Tables are now updated only if status of host changers

- Possibilité de régler le niveau de log (0,1,2) avec le flag -verbose (#2)

.gitlab-ci.yml

@@ -0,0 +1,28 @@
+# You can copy and paste this template into a new `.gitlab-ci.yml` file.
+# You should not add this template to an existing `.gitlab-ci.yml` file by using the `include:` keyword.
+#
+# To contribute improvements to CI/CD templates, please follow the Development guide at:
+# https://docs.gitlab.com/ee/development/cicd/templates.html
+# This specific template is located at:
+# https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Go.gitlab-ci.yml
+
+stages:
+  - test
+  - build
+
+format:
+  stage: test
+  script:
+    - go fmt $(go list ./... | grep -v /vendor/)
+    - go vet $(go list ./... | grep -v /vendor/)
+
+compile:
+  stage: build
+  script:
+    - mkdir -p mybinaries
+    - go build -o mybinaries ./...
+  artifacts:
+    paths:
+      - mybinaries
+
+

README.md

@@ -0,0 +1,32 @@
+HostChecker
+===========
+
+HostChecker est un outil très simpliste, qui teste la disponibilité de services distants (tcp, http, smtp) pour établir la disponibilité d'un serveur (host).
+
+En fonction du résultat du test, il ajoute  ou supprime le serveur (désigné par son IP) d'une table PF.
+
+L'outil est écrit spécifiquement pour répondre à un besoin précis.
+Sur des pare-feux réseau FreeBSD ou OpenBSD, PF (packet filter) permet de distribuer un traffic entrant vers un ou plusieurs serveurs `backends` en round-robin.
+
+Si l'un de ces serveurs est indisponible, PF ne peut le détecter et continue de distribuer du traffic vers ce backend, générant donc des erreurs. Il existe plusieurs moyens pour pallier à ce problème, dont l'utilisation d'un proxy applicatif sur le pare-feu lui-même ou l'utilisation d'IP virtuelles redondées sur les serveurs backends.
+
+HostChecker permet d'avoir une troisième solution, celle de gérer dynamiquement la liste des serveurs backends référencés dans une table PF.
+
+Configuration
+--------------
+
+La configuration se fait dans un seul fichier YAML qui décrit un ou plusieurs groupes de serveurs, les méthodes de test et les tables PF a mettre à jour.
+
+```
+cluster-web:
+  tables:
+    - cluster-web-hosts
+  hosts:
+    - 10.10.1.10
+    - 10.10.1.11
+  check:
+    - type: http
+    - port: 80
+    - interval: 5
+    - timeout: 2
+```

go.sum

@@ -0,0 +1,3 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

hostchecker.go

@@ -1,3 +1,18 @@
+/*
+Copyright 2023 Laurent Ulrich (laurentu@gmail.com)
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
 package main
 
 import "fmt"
@@ -14,6 +29,7 @@ import "errors"
 import "net"
 import "os/exec"
 import "flag"
+import "log/syslog"
 
 type Check struct {
 	Type     string `yaml:"type"`
@@ -32,13 +48,24 @@ type Group struct {
 	Check  Check    `yaml:"check"`
 }
 
+var verbose int
 
 func main() {
+	if verbose > 0 {
 		log.Println("Starting")
-
+	}
 	confFileName := flag.String("f", "/usr/local/etc/hostchecker.yaml", "YAML configuration file")
+	flag.IntVar(&verbose, "verbose", 0, "Set logs verbosity")
+	useSyslog := flag.Bool("syslog", false, "Send logs to syslog")
 	flag.Parse()
 
+	if *useSyslog == true {
+		syslogWriter, err := syslog.New(syslog.LOG_ERR, "hostchecker")
+		if err != nil {
+			log.Fatal("Error opening syslog #", err)
+		}
+		log.SetOutput(syslogWriter)
+	}
 	var waitGroup sync.WaitGroup
 
 	var conf map[string]Group
@@ -57,7 +84,9 @@ func main() {
 	}
 	stopChannel := make(chan bool)
 	for name, group := range conf {
+		if verbose > 0 {
 			log.Println("Checking group", name, group)
+		}
 		waitGroup.Add(1)
 		go checkGroup(name, group, &waitGroup, stopChannel)
 	}
@@ -67,17 +96,23 @@ func main() {
 	signal.Notify(exit, os.Interrupt)
 
 	s := <-exit
+	if verbose > 1 {
 		log.Println("Received signal", s)
+	}
+	if verbose > 0 {
 		log.Println("main closing stopChannel")
+	}
 	close(stopChannel)
 	waitGroup.Wait()
 }
 
 func checkGroup(name string, group Group, waitGroup *sync.WaitGroup, stopChannel chan bool) {
 	channels := make(map[string]chan int)
+  statusPerHost := make(map[string]int)
 	for _, host := range group.Hosts {
 		channel := make(chan int, 1)
 		channels[host] = channel
+    statusPerHost[host] = -1
 		waitGroup.Add(1)
 		go checkHost(channels[host], name, host, group.Check, waitGroup, stopChannel)
 	}
@@ -85,19 +120,28 @@ func checkGroup(name string, group Group, waitGroup *sync.WaitGroup, stopChannel
 	for {
 		select {
 		case <-stopChannel:
+			if verbose > 0 {
 				log.Println("checkGroup", name, "stopChannel")
+			}
 			waitGroup.Done()
 			return
-			break
 		default:
 			for host, channel := range channels {
 				select {
 				case stop := <-stopChannel:
+					if verbose > 0 {
 						log.Println("checkGroup", name, "stopChannel", stop)
+					}
 					break
 				case status := <-channel:
+					if verbose > 1 {
+						log.Println("Status for ", host, "was", statusPerHost[host], "in group", name)
 						log.Println("Status for ", host, "is", status, "in group", name)
-            updateTables( host, status, group.Tables )
+					}
+          if statusPerHost[host] == -1 || statusPerHost[host] != status {
+            statusPerHost[host] = status
+					  updateTables(host, status, group.Tables)
+          }
 				default:
 					time.Sleep(100 * time.Millisecond)
 				}
@@ -106,7 +150,7 @@ func checkGroup(name string, group Group, waitGroup *sync.WaitGroup, stopChannel
 	}
 }
 
-func updateTables( host string, status int, tables []string ) {
+func updateTables(host string, status int, tables []string) {
 	for _, table := range tables {
 		op := "add"
 		if status != 0 {
@@ -127,7 +171,9 @@ func checkHost(status chan<- int, group string, host string, check Check, waitGr
 	for {
 		select {
 		case <-stopChannel:
+			if verbose > 0 {
 				log.Println("checkHost", host, "group", group, "stopChannel")
+			}
 			waitGroup.Done()
 			return
 		default:
@@ -145,19 +191,20 @@ func checkHost(status chan<- int, group string, host string, check Check, waitGr
 				}
 				if err != nil {
 					status <- 1
+					if verbose > 1 {
 						log.Println("checkHost", host, "group", group, "error", err)
+					}
 				} else {
 					status <- 0
 				}
 			}
-			time.Sleep(300*time.Millisecond)
+			time.Sleep(300 * time.Millisecond)
 		}
 	}
 }
 
 func CheckHTTP(host string, check Check) error {
 
-
 	client := &http.Client{
 		Timeout: time.Duration(check.Timeout) * time.Second,
 	}
@@ -179,7 +226,7 @@ func CheckHTTP(host string, check Check) error {
 }
 
 func CheckTCP(host string, check Check) error {
-  cnx, err := net.DialTimeout("tcp", fmt.Sprintf("%s:%d", host, check.Port), time.Duration(check.Timeout) * time.Second)
+	cnx, err := net.DialTimeout("tcp", fmt.Sprintf("%s:%d", host, check.Port), time.Duration(check.Timeout)*time.Second)
 	if err != nil {
 		return err
 	}
@@ -193,11 +240,15 @@ func CheckSMTP(host string, check Check) error {
 
 func validateConfiguration(conf map[string]Group) error {
 	for name, group := range conf {
+		if verbose > 1 {
 			log.Println("Validating configuration", name)
+		}
 		if len(group.Tables) == 0 {
 			return errors.New(fmt.Sprintf("No tables in group %s", name))
 		}
+		if verbose > 1 {
 			log.Println("Hosts", group.Hosts)
+		}
 		if len(group.Hosts) == 0 {
 			return errors.New(fmt.Sprintf("No hosts in group %s", name))
 		}
@@ -234,7 +285,7 @@ func validateConfiguration(conf map[string]Group) error {
 			}
 
 		default:
-      return errors.New(fmt.Sprintf("Check type should be http, smtp or tcp in group %s",name))
+			return errors.New(fmt.Sprintf("Check type should be http, smtp or tcp in group %s", name))
 		}
 		if group.Check.Interval == 0 {
 			group.Check.Interval = 5

hostchecker.rc

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+. /etc/rc.subr
+
+name=hostchecker
+rcvar=hostchecker_enable
+
+command="/usr/local/bin/${name}" 
+command_args="&"
+
+load_rc_config $name
+run_rc_command "$1"