func main()

in docker/peer-finder/templates/peer-finder.go [72:154]
70 lines of code
19 McCabe index (conditional complexity)

func main() {
	flag.Parse()

	ns := *namespace
	if ns == "" {
		ns = os.Getenv("POD_NAMESPACE")
	}
	hostname, err := os.Hostname()
	if err != nil {
		log.Fatalf("Failed to get hostname: %s", err)
	}
	var domainName string

	// If domain is not provided, try to get it from resolv.conf
	if *domain == "" {
		resolvConfBytes, err := ioutil.ReadFile("/etc/resolv.conf")
		resolvConf := string(resolvConfBytes)
		if err != nil {
			log.Fatal("Unable to read /etc/resolv.conf")
		}

		var re *regexp.Regexp
		if ns == "" {
			// Looking for a domain that looks like with *.svc.**
			re, err = regexp.Compile(`\A(.*\n)*search\s{1,}(.*\s{1,})*(?P<goal>[a-zA-Z0-9-]{1,63}.svc.([a-zA-Z0-9-]{1,63}\.)*[a-zA-Z0-9]{2,63})`)
		} else {
			// Looking for a domain that looks like svc.**
			re, err = regexp.Compile(`\A(.*\n)*search\s{1,}(.*\s{1,})*(?P<goal>svc.([a-zA-Z0-9-]{1,63}\.)*[a-zA-Z0-9]{2,63})`)
		}
		if err != nil {
			log.Fatalf("Failed to create regular expression: %v", err)
		}

		groupNames := re.SubexpNames()
		result := re.FindStringSubmatch(resolvConf)
		for k, v := range result {
			if groupNames[k] == "goal" {
				if ns == "" {
					// Domain is complete if ns is empty
					domainName = v
				} else {
					// Need to convert svc.** into ns.svc.**
					domainName = ns + "." + v
				}
				break
			}
		}
		log.Printf("Determined Domain to be %s", domainName)

	} else {
		domainName = strings.Join([]string{ns, "svc", *domain}, ".")
	}

	if *svc == "" || domainName == "" || (*onChange == "" && *onStart == "") {
		log.Fatalf("Incomplete args, require -on-change and/or -on-start, -service and -ns or an env var for POD_NAMESPACE.")
	}

	myName := strings.Join([]string{hostname, *svc, domainName}, ".")
	script := *onStart
	if script == "" {
		script = *onChange
		log.Printf("No on-start supplied, on-change %v will be applied on start.", script)
	}
	for newPeers, peers := sets.NewString(), sets.NewString(); script != ""; time.Sleep(pollPeriod) {
		newPeers, err = lookup(*svc)
		if err != nil {
			log.Printf("%v", err)
			continue
		}
		if newPeers.Equal(peers) || !newPeers.Has(myName) {
			log.Printf("Have not found myself in list yet.\nMy Hostname: %s\nHosts in list: %s", myName, strings.Join(newPeers.List(), ", "))
			continue
		}
		peerList := newPeers.List()
		sort.Strings(peerList)
		log.Printf("Peer list updated\nwas %v\nnow %v", peers.List(), newPeers.List())
		shellOut(strings.Join(peerList, "\n"), script)
		peers = newPeers
		script = *onChange
	}
	// TODO: Exit if there's no on-change?
	log.Printf("Peer finder exiting")
}