func()

in cmd/node-cache/app/configmap.go [84:130]

• 37 lines of code
• 6 McCabe index (conditional complexity)

func (c *CacheApp) updateCorefile(dnsConfig *config.Config) {
	// construct part of the Corefile
	baseConfig, err := ioutil.ReadFile(c.params.BaseCoreFile)
	if err != nil {
		clog.Errorf("Failed to read node-cache coreFile %s - %v", c.params.BaseCoreFile, err)
		setupErrCount.WithLabelValues("configmap").Inc()
		return
	}
	stubDomainStr := getStubDomainStr(dnsConfig.StubDomains, &stubDomainInfo{Port: c.params.LocalPort, CacheTTL: defaultTTL,
		LocalIP: strings.Replace(c.params.LocalIPStr, ",", " ", -1)})
	upstreamServers := strings.Join(dnsConfig.UpstreamNameservers, " ")
	if upstreamServers == "" {
		// forward plugin supports both nameservers as well as resolv.conf
		// use resolv.conf by default and use TCP for upstream.
		upstreamServers = "/etc/resolv.conf"
		baseConfig = bytes.Replace(baseConfig, []byte(UpstreamServerVar), []byte(upstreamServers), -1)
	} else {
		// Use UDP to connect to custom upstream DNS servers.
		upstreamUDP := bytes.Replace([]byte(upstreamUDPBlock), []byte(UpstreamServerVar), []byte(upstreamServers), -1)
		// In case upstream was configured for TCP in the existing config, change to UDP since we now have custom upstream
		baseConfig = bytes.Replace(baseConfig, []byte(upstreamTCPBlock), upstreamUDP, -1)
		// Just in case previous replace failed due to different indentation in config file or existing config was
		// already using UDP, this step will put in the correct upstream servers.
		if bytes.Contains(baseConfig, []byte(UpstreamServerVar)) {
			clog.Warningf("Did not find TCP upstream block to replace, assuming upstreams already use UDP.")
			baseConfig = bytes.Replace(baseConfig, []byte(UpstreamServerVar), []byte(upstreamServers), -1)
		}
	}
	baseConfig = bytes.Replace(baseConfig, []byte(UpstreamClusterDNSVar), []byte(c.clusterDNSIP.String()), -1)
	baseConfig = bytes.Replace(baseConfig, []byte(LocalListenIPsVar), []byte(strings.Replace(c.params.LocalIPStr, ",", " ", -1)), -1)
	// All Listen IP Substitutions should have happened with replacing "LocalListenIPsVar". This is to ensure that no
	// variables are left unsubstituted.
	if bytes.Contains(baseConfig, []byte(LocalDNSServerVar)) {
		baseConfig = bytes.Replace(baseConfig, []byte(LocalDNSServerVar), []byte(""), -1)
	}

	newConfig := bytes.Buffer{}
	newConfig.WriteString(string(baseConfig))
	newConfig.WriteString(stubDomainStr)
	if err := ioutil.WriteFile(c.params.CoreFile, newConfig.Bytes(), 0666); err != nil {
		clog.Errorf("Failed to write config file %s - err %v", c.params.CoreFile, err)
		setupErrCount.WithLabelValues("configmap").Inc()
		return
	}
	clog.Infof("Updated Corefile with %d custom stubdomains and upstream servers %s", len(dnsConfig.StubDomains), upstreamServers)
	clog.Infof("Using config file:\n%s", newConfig.String())
}