first version

is_master.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+  "fmt"
+  "flag"
+  "os"
+  "syscall"
+  "strings"
+  "net"
+  "regexp"
+)
+
+// Option to parse
+var (
+  HELP    = flag.Bool("help", false, "print the help message")
+  IP      = flag.String("ip", "", "")
+  FILE    = flag.String("file", "", "")
+  COMMAND = flag.String("command", "", "command to execute")
+)
+
+// Critical print a message and exit with code 2
+func Critical(msg string) {
+  fmt.Println(fmt.Sprintf("CRITICAL - %s", msg))
+  os.Exit(2)
+}
+
+// Warning print a message and exit with code 1
+func Warning(msg string) {
+  fmt.Println(fmt.Sprintf("WARNING - %s", msg))
+  os.Exit(1)
+}
+
+// Ok print a message and exit with code 0
+func Ok(msg string) {
+  fmt.Println(fmt.Sprintf("OK - %s", msg))
+  os.Exit(0)
+}
+
+func init() {
+  flag.Parse()
+
+  if *HELP {
+    flag.PrintDefaults()
+    os.Exit(3)
+  }
+
+  if *IP == "" && *FILE == "" {
+    Critical("Please set file or ip option")
+  }
+
+  if *COMMAND == "" {
+    Critical("Please set command option")
+  }
+}
+
+// fileExist return true if the file exist
+func fileExist(path string) bool {
+    _, err := os.Stat(*FILE)
+    if err == nil {
+      return true
+    }
+
+    return false
+}
+
+// ipExist return true if an interface has the ip 
+func ipExist(ip string) bool {
+  r := regexp.MustCompile(`^(.*)/\d{1,2}$`)
+
+  ifaces, _ := net.Interfaces()
+  for _, i := range ifaces {
+      addrs, _ := i.Addrs()
+      for _, addr := range addrs {
+        match := r.FindSubmatch([]byte(fmt.Sprintf("%s", addr)))
+        if len(match) == 0 {
+          continue
+        }
+
+        if string(match[1]) == ip {
+          return true
+        }
+      }
+  }
+
+  return false
+}
+
+func main() {
+  var isMaster bool
+
+  if *FILE != "" {
+    isMaster = fileExist(*FILE)
+  } else {
+    isMaster = ipExist(*IP)
+  }
+
+  if isMaster == false {
+    Ok("OK - I am slave, i going to sleep")
+  }
+
+  command := strings.Split(*COMMAND, " ")
+  syscall.Exec(command[0], command, []string{})
+}