
-		mustSetSecurityLevel(*defaultSecurityLevel)
+		a.mustSetSecurityLevel(*defaultSecurityLevel)
 		return
 	}
 }